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I C A O 9357 PART*3

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4843416 0039364 477 m

9157-ARf901 Part 3 Amendment Bo 2 31/8/89 DOC

.

AMENDMENT NO. 2 TO TBE

AERODROME DESIGN MANUAL PART 3

PAVEMENTS SECOND EDITION

- 1983

1.

Amendmen€ No, 2 includes guidance material on grooving runway i n t e r s e c t i o n s and t h ec o n s t r u c t i mo fa s p h a l t i co v e r l a y s .A l s oi n c l u d e d are updated data. an ACRs f o r a i r c r a f t .

2.

Replaceexistingpages Cvii), 3--219 t o 3-224, 3-346 by t h e a t t a c h e d new pages.

3.

Remove exiatfng pages 3-347 and 3-348.

5.

Recora the entry

3-237 t o 3-249 and 3-339 t o

o f t h i s amendment on page ( i i ) .

DOC 9157-Ah/901 Part 3 1 Amendment No. 25/10/85

Transmittal Note

AMENDMENT No. 1 TO THE AERODROME DESIGN MANUAL PART 3

PAVEMENTS Second E d i t i o n

-

1983

1. The purpose o f t h i s amendment i s to update the computer programmes, f o rt h e of s e v e r a l new a i r c r a f t t y p e s . d e t e r m i n a t i o n of ACNs and t o i n c o r p o r a t e d a t a i n r e s p e c t 2.

P l e a s ree p l a c teh e x i s t i n g pages

3.

Remove p a g e3s- 2 9 1 t o

4.

Record e n t r y o f Amendment No. 1, dated 25/10/85,

by t haet t a c h e cdo r r e s p o n d i n g

3-298 which have been

new pages.

d e l e t e d by t h i s amendment. on page ( i i ) .

I C A O 9357 P A R T S 3

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W 4 8 4 3 4 3 6 0039366 2LJT

DOC9157-AN/901

AERODROME DESIGN MANUAL

PART 3 PAVEMENTS SECOND EDITION - 1983

Approved by the Secretav General and published under his authority

IkTERhATIOhAL CIVIL AVIATION ORGAhIZATlObi

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Published in separate English, French, Russian and Spanish editions by the lnternational Civil Aviation Organization. All correspondence, except orders and subscriptions, should be addressed to the Secretary General. Orders for this publication should be sent to one of the following addresses, together with the appropriateremittance (by bank draftor post office money order) in U.S. dollars or the currency of the country in which the order is placed. Document Sales Unit International Civil Aviation Organization 1000 Sherbrooke Street West, Suite 400 Montreal, Quebec Canada H3A 2R2 Argentina. El Ateneo, Pedro Garcia S.A.L.E. e I., Dpto. Compras - Irnportacibn, Patagones 2463, 1282 Buenos Aires. Egypt. ICAO Representative, Middle East and Eastern African Office, 16 Hassan Sabri, Zamalek, Cairo. France. Representant de I’OACI, Bureau Europe, 36is, villa Emile-Bergerat, 92522 Neuilly-sur-Seine, Cedex. India. Oxford Book and Stationery Co., Scindia House, New Delhi or 17 Park Street, Calcutta. Japan. Japan Civil Aviation Promotion Foundation, 15- 12, 1-chome, Toranomon, Minato-Ku, Tokyo. Mexico. Representante de la OACI, Oficina Norteamerica y Caribe, Apartado postal 5-377, Mexico 5, D.F. Peru. Representante de la OACI, Oficina Sudamerica, Apartado 4127, Lima 100. Senegal. Representant de I’OACI, Bureau Afrique, Boite postale 2356, Dakar. Spain. Libreria de Aeroniutica y Astroniutica Sumaas, Desengaiio, 12-3’-3, Madrid 13. Thailand. ICAO Representative, Asia and Pacific Office, P.O. Box 614, Bangkok. United Kingdom. Civil Aviation Authority, Printing and Publications Services, Greville House, 37 Gratton Road, Cheltenham, Glos., GL50 2BN.

Do you receive the ICAO BULLETIN? The ICAO Bulletin containsaconcise account of the activities of the Organization as well as articles of interest to the aeronautical world. The Bulletin willalso keep you up to date on the latest ICAO publications, their contents, amendments, supplements, corrigenda, and prices.

_ .

.

.

. ..

.-Aviilabreinthree separate editions: English, French and Spanish. Annual subscription: US. $1 5.00 (surface mail); US. $20.00 (air mail).

I C A O 9357 P A R T * 3

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e Aerodrome Design Manual (DOC9157-AN/901)

Part 3

Pavements Second Edition - 1983

AMENDMENTS The issue of amendments is announced in the ICAO Bulktin a n 1d in the monthly supplements to the Catabgue of IC40 I44blimtkms, which holden of this publication should consult. These amendments are available free upon request.

(ii)

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FOREWORD

This revised and updated version of t h e Aerodrome Design ManuaZ, P a r t 3, i n c l u d e s g u i d a n c e on t h e d e s i g n of p a v e m e n t s i n c l u d i n g t h e i r c h a r a c t e r i s t i c s a n d on e v a l u a t i o n a n d r e p o r t i n g of t h e i r b e a r i n g s t r e n g t h . The material i n c l u d e d h e r e i n i s closely associated with the specifications contained in Annex 14 Aerodromes. Themain p u r p o s e o f t h i s Manual i s t o e n c o u r a g e t h e u n i f o r m a p p l i c a t i o n o f t h o s e s p e c i f i c a t i o n s and t o p r o v i d e i n f o r m t i o n a n d g u i d a n c e t o S t a t e s . The s i g n i f i c a n t a d d i t i o n s / r e v i s i o n s t o the Manual as a r e s u l t of t h i s r e v i s i o n are:

-

a)

background information on t h e ACN-PCN method f o r r e p o r t i n g pavement bearingstrength(Chapter 1);

. *

b)

material o nr e g u l a t i n go v e r l o a do p e r a t i o n s( C h a p t e r

c)

updated material on evaluatfonofpavements(Chapter surface texture and drainage characteristics (Chapter

2);

3 ) and on runway 5);

d)updated material o n t h e d e s i g n - a n d e v a l u a t i o n o f p a v e m e n t s p r o v i d e d Canada, F r a n c e , t h e U n i t e d Kingdom a n d s t h e U n i t e d S t a t e s ( C h a p t e r

by

4);

e)

g u i d a n c eo np r o t e c t i o no fa s p h a l tp a v e m e n t s( C h a p t e r

f)

material o n s t r u c t u r a l d e s i g n c o n s i d e r a t i o n s f o r c u l v e r t s a n d b r i d g e s (Chapter 7).

6 ) ; and

Chapter 4 o f t h i s Manual i s based on updated material on pavement d e s i g n a a n d e v a l u a t i o n s u b m i t t e d by S t a t e s a n d i s , t h e r e f o r e , b e l i e v e d t o b e c u r r e n t . S h o u l d S t a t e , a t any time, c o n s i d e r t h a t t h e material i n c l u d e d t h e r e i n i s o u t o f d a t e , it should inform the Secretary General o f t h i s and, i f p o s s i b l e , p r o v i d e a p p r o p r i a t e r e v i s e d material.

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TABLE OF CONTENTS

Page

......................................................................... (ix) ................ 3-1 Chapter 1.- Procedures for Reporting Aerodrome Pavement Strength ... 3-1 1.1 Procedure for pavements meant for heavy aircraft (ACN/PCN method) 1.2 Procedure for pavements meant for light aircraft.................... 3-16 3-17 Chapter 2.- Guidance on Overload Operations ..................................... 3-17 2.1 Criteria suggested in Annex 14. Attachment B ........................ 2.2 State practices ..................................................... 3-17 2.2.1 Canadian practice .......................................... 3-17 3-18 2.2.2 French practice ............................................ 2.2.3 United Kingdom practice ...................................... 3-20 Chapter 3.- Evaluation of Pavements ............................................. 3-22

Glossary

............................................................. 3.2 Elements of pavement evaluation ..................................... 3.3 Elements of the ACN/PCN method ...................................... 3.4 Assessing the magnitude and composition of traffic .................. ........................... 3.5 Techniques for "using aircraft" evaluation 3.6 Techniques and equipment for "technical" evaluation................. Chapter 4.- State Practices for Design and Evaluation of Pavements .............. 4.1 Canadian practice ................................................... 4.1.1 Scope ....................................................... 4.1.2 Pavement design practices ................................... 3.1 General

............................... 4.2 French practice ..................................................... ..................................................... 4.2.1General 4.2.2 Choice of the design load ................................... 4.2.3 Designing flexible pavements ................................ 4.2.4 Designing rigid pavements ................................... 4.2.5Generaldesign .............................................. 4.1.3 Pavement evaluation practices

3-22 3-22 3-23 3-25 3-27 3-31 3-62 3-62 3-62 3-64 3-69 3-78 3-78 3-80 3-83 3-86 3-93

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Chapter 4 ( C m t

. ........................................... ...................................................... ............................................ .................................... .................................

4.2.6 Optimized design 4.2.7Frost 4.2.8Allowableloads 4.2.9 Evaluation of pavements 4.2.10 Reinforcement of pavements 4.2.11 Light pavements

............................................

............................................ 4.3.1 Design and evaluation of pavements ......................... 4.3.2 Reporting pavement strength ................................ United States of America practice.................................. 4.4.1 Introduction ............................................... 4.4.2 Basic investigations and considerations .................... 4.4.3 Soil tests ................................................. 4.4.4 Unified soil classification system ......................... 4.4.5 Soil classification examples ............................... 4.4.6 Frost and permafrost....................................... 4.4.7 Soil strength tests ........................................ 4.4.8 Pavement design philosophy ................................. 4.4.9 Background ................................................. 4.4.10 Aircraft considerations .................................... 4.4.11 Determination of design aircraft........................... 4.4.12 Determination of equivalent annual departures by the design aircraft.......................................... 4.4.13 Designing the flexible pavement ............................ 4.4.14 Critical and non-critical areas ............................ 4.4.15 Stabilized base and sub-base ............................... 4.4.16 Stabilized sub-base and base equivalency factors ........... 4.4.17 Design example............................................. 4.4.18 Designing the rigid pavement ............................... 4.4.19 Sub-base requirements...................................... 4.4.20 Critical and non-critical areas ............................ 4.4.21 Stabilized sub-base ........................................ 4.4.22 Design example............................................. 4.4.23 Optional rigid pavement design curves ...................... 4.4.24 High traffic volumes ....................................... 4.4.25 Reinforced concrete pavement............................... 4.4.26 Airport pavement overlays ..................................

4.3 United Kingdom practice

4.4

........................................

4.4.27 Pavement: evaluation

....................... 5.1 Purpose ............................................................ 5.2 Basic Considerations ............................................... 5.3 Surface treatment of runways .......................................

Chapter 5.- Methods for Improving Runway Surface Texture

3-109 3-112 3-114 3-120 3-12;

3-127 3-129 3-129 3-129 3-130 3-130 3-130 3-131 3-133 3-137 3-140 3-141 3-143 3-145 3-146 3-147 3-147 3-149 3-160 3-160 3-160 3-161 3-163 3-164 3-174 3-174 3-175 3-175 3-183 3-183 3-185 3-199 3-204 3-204

3-204 3-212

I C A O 9157 P A R T 8 3

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Pavements

Page .

...................................... ..............................................................

Chapter 6.- Protection of Asphalt Pavements 6.1

The problem

3-225 3-225

................................................. 3-226 6.3 Protective coatings ......................................................3-226 6.4 Materials for protective coatings........................................ 3-227 Application ..............................................................3-228 6.5 6.6 Protection gained ..........................................................3-228 Maintenance consideration ................................................ 3-229 6.7 Some related concerns .................................................... 3-229 6.8 Chapter 7.- Structural Concernsfor Culverts and Bridges......................... 3-230 7.1 Problem description ...................................................... 3-230 Types of substructures ................................................... 3-230 7.2 7.3. Some guiding concepts.................................................... 3-231 7.4 Evaluation of subsurface structures ...................................... 3-231 7.5 Considerations in designof new facilities ............................... 3-234 6.2

Treatment of the problem

C h a p t e r 8.-

...................................

Construction of Asphaltic Overlays

............................................................

8.1

Introduction

8.2

Airport authority's role

8.3

Design considerations

. Appendix 2 .

Appendix 1

. Appendix 4 . Appendix 3

Aircraft

................................................... Characteristics Affecting Pavement Bearing Strength .......

Procedures for an Aircraft Pavement

................................................

Determining

the

Aircraft

Classification

Number

........................................................ Design and Evaluation Graphs Provided by France ...........

Background Informationon the United States the Design and-Evaluation of Pavements

Practice

3-237 3-237 3-238B 3-239

of 3-251 3-299

for

.............................

....................................

Appendix 5 . ACNs for Several Aircraft Types

3-237

3-311 3-339

31/8/89 No

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I C A O 9357 P A R T f 3

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GLOSSARY

Terms which are d e f i n e d i n t h e ICAO Lexicon Volume I1 (Doc 9110) are used i n a c c o r d a n c ew i t ht h em e a n i n g sa n du s a g e sg i v e nt h e r e i n . A w i d ev a r i e t yo f terms is i n usethroughouttheworldtodescribesoils,construction materials, andcomponents of a i r p o r tp a v e m e n t s . A s f a r as p o s s i b l e t h e terms used i n t h i s document are t h o s e which h a v et h ew i d e s ti n t e r n a t i o n a lu s e . However, f o rt h ec o n v e n i e n c e of t h er e a d e r a s h o r t l i s t of p r e f e r r e d terms andsecondary terms which are c o n s i d e r e d t o b e t h e i r e q u i v a l e n t , and t h e i r d e f i n i t i o n s , i s givenbelow. P r e f e r r e d Term

Secondary Term

Definition

Aggregate

General term f o r t h e m i n e r a l f r a g m e n t s o r p a r t i c l e s which, through the agency of a s u i t a b l e b i n d e r , c a n b e combined i n t o a s o l i d mass, e . g . , t o form a pavement.

AircraftClassificat i o n Number (ACN)

A number e x p r e s s i n g t h e r e l a t i v e e f f e c t of a n a i r c r a f t on a pavement f o r a specified standard subgrade strength.

Asphalc t iocn c r e t e

Bitumen c o n c r e t e

A graded mixture of aggregate, and f i l l e r w i t h a s p h a l t o r bitumen, placed hot or cold, and rolled.

Base course

Base

The l a y e r o r l a y e r s of s p e c i f i e d o r s e l e c t e d material of designed thickness placed on a s u b - b a s e o r s u b g r a d e t o support a surface course.

Bearing strength

Bearing capacity Pavement s t r e n g t h

The m e a s u r e o f t h e a b i l i t y o f a pavement t o s u s t a i n t h e a p p l i e d l o a d .

CBR

California Bearing Ratio

The b e a r i n g r a t i o of s o i l determined by conparing the penetration load of the s o i l t o t h a t of a s t a n d a r d material (see ASTM D1883). Themethod covers evaluation of the relative quality of subgrade soils but i s a p p l i c a b l e t o sub-baseand some base course materials.

Compos it e pavement

A pavement c o n s i s t i n g of b o t h f l e x i b l e and rigid layers with or without separating granular layers.

ICAO 9357 PART*3

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Aerodrome Design Manual

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P r e f e r r e d Term

W 4 8 l l 5 4 3 6 0059375 252 W

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Secondary Term

Definition

F l e x i b l e pavement

A pavement s t r u c t u r e t h a t m a i n t a i n s intimate c o n t a c t w i t h a n d d i s t r i b u t e s loads to the subgrade and depends on aggregate interlock, particle friction, and cohesion for stability.

Overlay

on e x i s t i n g pavement e i t h e r w i t h o r w i t h o u t i n t e r m e d i a t e base o r s u b - b a e e coursesl usually to strengthen the pavement o r r e s t o r e t h e p r o f i l e o f t h e surface.

Pavement Classif icat i o n Number (PCN)

A number e x p r e s s i n g t h e b e a r i n g

An a d d i t i o n a l s u r f a c e c o u r s e p l a c e d

s t r e n g t h o f a pavement f o r u n r e s t r i c t e d operatione.

Pavement s t r u c t u r e

Pavement

The combination of sub-baae, baee course, and surface c~llrseplaced on a subgrade to support the traffic load a n d d i s t r i b u t e i t t o t h e subgrade.

Portland cement concrete

Concrete

A d x t u r e of graded aggregate with

Portland cement and water. A pavement s t r u c t u r e t h a t d i e t r i b u t e e l o a d s t o t h e s u b g r a d e h a v i n g as i t s surface course a Portland cement

Rigid pavement

concrete slab of relatlvely high bending resistance. Sub-baae course

Sub+e

e

The l a y e r o r l a y e r s o f s p e c i f i e d

s e l e c t e d material of designed thickness placed on a s u b g r a d e t o s u p p o r t a base courae. Subgrade

Formation foundation

The u p p e r p a r t of t h e s o i l , n a t u r a l o r conetructed, which supports the loads t r a n s m f t t e d by t h e pavement.

Surf ace course

Wearing course

The t o p c o u r s e of a pavement s t r u c t u r e .

J

I C A O 9357 P A R T * 3

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4 8 4 3 4 3 b 0039376 199

CHAPTER 1.-

PROCEDURES FOR REPORTING

P r o c e d u r ef o r

pavementsmeant

1.1.1

AERODROME PAVEMENT STRENGTH

f o r heavy a i r c r a f t (ACN-PCN method)

Introduction

1.1.1.1 Annex 14, 2.5.2 s p e c i f i e st h a t h eb e a r i n gs t r e n g t h of a pavement intended f o r a i r c r a f t of mass g r e a t e r t h a n 5 700 kg s h a l l b e made a v a i l a b l e u s i n g t h e a i r c r a f t c l a s s i f i c a t i o n number - pavement c l a s s i f i c a t i o n number (ACN-PCN) method. To f a c i l i t a t e a proper understanding and usage of the ACN-PCN method t h e f o l l o w i n g material explains:

1.1.2

.

1.1 2.1

a)

t h ec o n c e p to ft h e

b)

how t h e ACNs of a n a i r c r a f t are determined.

Conceptof

method;and

t h e ACN-PCN method

Annex 1 4 d e f i n e s ACN and PCN as follows :

Am. PCN.

A number e x p r e s s i n g t h e r e l a t i v e e f f e c t of a n a i r c r a f t on a pavement f o r a specified standard subgrade strength. A number e x p r e s s i n g t h e b e a r i n g s t r e n g t h o f a pavement f o r unrestricted operations.

A t t h e o u t s e t , i t needs t o b e n o t e d t h a t t h e ACN-PCN method i s meant o n l y f o r p u b l i c a (AIPs). It t i o n of pavement s t r e n g t h d a t a in the Aeronautical Information Publications is n o t i n t e n d e d f o r d e s i g n o r e v a l u a t i o n ofpavements, nor does i t contemplate the use of a s p e c i f i c method by t h e a i r p o r t a u t h o r i t y e i t h e r f o r t h e d e s i g n o r e v a l u a t i o n of In f a c t , t h e ACN-PCN method d o e s p e r m i t S t a t e s t o u s e a n y d e s i g n / e v a l u a t i o n pavements. method of t h e i r c h o i c e . To t h i s end, t h e method s h i f t s t h e e m p h a s i s f r o m e v a l u a t i o n of pavements t o e v a l u a t i o n of l o a d r a t i n g of a i r c r a f t (ACN) and includes a s t a n d a r d procedu r e f o r e v a l u a t i o n of t h e l o a d r a t i n g o f a i r c r a f t . The s t r e n g t h o f a pavement i s r e p o r t e d u n d e r t h e method i n terms o f t h e l o a d r a t i n g o f t h e a i r c r a f t which t h e pavement can accept on an unrestricted basis. The a i r p o r t a u t h o r i t y c a n u s e a n y methodof h i s choice to determine the load rating of his pavement. If, in t h e a b s e n c e of t e c h n i c a l evaluation, he chooses to go on t h e b a s i s o f t h e u s i n g a i r c r a f t e x p e r i e n c e , t h e n h e would compute t h e ACN o f t h e most c r i t i c a l a i r c r a f t u s i n g o n e o f t h e p r o c e d u r e s d e s c r i b e d below, c o n v e r t t h i s f i g u r e i n t o a n e q u i v a l e n t PCN and publish i t in t h e A I P as the load rating of his pavement. The PCN so r e p o r t e d would i n d i c a t e t h a t a n a i r c r a f t w i t h a n ACN e q u a l t o o r less t h a n t h a t f i g u r e c a n o p e r a t e on t h e pavement s u b j e c t t o any l i m i t a t i o n on t h e t i r e pressure.

1.1.2.2 The ACN-PCN method c o n t e m p l a t e st h er e p o r t i n go f pavement s t r e n g t h s on a continuous scale. The lowerendofthe scale i s z e r o a n d t h e r e i s noupper end. Addit i o n a l l y , t h e same scale i s used t o measure t h e l o a d r a t i n g s of b o t h a i r c r a f t a n d pavements.

3-1

3-2

Aerodrome Design Manual

1.1.2.3 To f a c i l i t a t et h e u s e of t h e method, a i r c r a f m t a n u f a c t u r e r s will p u b l i s h , i n t h e m documents d e t a i l i n g t h e c h a r a c t e r i s t f c s of t h e i r a i r c r a f t , ACTS conputed a t ~ W Odifferent masses: maximum apron mass, and a representative operating massempty, both on r i g i d and f l e x i b l e pavements and for the four standard subgrade strength categories. Nevertheless, f o r t h e s a k e of convenience Annex 14,Attachment B andAppendix 5 hereto include a t a b l e mass used i n t h e showing t h e ACNs of a number of a i r c r a f t . It is t o b e n o t e d t h a t t h e ACN c a l c u l a t i o n is a "static" mass and that no allowance is made for an increase i n loading through dynamic e f f e c t s .

1.1.2.4 The ACN-PCN method alsoenvisagesthereporting i n respect: of each pavement: a)

pavement type;

b)

subgradecategory;

c)

-ximum

d)

pavement evaluation method used.

of thefollowinginformation

t i r e pressure allowable; and

The above d a t a are primarily intended t o e n a b l e a i r c r a f t o p e r a t o r s t o d e t e r n d a e t h e permissible aircraft types and operating masses, a n d t h e aircraft nranufacturers t o ensure compatibility between a i r p o r t pavementsand a i r c r a f t u n d e r development.There i s , hawever, no need t o r e p o r t t h e actual subgrade s t r e n g t h o r t h e maxipaurn t i r e pressure allowable.Consequently, the subgrade strengths and t i r e preseures normally encountered have beengrouped i n t o c a t e g o r i e s a8 i n d i c a t e d i n 1.1.3.2 belcw. It would b e s u f f i c i e n t i f the airport authority identifies the categories appropriate t o h i s pavement. (See a l s o t h e examples included under Annex 14, 2.5.6. )

1.1.3

How ACNE are determined

1.1.3.1 The flowchart, below, b r i e f l ye x p l a i n s computed u n d e r t h e A W P C N method.

how t h e ACNs of a i r c r a f t are

ACN COMPUTER PROGRAMME

*

,

’

RIGID + DERIVED

I

I

RIGID SINGLE NOMOGRAPH$ PAVEMENT

I

mI ,

RIGID PAVEMENT

RIGID

WHEEL CHART

Y

A TABLE SHOWING ACNs OF AIRCRAFT

I

I

I

ACN COMPUTER PROGRAMME

*

d

I

FLEXIBLE PAVEMENT

-*

v

FLEXIBLE CORPS OF ENGINEERS’ DERIVED PAVEMENT *SINGLE WHEEL NOMOGRAPHS CHART

I t A TABLE SHOWING

Y

k ~ 1

i

3

ACNs ,OFAIRCRAFT

1

, I

FLEXIBLE’

I

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3-4

1.1.3.2

Standardvaluesused a)

in t h e method and d e s c r i p t i o no ft h ev a r i o u s

terms

Subgradecategory.Inthe ACN-PCN method e i g h ts t a n d a r ds u b g r a d e values (i.e., f o u r r i g i d p a v e m n t k v a l u e s a n d f o u r f l e x i b l e pavement CBR v a l u e s ) are u s e d , r a t h e r t h a n a continuous scale of subgrade s t r e n g t h s . The grouping of subgrades with a s t a n d a r d v a l u e a t t h e m i d r a n g e of each group i s c o n s i d e r e d t o b e e n t i r e l y a d e q u a t e f o r reporting. The s u b g r a d e s t r e n g t h categories are i d e n t i f i e d as high, medium, low a n d u l t r a low a n d a s s i g n e d t h e following numerical values: Subgrade strength category High s t r e n g t h ; C h a r a c t e r i z e d by k* = 150 MN/m3 and representing valuesabove 120 ~ / I Ef? o r r i g i d pavements,and by CBB 15and r e p r e s e n t i n g a l l CBR values above 13 f o r f l e x i b l e pavements.

all k

Medium s t r e n g t h ; c h a r a c t e r i z e d by k = 80 HH/m3 and representing a range i n k of 60 t o 120 M Nd / f o r r i g i d pavements,and by CBB 10 and r e p r e s e n t i n g a range i n CBR of 8 t o 13 € o r f l e x i b l e pavements.

Low s t r e n g t h ; c h a r a c t e r i z e d by k = 40 MWm3 and representing a range i n k of 25 t o 60 HN/d f o r r i g i d pavements,and by CBB 6 and r e p r e s e n t i n g a range i n CBB of 4 t o 8 f o r f l e x i b l e pavements.

Ultra l o w s t r e n g t h ;c h a r a c t e r i z e d by k 20 MN/rn3 andrepresenting k values below25 M N d / f o r r i g i d pavemente,and by CBR = 3 and r e p r e s e n t i n g a l l CBB v a l u e s b e l o w 4 € o r f l e x i b l e pavements.

all

b )C o n c r e t ew o r k i n ge t r e s 8f o rr i g i d pavements.For r i g i d pavements, a s t a n d a r d s t r e s s f o r r e p o r t i n g p u r p o s e s is s t i p u l a t e d (a = 2.75 MPa) only as a means of eneuringuniformreporting. The working stress t o be used for the design and/or evaluation of pavements h a s no r e l a t i o n s h i p t o t h e s t a n d a r d stress f o r r e p o r t i n g . c)

Tire pressure. The r e e v l t a of pavement r e s e a r c ha n dr e - e v a l u a t i o no f o l d t e s t r e s u l t s r e a f f i r m t h a t e x c e p t f o r u n u s u a l pavement construct i o n (i.e., f l e x i b l e pavements with a t h i n a e p h a l t i c c o n c r e t e c o v e r o r weak u p p e r l a y e r s ) , t i r e p r e e s u r e effects are secondary t o load and may t h e r e f o r e b e c a t e g o r i z e d i n f o u r g r o u p s f o r wheel spacing, and r e p o r t i n gp u r p o s e s as: high, medium, low andvery o lw andassigned thefollowingnumericalvalues:

- No p r e s s u r e lidt Medium - P r e s s u r e l i m i t e d t o 1.50 MPa Low - P r e s s u r e l i m i t e d t o 1.00 MPa Very low - P r e s s u r e l i m L t e d t o 0.50 MPa High

*

Values determined using

a 75 cm d i a m e t e r p l a t e .

nf or tmt i on Hand1 i ng Servi ces, 2000

P a r t 3 . - Pavements

3-5

d )M a t h e m a t i c a l l yd e r i v e ds i n g l ew h e e ll o a d : The concept of a mathematically derived single wheel load has been employed i n t h e ACN-PCN method as a means t o d e f i n e t h e l a n d i n g g e a r / p a v e m e n t i n t e r actionwithoutspecifying pavement t h i c k n e s s as a n ACN parameter. T h i s i s done by e q u a t i n g t h e t h i c k n e s s g i v e n by t h e m a t h e m a t i c a l model for an aircraft landing gear t o t h e t h i c k n e s s f o r a single wheel a t a s t a n d a r d t i r e p r e s s u r e o f 1.25 MPa. The s i n g l e w h e e l l o a d so obtained i s thenusedwithoutfurtherreferencetothickness;this i s so b e c a u s e t h e e s s e n t i a l s i g n i f i c a n c e i s a t t a c h e d t o t h e f a c t of having equalthicknesses,implying "same a p p l i e d stress t o t h e pavement", r a t h e rt h a nt h em a g n i t u d e of t h e t h i c k n e s s . The f o r e g o i n g i s i n ACN-PCN method t o e v a l u a t e t h e accord with the objective of the relative loading effect of an aircraft on a pavement. e)

A i r c r a f t c l a s s i f i c a t i o n number (ACN). "he ACN of a n a i r c r a f t i s n u m e r i c a l l yd e f i n e d as two times t h ed e r i v e ds i n g l ew h e e ll o a d ,w h e r e the derived single wheel load i s e x p r e s s e d i n thousands of kilograms. A s noted previously, the single wheel tire pressure i s standardized a t 1.25 MPa. Additionally,thederivedsinglewheelload i s a function ofthesubgradestrength. The a i r c r a f t c l a s s i f i c a t i o n number (ACN) is defined only for the four subgrade categories (i.e., h i g h , medium, low, a n d u l t r a o lw s t r e n g t h ) . The"two" (2) f a c t o r i n t h e n u m e r i c a l d e f i n i t i o n o f t h e ACN i s used' t o achieve. a s u i t a b l e ACN v s . g r o s s mass scale so t h a t w h o l e number ACNs may b e u s e d w i t h r e a s o n a b l e a c c u r a c y . Because a n a i r c r a f t o p e r a t e s a t v a r i o u s mass a n d c e n t r e of g r a v i t y conditions the following conventions have been used in ACN computat i o n s (see F i g u r e 1-1).

1.1.3.3

1)

t h e maximum ACN of a n a i r c r a f t i s c a l c u l a t e d a t t h e mass and c.g. that produces the highest main g e a r l o a d i n g o n t h e pavement, The u s u a l l y t h e maximum ramp mass a n d c o r r e s p o n d i n g a f t c . g . a i r c r a f t tires are c o n s i d e r e d as i n f l a t e d t o t h e m a n u f a c t u r e r s recommendation f o r t h e c o n d i t i o n ;

2)

relative a i r c r a f t ACN c h a r t s a n d t a b l e s show t h e ACN as a f u n c t i o n of a i r c r a f t g r o s s mass w i t h t h e a i r c r a f t c.g. a t a c o n s t a n t v a l u e c o r r e s p o n d i n g t o t h e maximum ACN v a l u e (i.e., u s u a l l y , t h e a f t c . g . f o r max ramp mass) and a t t h e max ramp mass t i r e p r e s s u r e ; and

3)

s p e c i f i c c o n d i t i o n ACN v a l u e s are t h o s e ACN v a l u e s t h a t are adjusted for the effects of tire pressureand/orc.g.location, a s p e c i f i e d g r o s s mass f o r t h e a i r c r a f t .

Abbreviations a)

A i r c r a fp t arameters

MRGM

- Maximum ramp g r o s s mass i n k i l o g r a m s

at

Aerodrome Design Manual

3-6

b)

Pavement and sstbgredr parePetere Q

t

- Standard working e t r e m f o r reporting,

2.75 HPa

- Pavement thickneus i n centimetres mickueso of s l a b for ri@d pavemente, or Total thickness of pav-at structural syeter burface t o subgrade) f o r f lcxible p a v e ~ e n t e(see Figure 1-21.

Figure 1-1. Landing gearloading on pavement Model DC-10 Series 30, 30CF, 40 and 40CF

a

3-7

Part 3.- Pavements

THEORETICAL ASPHALT PAVEMENT THEORETICAL

CEMENT CONCRETE PAVEMENT

7 ’ THICKNESS

1‘

Figure 1-2

k

- Westergaard’s

R

- Westergaard’s radius of relative stiffness in centimetres. This is computed usingthe following equation (see Figure 1-3). 12 (1

-

modulus of subgrade reaction in MN/m3

E is modulus of elasticity p2)k

p is Poisson’s ratio

(+

= 0.15)

PHYSICAL MEANING OF W E S T E R G A A R D S ‘RADIUS OF RELATIVE STIFFNESS’,L ON A SLAB

SINGLE WHEEL LOADING 1 I \

+

1

,pAPPROXlMATELY

CONTRAFLEXURE IN SLAB

L-----

t

I

.. --. .DEFLECTION

PLOT OF BENDING MOMENT (AND/OR TENSION STRESS O N BOTTOM OF SLAB AS A FUNCTION OF RADIAL DISTANCE FROM CENTER

L

e

W

Figure 1-3

OF LOAD)

Aerodrome Design Manual

3-8 CBR

- California Bearing Ratio

in per cent

Tire Pressures P, Pq

- Tire p r e s s u r e f o r d e r i v e d s i n g l e w h e e l l o a d - 1.25 MPa - Tire p r e s s u r e f o r a i r c r a f t a t maximre ramp mass condition

1.1.3.4 Mathematical models. Two mathematical models are used i n t h e ACN-PCN method: theWestergaardsolutionfor a loaded e l a s t i c p l a t e on a Uinklerfoundation ( i n t e r i o r l o a d case) f o r r i g i d pavements,and t h e B o u s s i n e s q s o l u t i o n f o r s t r e s s e s a n d d i s p l a c e m e n t s i n a homogeneous i s o t r o p i c e l a s t i c h a l f - s p a c e u n d e r s u r f a c e l o a d i n g f o r f l e x i b l e pavements. The useofthese two, widelyused,modelspermitsthe maximum c o r r e l a t i o n t o w o r l d w i d e pavement design methodologies, with a minimraneed f o r pavement paraueter values (i.e., onlyapproximatesubgrade k, o r CBR values are r e q u i r e d ) . 1.1.3.5 Computer programmes. The two computer programmes developed using these mathematical models are reproduced i n Appendix 2. The p r o g r a m f o r e v a l u a t t n g a i r c r a f t on r i g i d pavements i s based on t h e p r o g r a m d e v e l o p e d by Mr. R.G. Packard*of Portland Cement A s s o c i a t i o n , I l l i n o i s , USA a n d t h a t f o r e v a l u a t i n g a i r c r a f t on f l e x i b l e pavements i s based on t h e US Army Engineer Waterways Experiment S t a t i o 3 I n s t r u c t i o n R e p o r t S-77-1, e n t i t l e d" P r o c e d u r e sf o r Developmentof CBR Design Curves". It may, however, be noted that the aircraft classification tables included i n Annex 14, Attachment B and i n Appendix 5 of t h i s Manual completely eliminate the need to use these programmes i n r e s p e c t ofmost o f t h e a i r c r a f t c u r r e n t l y in use. 1.1.3.6 Graphical procedures. Aircraft for which pavement thickness requirement c h a r t s h a v e been published by t h e m a n u f a c t u r e r s c a n a l s o be evaluated using the graphic a l p r o c e d u r e s d e s c r i b e d below. 1.1.3.7 Rigid pavements. This procedure uses the conversion chart shown i n Figure 1-4 and t h e pavement thickness requirement charts published by t h e a i r c r a f t manufacturers. The Portland Cement Associationcomputer programme r e f e r r e d t o i n 1.1.3.5 was used i n developingFigure 1-4. This f i g u r e relates t h e d e r i v e d s i n g l e w h e e l load a t a constant t i r e p r e s s u r e of 1.25 MPa t o a r e f e r e n c e pavement thickness. It takes into account the four standard subgrade k v a l u e s d e t a i l e d in 1.1.3.2 a ) above,and a standard concrete stress of 2.75 HPa. The f i g u r e a l s o i n c l u d e s a n ACN scale which p e r m i t s t h e ACN t o be r e a d d i r e c t l y . The following steps are used to determine the ACN of an aircraft: a) using t h e pavement requirement chart published by themanufacturer obtain the reference thickness for the given aircraft mass, k value of the subgrade, and the standard concrete stress f o r r e p o r t i n g , i.e. 2.75 MPa; b)usingtheabovereferencethicknessandFigure single wheel load for the selected subgrade;

*

1-4,

obtain a derived

and

Refer t o document e n t i t l e d "DesignofConcreteAirport Pavement" by R.G. Portland Cement Association,Skokie,Illinois, 60076, dated 1973.

Packard,

D SW L (1 000 kg)

70 120

/

HIGH STRENGTH 150 MN/m”

/.I//

MEDIUM STRENGTH 80 MN/m3 LOW STRENGTH 40 MN/m? ULTRA-LOW STRENGTH20 MN/m3

6c) t

5c

//J

/

-

’

--

4c 3c 20

40

TIRE PRESSURE 1.25 MPa STANDARD STRESS 2.75 MPa PCA COMPUTER PROGRAMME PDILB

t

20'

10 t

0I

0

S

io

1

20

25

30

REFERENCE THICKNESS

Figure

1-4.

ACN Rigid

Pavement Conversion

Chart

35

40

45

50

55

Aerodrome Design Manual

3-10

c)

t h ea i r c r a f tc l a s s i f i c a t i o n number, a t t h es e l e c t e d mass and subgrade k v a l u e , i s two tirnes t h e d e r i v e d s i n g l e w h e e l l o a d in 1 000 kg. Note t h a t t h e ACN c a n a l s o b e read d i r e c t l y from t h e c h a r t . Note f u r t h e r t h a t t i r e p r e s s u r e c o r r e c t i o n s a r e n o t n e e d e d when t h e above procedure is used.

1.1.3.8 F l e x i b l e pavements. This procedure uses the conversion chart shown i n F i g u r e 1-5 and t h e pavement thickness requirement charts published by t h e a i r c r a f t manufacturersbased on t h e ~ i t e dStates Army Ehgineers CBR procedure. The former chart has been developed using the following expression:

Where t = r e f e r e n c e t h i c k n e s s i n cm.

DSWL = a single wheel load with

1.25 HPa t i r e p r e s s u r e

ps = 1.25 MPa

CBR = standard subgrade (Note t h a t t h e c h a r t u s e s f o u r s t a n d a r dv a l u e s 3, 6 , 10 and 15) C1

0.5695

C2 = 32.035

The r e a s o n f o r u s i n g t h e l a t t e r charts i s to obtain the equivalency between the "group of l a n d i n g g e a r w h e e l s e f f e c t " t o a d e r i v e d s i n g l e w h e e l l o a d by means of Boussinesq Deflection Factors. The f o l l o w i n g s t e p 8 are u s e d t o d e t e r m i n e t h e ACN of a n aircraft: a ) u s i n g t h e pavement requirement chart published by the manufacturer d e t e r d n e t h e r e f e r e n c e t h i c k n e s s f o r t h e g i v e n a i r c r a f t mass, subgrade category, and 10 000 coverages;

b)

e n t e r F i g u r e 1-5 w i t h t h e r e f e r e n c e t h i c k n e s s d e t e r m i n e d i n step a) and t h e CBR corresponding t o the subgrade category and read the d e r i v e d s i n g l e wheel load; and

c ) t h e ACN a t t h e s e l e c t e d me8 and subgrade category i e two times t h e d e r i v e d s i n g l e w h e e l l o a d i n 1 000 kg. Note t h a t t h e ACN c a n a l s o b e readdirectlyfromthe chart. Note f u r t h e r t h a t t i r e p r e s s u r e c o r r e c t i o n s are not needed when t h e above procedure Le used. 1.1.3-9 Tire pressure adjustment to ACN. M r c r a fnt o r m a l l y h a v teh e i r tires i n f l a t e d t o t h e p r e s s u r e c o r r e s p o n d i n g t o t h e m a x i u u m g r o s s mass a n d m a i n t a i n t h i s p r e s s u r e r e g a r d l e s s of t h e v a r i a t i o n s i n t a k e - o f f masses. There are times, however, when o p e r a t i o n s a t reduced masses and reduced t i r e p r e s s u r e s are productive and reduced ACNE need t o be calculated. To d o t h i s f o r r i g i d pavements, a chart has been prepared by t h e u s e of t h e PCA computer programme PDLLB and is given i n Figure 1-6. The example included in t h e c h a r t i t s e l f e x p l a i n s how t h e c h a r t is used.

I C A O 9357 P A R T * 3

**

m

4 8 4 3 4 3 6 0019386 038

P a r t 3 . - Pavements

m

3-11

ACN 100

90

€ul

70 60

50 40 30

20

10

REFERENCETHICKNESS CM

Figure 1-5. ACN Flexible Pavement Conversion Chart

Aerodrome Design Manual

3-12

.

1 1.3.10

For f l e x i b l e pavements, t h e CBR equation t =

LFZ

\

was used to equate thickness and solve for the reduced pressure ACN i n terms of t h e maximm t i r e p r e s s u r e ACN a t the reduced mass g i v i n g t h e f o l l o w i n g e x p r e s s i o n :

= ACN

ACN

Maximm pressure

Reduced pressure

(For values

1.1.3.11

Solution:

of C1 and C2 see 1.1.3.8.)

Worked examples

The ACN of t h e a i r c r a f t f r o m t h e t a b l e

i n Appendix 5 of t h i s Manual i s

48. It i s a l s o p o s s i b l e t o d e t e r m i n e t h e ACN of t h e a i r c r a f t u s i n g F i g u r e 1-4 a n d t h e pavement requirement chart for t h e a i r c r a f t i n F i g u r e 1-7. This method i n v o l v e s t h e f o l l o w i n g o p e r a t i o n s :

1-7 r e a d t h e t h i c k n e s s of c o n c r e t e n e e d e d f o r t h e aircraft a)fromFigure mass of 78 500 kg, the subgrade k v a l u e of 80 MN/m3, a n d t h e s t a n d a r d concrete stress of 2.75 MPa as 31.75 cm; and

b)

e n t e r F i g u r e 1-4 w i t h t h i s t h i c k n e s s a n d r e a d t h e f o r t h e medium s t r e n g t h s u b g r a d e as 2.

ACN of t h e a i r c r a f t

I C A O 9357 P A R T * 3

**

m

h 8 4 L 4 3 b 0039388 900

m

P a r t 3.- Pavements

3-13

1.2

1.1

1.o

7

CORRECTION FACTOR .9

ACN

’

ACNSTD

-

.a

An aircraft with a tire pressure of 1.25 MPa has an ACN of 50 on a medium subgrade. What would be its ACN if tire pressure is increased to 1.50 MPa?

To obtain the correction factor proceed vertically from a tire pressure of 1-50 MPa until medium subgrade curve is intercepted. Then proceed horizontally and read 1.06. ACN for TP 1.50 MPa = 1.06 x 50 = 53

Pavement thickness = 40 cm

.7

.E

.5 2.0

.751.75

1.o 1.5

1.25

2.35

TIRE PRESSURE

F i g u r e 1-6.

ACN tire p r e s s u r ea d j u s t m e n t

- r i g i dp a v e m e n t s

2.50

MPa

only

+. - _

I C A O 9L57 PART*K3

**

E 48YLYLb 0059389 847 H

3-14 Example 2:

Aerodrome Design Manual An A I P c o n t a i n st h ef o l l o w i n gi n f o r m a t i o n

related t o a runway pavement:

PCN o f t h e pavement = 80 Pavement t y prei g i d Subgrade category medium s t r e n g t h Tire p r e s s u r e l i m i t a t i o n = none Determine whether the pavement c a n a c c e p t t h e f o l l o w i n g a i r c r a f t i n d i c a t e d o p e r a t i n g m a s s e s a n d t i r e pressures:

MaSS

at at at at

Airbus A 300 Model B2

B747-100 Concorde

DC-

10-40

142 000 334 751 185066 253105

kg kg kg kg

at the

Tire p r e s s u r e

1.23 1.55 1.26 1.17

MPa MPa MPa

HPa

Solution:

ACNs o ft h e s ea i r c r a f tf r o m Appendix 5 of t h i s Manual are 44, 51, 71 and 53, r e s p e c t i v e l y . S i n c e the pavement i n q u e s t f o n h a s a PCN of 80 i t can a c c e p t a l l o f t h e s e aircraft.

Example 3:

F i n dt h e ACN of DC-10-10 a t 157 400 kg on a f l e x i b l e pavement r e s t i n g on a medium s t r e n g t h s u b g r a d e (CBR 10). The t i r e pressure of the main wheels is 1.28 MPa.

Solution:

The ACN of t h ea i r c r a f tf r o m

57

-

I57

- 157 400)x 406- 108 940)

Appendix 5 of t h i s Manual is

(196 406 (196

(57-27)

--39 006 x 30 87 466

= 57

- 13.4

= 43.6 o r

5

It i s a l s o p o s s l b l e t o d e t e r m t n e t h e ACN o f t h e a i r c r a f t u s i n g F i g u r e 1-5 a n d t h e pavement r e q u i r e n e n t c h a r t i n F i g u r e 1-8. This method i n v o l v e s the following operations:

a)

fromFigure 1-8 r e a d the t h i c k n e s s o f p a v e m e n t n e e d e d f o r t h e a i r c r a f t mass of 157 400 kg and the subgrade CBR of 10 as 57 cm; and

b)

e n t e r F i g u r e 1-5 with this t h i c k n e s s and r e a d t h e t h e s u b g r a d e CBR of 10 as

44.

ACN of a i r c r a f t €or

I C A O 7357 P A R T * 3

m

f*

H 4 B 4 1 4 L b 0037390 5 6 9

3-15

Part 3.- Pavements 124.5 x 43.2 c m TIRES - TIRE PRESSURE CONSTANT AT 11.7 kglcm’ 127 x 53.3 c m TIRES (NEW DESIGN) - TIRE PRESSURE CONSTANT AT 11.7 kg/cm*

e

NOTE: THE VALUES OBTAINED BY USING THE MAXIMUM LOAD REFERENCE LINE AND ANY VALUE OF k ARE EXACT. FOR LOADS LESS THAN MAXIMUM. THE CURVES ARE u P r a c t i c a l c a l c u l a t i o n . In t h i s way o n ec a nc a l c u l a t ef o re a c h airc r a f t c o n s i d e r e d as t h e most c r i t i c a l , t h e t h i c k n e s s r e q u i r e d by i t s maximum expected mass, t a k i n g i n t o a c c o u n t the number of a c t u a l movements a n t i c i p a t e d at t h i s mass and assuming t h a t i t would b e t h e o n l y a i r c r a f t u s i n g t h e pavementunderstudy. The maximum t h i c k n e s s t h u s obtained,plus a f e w c e n t i w s t r e s , u s u a l l y p r o d u e a s a n i n i t i a l t h i c k n e s s t h a t i s f a i r l y c l o s e t o t h e f i n a l value. The e f f e c t s of some a i r c r a f t q u i c k l y become n e g l i g i b l e as t h e t h i c k n e s s i s i n c r e a s e d i n soon as P/Po i s less t h a n 0.8). They canbe t h ei t e r a t i o n s( a s t o s i m p l i f y the c a l c u l a t l o n s . The mininmm deletedfromthetables increments i n t h e i t e r a t i o n s are g e n e r a l l y 1 cm f o r r i g i d pavements maximm and 1 t o 2 cm f o r f l e x i b l e pavements which represents the a c c u r a c y t h a t may be expected from an optimhed design.

**

I C A O 9357 P A R T * 3

m

m

46414Lb 003946b T I 9

P a r t 3 . - Pavements

1

3-111

4

3

2

6

5

7

I

I

I

Actual movements

...

...

...

r

.

.

...

To eq t auli v a l e n t

...

traffic

Equivalent movements

I

I

...

1 N'

i,

1) S u b j e c at i r c r a f t . Two models of t h e same a i r c r a f t must be considered be differentifthecharacteristicsoftheirundercarriagesdiffer (numberof w h e e l s ,s i z e ,p r e s s u r e ) . 2)

j

to

A c t u al ol a dPcs,o n s i d e r efdoera cm hodel.

3) A l l o w a b lleo a d s P a , c a l c u l a t e d by means of t h g e r a p h"s F l e x i b l p eavement" and"Rigidpavement", as a p p l i c a b l e (see Appendix 3 ) . I f t h e r e i s no g r a p hf o r the subject aircraft, one uses the graph €or the aircraft with characteristics closest t o t h e a i r c r a f t understudy.

4)

R e l a t i o n s h i p R of t h ea c t u a l o a d P t ot h ea l l o w a b l el o a d Po. T h i s r e l a t i o n s h i p must n o te x c e e d1 . 2f o ra p r o n sa n d 1.5 f o r t h e o t h e r p a v e m e n t s (it i s recommended,however, n o tt oe x c e e d1 . 2 ) .

5) W e i g h t i n gc o e f f i c i e n t a p p l y i n g the f o r m u l a :

cp

= 10

Cp c a l c u l a t e de i t h e r

7) Number N ' o ef q u i v a l e n t of t h e f o r m l a :

n o v e m e n t sp e ra i r c r a f ot v e rt h ea n t i c i p a t e d

movements t o a c t u a l movements c a l c u l a t e d by means

P I

N'= Cp x N The t o t a l e q u i v a l e n t t r a f f i c l e n t movements i n column ( 7 ) . F i g u r e 4-29.

4-30 o r by

PI

m-11

6) T o t a l number N o fa c t u a l pavement l i f e .

by means o F f igure

i s o b t a i n e d by a d d i n g t h e numberof

Computation of t o t a l e q u i v a l e n t t r a f f i c

equiva-

I C A O 9357 PART*:J

3-112

**

= 48454Lb

Aerodrome Design Manual

-

~~

0.3

00&9U0? 955

0.3

0,7 0.91

1

3

4

20

5 6 7 8 4 1 0

Weighting coefficient F i g u r e 4-30.

50

30

7 0 90100

.

200

300

of movements

Equivalentraffic

Remark

The optimized design l a t i n gt h i c k n e s s e s ,e . g . ,

4.2.7

1

- Granting of

2

- P o t e n t i a l of

method can be used for purposes other than calcu-

concessions (see 2.2.2.2

and 4 . 2 . 8 ) ;

and

remaining pavement l i f e (bycomparing t r a f f i c e q u i v a l e n t s for a n e x i s t i n g pavement).

total and past

Frost

4.2.7.1

It i s recommended t h a t s t r u c t u r e s b e t e s t e d

for t h e e f f e c t s oL f r o s t - t h a w

as follows:

a) C l a s s i f i c a t i o no f s o i l according t o f r o s t s u s c e p t i b i l i t y . The c l a s s i f i c a t i o n of t h e L a b r a t o i r e C e n t r a l d e s P o n t s~~- et: -- C - -h - -a u s s b s * (Minis te're d e s T r a n s p o r t s , France) is used t o e x p r e s s t h e f cos t s u s c e p t i b i l i t y of soils. ~

* Abbreviated

as LCPC.

I C A O 9357 P A R T * 3

**

= 484/43b

0037488 B93

P a r t 3 . - Pavements

3-113

b )D e t e r m i n a t i o no ff r o s tp e n e t r a t i o n .F r o s tp e n e t r a t i o n is determined using the modified Berggren method a d a p t e d t o t h e m u l t i - l a y e r case. The f r o s t i n d i c e s a n d thermi.c p a r a m e t e r s are d e f i n e d i n t h e same manner a s t h e LCPC.

are t h r e ef e a s i b l ep r o t e c t i o n

c )P r o t e c t i n g pavement f r o mf r o s t .T h e r e l e v e l s , as f o l l o w s :

1)

T o t a lp r o t e c t i o n .P r o t e c t i o n i s c a l c u l a t e d s o as t o e n s u r e t h a t the frost penetration determined for the exceptionally severe winter cannot reach soil layers that may b e s u s c e p t i b l e t o f r o s t . ~~~~~

2)

~

~

~~

H i g hp r o t e c t i o n . Same p r i n c i p l e as t o t a p l rotectionh ; owever, t h e f r o s t p e n e t r a t i o n i s c a l c u l a t e d f o r a not exceptionally winter

.

3)

severe

Low p r o t e c t i o n . It i s r e c o g n i z e dt h a tf r o s tu n d e rs e v e r ew i n t e r c o n d i t i o n s may p e n e t r a t e a f e w c e n t i m e t r e s i n t o t h e c o u r s e s o r intofrostsusceptiblesoil. The a c c e p t a b l e d e p t h of p e n e t r a t i o n largely depends on the individual case and w i l l b e d e t e r m i n e d i n c o n s u l t a t i o nw i t ht h eA d m i n i s t r a t i o n . The t a b l e h e r e u n d e r shows t h e recommended p r o t e c t i o n l e v e l s f o r i n f o r m a t i o n :

I

1

NATURAL SOIL

AERODROME CATEGORY

Homogeneous

Nonttomogeneous

Runways and

H

T

Aprons

H

H

taxiways Runways and

H

H

Aprons

L

LARGE AND M E D I U M AERODROMES * taxiways

INTERMEDIATE AERODROMES**

SMALL AERODROMES*** taxiways Runways and

L

L

Aprons

L

L

Protection

* ** ***

T = Total

= a n n u at lr a f f iecx c e e d i n g = a n n u a lt r a f f i cf r o m = a n n u a lt r a f f i c

H = High

L = Low

200 000 p a s s e n g e r s

50 000 t o 200 000 p a s s e n g e r s

less t h a n 50 000 p a s s e n g e r s

ICAO 9357 PART*K3

**

W 4 8 4 S q 5 b 0019489 7 2 8

3-114

.

4 2.8

Aerodrome Design Manual Allowable loads

4.2. 8.1 k t e r m l n i n gt h ea l l o w a b l el o a d sf o re x i s t i n g pavements la a r e c i p r o c a l problem of t h e d e s i g n p r o c e s s . A c t u a l l y , t h r e e t y p e s o f q u e s t i o n s are covered by t h i s heading, namely:

a)

as r e g a r d s a s p e c i f i c pavement, how t o p u b l i s h i n f o r m a t i o n b e a r i n g s t r e n g t h I n term of i t s c h a r a c t e r i s t i c s ;

b)

conversely, how c a n t h e a l l o w a b l e l o a d f o r e v e r y a i r c r a f t b e d e t e r m i n ed from this information (which has been established in a synthetic manner 1; and

c)

under what conditions should concessions be granted if the loads exceed the allwable loads.

Moreover, i n France two s y s t e m s f o r t h e p u b l i c a t i o n o f i n f o r m a t i o n o n s t r e n g t h e x i s t s i d e by s i d e , 1.e.

4.2.8.2

It i s i n t e n d e idtnh isse c t i o n

runway b e a r i n g

to:

two methodsand

b) Specify interim measures required s i d e by s i d e ; a n d

P u b l i s h i ni g nformation

t h e c o n d i t i o n s i n w h i c ht h e ya r e

as a r e s u l t of u s i n g t h e two methods

c> i n d i c a t e t h e c a l c u l a t i o n p r o c e s s u s e d should be granted.

a)

actual

t h e method based on a t y p i c a l u n d e r c a r r i a g e l e g a p p l i e d i n F r a n c e u p t o now; and

a)describeeachofthe used;

4.2.8.3

on i t s

i n d e c i d i n g when concessions

on runway b e a r i nsRt r e n g t h

Method based on t y p i c a lu n d e r c a r r i a g e le& S i n c e p r a c t i c a l l y a l l or modern a i r c r a f t are e q u i p p e d w i t h u n d e r c a r r i a g e s w i t h s i n g l e , d u a l d u a l tandem wheel a r r a n g e d n t s , t h e maxlmum l&d allowable on each pavement w i l l have t o be f i x e d f o r e a c h of t h e t h r e e t y p i c a l u n d e r c a r r i a g e s on t h e b a s i s of t e n movements per day over ten y e a r s .

Example:

20 t in r e s p e c t of t h e s i n g l e w h e e l , 35 t I n r e s p e c t of t h e d u a l wheel and 50 t i n r e s p e c t of t h e d u a l tandem wheel arrangements are e x p r e s s e d s y m b o l i c a l l y as follows:

The c h a r a c t e r i s t i c s of t h e t y p i c a l u n d e r c a r r i a g e l e g s are s e l e c t e d from t h e most c r i t i c a l l a n d i n g g e a r c h a r a c t e r i s t i c s o f c u r r e n t

ICAO 9357 PART*3

**

4 8 4 3 4 3 b 0039490 4 4 T W

3-115

E a r t 3 . - Pavements

a i r c r a f t (see 4.2.2). This methodof f i x i n gt h ea l l o w a b l el o a d sh a s the disadvantage of ignoring the variations which in fact exist w i t h i nt h e same c a t e g o r y of undercarriage.Forexample, I€ t h et r a c k of t h e d u a l w h e e l s o r t h e t i r e p r e s s u r e i s d i f f e r e n t f r o m t h a t of t h e typical undercarriage, the effect on t h e pavement w i l l d i f f e r c o n s i d e r a b l y f o r t h e same massof a i r c r a f t .S t r i c t l ys p e a k i n g , therefore, an allowable load according to aircraft type should be e s t a b l i s h e d f o r a g i v e n pavement. O b v i o u s l y ,t h i s method cannotbe a p p l i e di np r a c t i c e . However, wheneversuch a precise c a l c u l a t i o n i s j u s t i f i e d (e.g., f o rt h ep u r p o s e of c o n c e s s i o n s ) ,t h ee x a c tl a n d i n g g e a r c h a r a c t e r i s t i c s are t a k e n i n t o a c c o u n t , s o t h a tt h i sd o e sn o t d e p r i v e c e r t a i n a i r c r a f t of t h e a d v a n t a g e s t h e y d e r i v e f r o m t h e d e s i g n of t h e i r u n d e r c a r r i a g e . b)

ACN-PCN method

Note. - This method is described in Anne,?:14 and in f i q t e r 1 of !-his manuat. . 4.2.8.4 Choice of a method. The ACN-PCN method came i n t of o r c e for A I P s on 26 November 1981 a n d is g r a d u a l l y r e p l a c i n g t h e method based on a t y p i c a l u n d e r c a r r i a g e leg.

aE) x i s t i n p gavements

-

A f i n a l PCN w i l l b e p u b l i s h e d f o l l o w i n g t h e c o m p l e t e e v a l u a t i o n of pavementsundertheconditionsdescribed i n S e c t i o n 4.2.9, and t h i s w i l l r e p l a c e p u b l i c a t i o n s b a s e d on a t y p i c a l u n d e r c a r r i a g e l e g .

-

An i n t e r i m PCN w i l l b e p u b l i s h e d p e n d i n g a n e v a l u a t i o n , t o g e t h e r w i t h t h e e x i s t i n g method of r e p o r t i n g d a t a b a s e d on a t y p i c a l undercarriageleg.

b) Reinforced pavements

c)

A f i n a l PCN w i l l b ep u b l i s h e df o l l o w i n gt h ec o m p l e t er e i n f o r c e m e n t of a pavement; t h i s w i l l r e p l a c e p u b l i c a t i o n s b a s e d on a t y p i c a l undercarriage leg for the old pavement.

New pavements

-

A f i n a l PCN w i l l b e p u b l i s h e d f o r

new pavements.

Remark: I n areas s u b j e c t t o pronouncedseasonal climatic c h a n g e s ,t h e i n thecourse bearingstrengthofthesubgradecanvaryconsiderably of t h ey e a r .T h i s may n e c e s s i t a t e r e p o r t i n g two sets of PCN v a l u e s , one for the dry and one for the w e t season.

3-116

4.2.8.5

Aerodrome Design Manual C a l c u l a t i nt h gvea l u eb tposeu b l i s h e d a)Requireddata. The d a t ar e q u i r e df o rp u b l i s h i n gi n f o r m a t i o no np a v e ment s t r e n g t h c o n s i s t o f :

- total equivalent thickness and the

CBR oE t h e s u b g r a d e € o r f l e x l b l e

pavements.

- thickness

of t h e s l a b , p e r m i s s i b l e f l e x u r a l g r a d e r e a c t i o n k f o r r i g i d pavements.

Such d a t a are o b t a i n e d i n t h e c a s e

stress, modulusof

sub-

of:

- o l d pavements:fromanevaluationofbearingstrengthunder c o n d i t i o n s d e s c r i b e d i n 4.2.9.

- reinforcedpavements:fromtheevaluation

o f t h eb e a r i n gs t r e n g t h priortoreinforcementandfromthecharacteristicsadoptedin designing the reinforcement.

- new pavements:

f r o mt h ec h a r a c t e r i s t i c sa d o p t e d€ o rt h ed e s i g nw i t h of t h e a c t u a l c o n s t r u c t i o n . possiblecorrectionstotakeaccount

Calculation b)

- Method based

on a t y p i c a l u n d e r c a r r i a g e . The p e r m i s s i b l e l o a d Po f o r a t y p i c a l u n d e r c a r r i a g e l e g is o b t a i n e d by u s i n g t h e r e v e r s e d e s i g n method which consis ts-of determining from- graphs o r formulas t h e l o a d i n term o f t h e c h a r a c t e r i s t i c s of thesubgradeandthe pavement.

- ACN-PCN

Method. Determlningthe PCN i s a long andcomplex successive o p e r a t i o n . The c a l c u l a t i o n si n v o l v et h ef o l l o w i n g steps:

Step 1

- Establishing a

Step 2

- Calculating,withtheaidofthereversedesignmethod,

.

l i s t of a t r c r a f t w i n g o r pavement under study

likely to use the

t h ep e r m i s s i b l eP o i of t h e v a r i o u s a i r c r a f t i n terms o f t h e c h a r a c t e r i s t i c s ofthesubgradeandthepavement.

Step 3

- Ccorresponds alculating for each typical soil category the ACN which t ot h ep e r m i s s i b l e l o a d Poi. Subsequently, i n eachcategoryoneconsidersthe PCN included between the maximm and mlntrmm ACN valuesobtained. The PCN i s expressed by two s i g n i f l c a n t f i g u r e s .

Step 4

- Searching

among t h e c o u p l e s (soil c a t e g o r y , PCN) f o r t h e v a l u e t h a t w i l l produce permissible l o a d s P ' o i t h a t a r e c l o s e s t t o Poi.

P a r t 3.- Pavements

3-117

--

____--

.

3sualLythecalculationresultsin a s u b g r a d ec a t e g o r yt h a tc o n t a i n st h e CBR o r modulus k v a l u e3 ft h e pavement understudy. However, i t i s n o tu n u s u a lt oo b t a i na na d j a c e n t s u b g r a d ec a t e g o r ya n dt h ec l a s s i f i c a t i o nt h u sd e t e r m i n e d must be i n t e r p r e t e d " w i t h i n t h e a e a n i n g of t h e ACN-PCN method". c)

-

t y p e ofpavement: t h ec l a s s i f i c a t i o n t h e c r i t e r i a i n 4.2.1.1.

i s e s t a b l i s h e da c c o r d i n gt o

-

c a t e g o r y of s u b g r a d es t r e n g t h :t h i s i s provided a t t h e a s t h e PCN by t h e c a l c u l a t i o n d e s c r i b e d above.

-

maximum a l l o w a b l e t i r e p r e s s u r e : Code W (no p r e s s u r el i m i t a t i o n ) w i l l g e n e r a l l y be adopted. Code X ( p r e s s u r el i m i t e dt o 1.5 MPa) i s adopted where there i s a p r o v e n r i s k of s u r f a c e damage.

-

e v a l u a t i o n method: t h e PCN i s c a l c u l a t e df o l l o w i n g a complete Code U canonlybe e v a l u a t i o n : Code T w i l l normally be adopted. a p p l i e d f o r a2 i n t e r i m p u b l i c a t i o n of t h e PCN of a pavement f o r by d e t a i l e d e v a l u a t i o n w h i c h t h e r e are no r e l i a b l e r e s u l t s o b t a i n e d and whose behaviour has been judged on t h e b a s i s of i t s a b i l i t y t o accept existing traffic.

Remarks:

same time

homogeneous areas canbe be distinguished in regard to bearing strength, the values to published are the lowest obtained over the entire pavement area.

1) For a runway f o r w h i c hs e v e r a l

2)

4.2.8.6

which f o l l o w t h e PCN a r e s e l e c t e d i n t h e f o l l o w -

The f o u r c o d e l e t t e r s i n g manner:

I f a n area i s amenable t o a r e d u c t i o n i n t h e normal d e s i g n 4.2.2.2), weighting i s a l s o u s e d i n c a l c u l a t i n g t h e l o a d( s e e allowable loads.

Usingthepublishedvalues a )D e t e r m i n a t i o no fa l l o w a b l el o a d s :

1) ACN-PCN method. The a l l o w a b l el o a d Po of a n a i r c r a f t i s c a l c u l a t e d o n t h e b a s i s of t h e p u b l i s h e d PCN by t h e r e l a t i o n : PCN

Po = m + (M - m ) . max max ACN:

SeeAppendix

ACN

ACN v a l u e c o r r e s p o n d i n g t o t h e

min ACN:ACN eQ4J tY)

*

- min ACN ACN - min

5 , T a b l e 5-1.

valuecorrespondingtothe

[ 41 maximum mass* minimum mass ( o p e r a t i n g mass

2) T y p i c a lu n d e r c a r r i a g el e g

method. The a l l o w a b l e Load Po o n t h e i s t h a t which i s undercarriage leg of the aircraPt under study p u b l i s h e d i n r e s p e c t of t h e c o r r e s p o n d i n g t y p i c a l U n d e r c a r r i a g e leg.

Remark:

b)

In t h e case oE t h e pavement flJr whichboththe load p e r t y p i c a l u n d e r c a r r i a g e l e g and a PCN a r e p u b l i s h e d , o n e a d o p t s t h e h i g h e s t v a l u e o b t a i n e d by u s i n g one o r t h o q t h e r method.

Use of a l l o w a b l el o a d s :

-

-

i f t h e a c t u a l l o a d P is less t h a n t h e a l l o w a b l e l o a d Po t h e r e i s no r e s t r i c t i o n ( l o a d , number of m v e m e n t s ) f o r t h e a i r c r a f t u n d e r s t u d y w i t h i n t h e o v e r a l l f a t f g u e limit of t h e pavement. i ft h ea c t u a ll o a d carried out which aircraf t :

P exceeds Load Po:

may h a v e t h e f o l l o w i n g

a special s t u d y m s t b e results €or the subject

no r e s t r i c t i o n l i m i t e do p e r a t i o n "( a sr e g a r d s concession)

mass o r number of movements under a

r e f u s a l of a c c e s s

Example

teristics:

& t e r m i n a t i o n of PCN of a € l e x i b l e runway w i t h the f o l l o w i n g c h a r a c t o t ael q u i v a l e ntth i c k n e s s e = 7U c m CBR of subgrade

CBK = 8

The pavement receives t r a f f i c c o n s i s t i n g a l m o s t e x c l u s i v e l y Airbus A-300 B2, B-747-100.

of B-727-200, Standard,

Solution S t e p 1. The subgrade may b e c l a s s i f i e d in Category B ( m e d i u m s t r e n g t h ) as w e l l as i n Category C (low s t r e n g t h ) . These two c a t e g o r i e s w i l l t h e n be t e s t e d i.3 a s u b s e q u e n tc a l c u l a t i o n ,

*

See 2 . 2 . 2 . 2

f o rg u i d a n c eo nt h i s

issue.

P a r t 3.- Pavements

3-119

S t e p 2. C a l c u l a t i o no fa l l o w a b l el o a d sb a s e do nF r e n c hp r a c t i c e( u s e g r a p h s i n Appendix 3 ) :

of

P e r c e n t a g e of t o t a l mass on each main

main Load o n each A i ur cnrdaefrtucna d rl reigraT cgo aertl a reilga g e

A-300 B2 B-727-200

(Standard)

B-747-100

mass

66 t

142

46.5

t

39 t

84

46.4

t

23

t

7 6 t 329

.l25

S t e p 3. C a l c u l a t i o n of t h e ACN c o r r e s p o n d i n gt ot h ea l l o w a b l el o a d determined f o r e a c h a i r c r a f t

.

CATEGORY B

A-300 B2

ACN = 23*

+

(45

-

23)

. 142 000 - 8 56 9 0 142 000

-

B-727-200 (Standard)

ACN = 2 2

+

(43

-

22)

- 44293 . 87484000 7 1 - 44293

B-747-100

ACN = 20

+

(50

-

20)

. 329 3 3 47 5 1

000

=

45

85690

-

1 6 27 0 3

-

162703

= 46

49

=

CATEGORY C

A-300 B 2

ACN = 26

+

(55

-

26)

000 - 8 56 9 0 . 142 142 000 - 85690

B-727-200 (Standard)

ACN = 24

+

(49

-

24)

. 87484 7 1

B-747-100

ACN = 2 2

+

(60

-

22)

000

-

55

4 4 293 =

53

- 44293

. 329 000 - 1 6 27 0 3 3 3 47 5 1

=

-

=

59

162703

S t e p 4 . The PCN v a l u et ob ed e t e r m i n e dr a n g e sf r o m 4 5 t o 49 i f oneadopts Category B andbetween 5 3 and 59 f o rC a t e g o r y C. It is n o t e d ,h o w e v e r ,t h a tt h e B-727 is a c c e p t a b l e i n b o t h cases a t a l o a de x c e e d i n gt h e maximum all-upmass. When c o n s i d e r i n g t h e A-300B2 and t h e B-747-100 o n l y , t h e c h o i c e is l i m i t e d w i t h i n t h e r a n g e 55 t o 59 f o r C a t e g o r y C.

*

S e e Appendix 5 , T a b l e 5-1.

Aerodrome Desirn Manual

3-120 Step 5. The f i n a l c h o i c e i s made betweenthe PCN = 57 o b t a i n e d f o r C a t e g o r i e s B and C r e s p e c t i v e l y . Allowable load deduced from t h e PCN Category B PCN = 47 Category C PCN = 57

-

"True" a l l w a b l e load

147.2 t 317.5 t

142 t 329 t

+ 5.2 t -11.5 t

A-300 B2: B-747-100

145.8 t 321.2 t

142 t 329 t

+ 3.8 t 7.8 t

-

The d i f f e r e n c e between t h e a l l o w a b l e l o a d s c a l c u l a t e d methods is less in t h e s e c o n d ca6er Step 6.

Dif Eerence

B-747-100:

A-300 B2:

-

mean v a l u e s PCN = 47 and

by means of t h e two

Publication PCN 57/F/C/W/T

4.2.9

Evaluation ofpavements

4.2.9.1 General. Evaluation of existing pavements e n s u r i n g e f f i c i e n t u t i l i z a t i o n of t h e i r p o t e n t i a l . follows:

is an i n d i s p e n s a b l teo oiln

It f u l f i l s t h r e e m a i no b j e c t i v e s ,

as

o r more e x t e n s i v e work m s t

a)

t o determine when maintenance operations be undertaken;

b)

a t t h e time s u c h work ha6 t o b e u n d e r t a k e n , t o a s s e s s t h e r e s i d u a l q u a l i t i e s of t h e pavement w i t h a view t o e n a b l i n g a t e c h n i c a l a n d economic s o l u t i o n t o b e f o u n d a n d t h e d e s i g n f o r a possible reinforcement t o bedetermined;and

c)

t o d e t e r m i n e , a t any time, which a i r c r a f t t y p e s c a n u s e a p a r t i c u l a r pavement,and t h e i r mass and rnaxiuun movement frequency (allowable l o a d s d e s c r i b e d i n 4.2.8).

4.2.9.2 Pavement e v a l u a t i o nm u s t a k ei n t oa c c o u n bt o t ht h es t r u c t u r a al n d f u n c t i o n a l c h a r a c t e r l s t i c s of t h e pauements. The s t r u c t u r a l c h a r a c t e r i s t i c s of t h e pavement/subgrade complex govern i t s b e a r i n g s t r e n g t h , i.e.,its a b i l i t y t o b e a r l o a d s imposed by a i r c r a f t w h i l e r e t a i n i n g i t s s t r u c t u r a l i n t e g r i t y d u r i n g a c e r t a i n l i f e . The functional characteristics affect the state of the pavement s u r f a c e a n d t o what e x t e n t t h e pavement can be safeby used by a i r c r a f t . They a r e : of t h e l o n g i t u d i n a l p r o f i l e a n d , in p a r t i c u l a r , the a)thequality evenness which determine the degree of vibrations produced i n a i r c r a f t during roll out; b)

s l i p p e r i n e s s ,w h i c hd e t e r m i n e st h ed e g r e e brakingoftheaircraft;and

a€ directionalcontroland

I C A O 9357 P A R T * I t t

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4 8 4 3 4 3 6 0039476 9 b 8

Part 3 . - Pavements

Moreover, the structural and functional characteristics are not independent: thus, the state of the surface can reveal possible structural defects and, conversely, a structur of the surface. unsuited to the traffic causes deterioration 4.2.9.3 synthesis by

Evaluation of pavements is a-verycomplex procedure a specialist team of the following elements:

which

calls

for

a

a)

data on the design of the pavement and of the subsoil, as on well as possible subsequent work (maintenance, reinforcement, etc.);

b)

study of the aerodrome site;

c)

climatological data (hydrology, ground water, frost, etc.);

d)

visual inspections of the state of the pavement, surveying the deterioration and examining the drainage;

e)

various measurements which enable certain parameters associated with the pavement characteristics (evenness, slipperiness, bearing strength) to be determined; and

f)

measurement of the thickness and qualitative assessment of the pavement courses and the characteristics of the subgrade.

4.2.9.4 The following paragraphs deal only with the evaluation of the pavement bearing strength. The purpose of this evaluation is to assign the following representative structural parameters an to existing pavement to represent its current bearing strength which can be directly applied to determine the allowable load reinforcement required:

4.2.9.5

a)

the CBR of the subgrade and the total equivalent thickness for a flexible pavement; and

b)

the modulus of reaction k of the subgrade, thickness of the concrete slab and the permissible flexural stress of the concrete in of a rigid pavement.

the

Two approaches may be used to determine these parameters, as follows:

a) by a procedure which is the exact reverse of the design process, the ' so-called "reverse design method"; and b)

by means of non-destructure plate loading tests on the surface of the pavement which indicate the actual allowable in load the case of a single wheel leg.

In practice, the evaluation of a pavement bearing the resultsof these two complementary approaches.

strength

must bybesynthesizing made

and

case

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4.2.3.6 Reverse design method. The purpose of t h de e s i g n method d e s c r i b e d p r e v i o u s l y which u s e s t h e s u b g r a d e d a t a , i s t o d e t e r m i n e a pavement s t r u c t u r e t h a t c a n b e a r a g i v e n t r a f f i c o v e r a c e r t a i n l i f e , provided"normal"mal-ktenance is performed. Conversely, once the characteristics of the subgrade and o f t h e pavement s t r u c t u r e are known, t h i s method e n a b l e s t h e t r a f f i c w h i c h c a n b e a c c e p t e d d u r i n g a g i v e n time t o be determined. The f o r e g o i n g i s t h e basis f o r e v a l u a t i o n bearing s t r e n g t h by Mans of t h e r e v e r s e d e s i g n method. When t h i s method i s used by itself , however, c o n s i d e r a b l e d i f f i c u l t i e s are encountered i n d e t e r m i n i n g t h e s t r u c t u r a l parameters t h a t rmst be taken i n t o a c c o u n t i n e v a l u a t i n g a n e x i s t i n g pavement and i t s subgrade. Even if records are a v a i l a b l e of t h e c o n s t r u c t i o n of t h e p a v e r e n t , of any maintenance and reinforcement work perforaed in the past, and of t h e t r a f f i c a c c e p t e d , t h i s method r e q u i r e s many t r i a l borings and testings of the paveaent. Moreover, t h e r e w i l l u s u a l l y b e some u n c e r t a i n t y concerning the results because of the difficulty of e v a l u a t i n g c e r t a i n p a r a m e t e r s a f l e x i b l e pavement, load transfers between ( e q u i v a l e n c e c o e f f i c i e n t s of the courses of c o n c r e t e s l a b s , etc. 1.

Remark: The r e v e r s e d e s i g n method canonly be u s e d f o r a pavement t h a t i s correctly constituted (for flexible pavements, t h e c o u r s e s must b e o f i n c r e a s i n g q u a l i t y from bottom t o t o p and adhere closely).

4.2.9.7 Non-destructive plate tests. When i n t e r p r e t e d by q u a l i f i epde r s o n n e l , a single wheel n o n - d e s t r u c t i v e p l a t e tests c a n d i r e c t l y p r o v i d e t h e a l l o w a b l e l o a d f o r a t a l a r g e number of points on a f l e x i b l e pavement and the a l l o w a b l e l a a d a t t h e c o r n e r s of slabs i n t h e case of a r i g i d pavement. These tests are i n s u f f i c i e n t t o d e t e d n e t h e allowable load f o r a i r c r a f t w i t h m u l t i p l e wheel u n d e r c a r r i a g e s o r t o s e r v e a s t h e b a s i s f o r d e s i g n i n g a reinforcement, in which case t h e r e v e r s e d e s i g n method must be adopted. tests considerably reduce the number of d e e t r u c t i v e tests Nevertheless, the plate required in order to apply a reliable cross-check i n t h e case of f l e x i b l e pavementsand e n a b l e t h e q u a l i t y of t h e l o a d t r a n s f e r t o be e v a l u a t e d i n t h e c a s e of rigid pavements, as explained i n t h e f o l l o v i n g p a r a g r a p h . 4.2.9.8 Test programme t o e v a l u a tbe e a r i n sgt r e n g t h . The amount of equipment required depends on t h e p a r t i c u l a r o b j e c t i v e a n d how rmch i s a l r e a d y known a b o u t t h e pavement:

a> If t h e pavement i s o l d a n d l i t t l e i s known of t h e equipment described below m s t be used. b)

characteristics, all

I€ t h e pavement i s of recentconstructionandadequaterecords are a v a i l a b l e o r t h e pavement h a s a l r e a d y b e e n t h e s u b j e c t o f a cow in prehenvive evaluation of the type described above and changes b e a r i n g s t r e n g t h o n l y are t o be determined, non-destructive plate tests are usually adequate. This a l s o a p p l i e s t o a pavementwhich h a s undergone a c o n p l e t e e v a l u a t i o n f o l l w e d by r e i n f o r c e m n t work,where the r e s u l t s of such work are t o b e checked.

The following paragraph6 deal with the

4.2.9.9

it6

f i r s t c a s e , i.e.? a complete study.

D e l i n e a t i o n of homogeneous zones a > The f i r s t phase of t h e s t u d y is i n t e n d e d t o d e l i n e a t e t h e zones whose s t r u c t u r e a n d s t a t e are i d e n t i c a l a n d t o assess t h e i r homogeneity i n o r d e r t o r e d u c e t h e number OP o t h e r tests needed t o d e t e r m i n e t h e pavement s t r u c t u r e . To c o m p l e t et h ei n f o r m a t i o na v a i l a b l ef r o mt h e

i I

I C A O 7357 P A R T * 3

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P a r t 3 . - Pavements

3-123

r e c o r d s , a d e t a i l e d v i s u a l i n s p e c t i o n of t h e pavement must f i r s t be performed,including a s u r v e y a n d c l a s s i f i c a t i o n of i t s d e t e r i o r a t i o n , as w e l l as an i n s p e c t i o n of the drainage system. b)During

a s e c o n ds t a g e ,t h ef o l l o w i n g

may beused:

For f l e x i b l e pavements: e i t h e rt h eL a c r o i xd e f l e c t o g r a p h o r t h e i n f l u o g r a p h of t h e STBA". F o rr i g i dp a v e m e n t s :t h ee q u i p m e n tf o rm e a s u r i n gv i b r a t i o n (DMBD) of t h e LCPC.

of t h e LCPC,

of s l a b s

c )F i n a l l y , a r e l a t i v e l y l a r g e numberof n o n d e s t r u c t i v e p l a t e tests (from 80 t o 100 o n a medium-size aerodrome) are performedwhichnot as onlyenablethehomogeneityof pavement b e h a v i o u r t o b e a s s e s s e d , i n t h e case oftheabove-mentionedequipuent,butwhichalsogivethe value of the allowable load for a s i n g l e w h e e l a t e a c h of t h e s e points. All the above-mentioned equipment 4.2.9.10 D e s c r i p t i o n of t h e homogeneous zones. i s used t o d e f i n e t h e homogeneous zones on t h e b a s i s of t h e i r s t r u c t u r e a n d b e h a v i o u r . H a v i n gd e t e r m i n e dt h ea l l o w a b l el o a d Po f o r e a c h homogeneous z o n e , o n e o r s e v e r a l are performed a t one o r boringsmustbeperformed t o e v a l u a t e e a c h zone.Theseborings a result P i close to the s e v e r a l p o i n t s a t which p l a t e t e s t s were c a r r i e d o u t p r o d u c i n g Some b o r i n g s are o c c a s i o n a l l ya l s op e r f o r m e d a l l o w a b l el o a d Po a d o p t e df o rt h a tz o n e . a t s p e c i f i cp o i n t s( e . g . , w h e r et h ea l l o w a b l el o a d P i i s p a r t i c u l a r l y low). A s a no r d e r ofmagnitude, a t o t a l of 6 t o 12 t r i a l b o r i n g s are u s u a l l y s u f f i c i e n t f o r a medium s i z e aerodrome,dependingonthehomogeneity of t h e pavements t e s t e d . These t r i a l b o r i n g s must c o v e r a s u r f a c e area of a p p r o x i m a t e l y 1.5 m2 and are performed:

a )t od e t e r m i n et h es t r u c t u r e of t h e pavement, p a r t i c u l a r l y t h e t h i c k n e s s of t h e c o u r s e s a n d t o c h e c k t h e q u a l i t y of t h e materials encountered, if necessary in the laboratory; b )t ou n d e r t a k e CBR t e s t s in s i t u o r t e s t s of t h e modulus of s u b g r a d e r e a c t i o n k whenever possible; and c )t om e a s u r et h em o i s t u r ec o n t e n ta n dd r yd e n s i t y of thesubgradeand tests. take intact or treated samples for laboratory analysis and

to

4.2.9.11 I n t e r p r e t a t i o n and s y n t h e s i s of t h ree s u l t s . The r e s u l t fsoer a c h homogeneous zone are i n t e r p r e t e d i n t h e l i g h t of t h e d a t a i n respect of t h e pavementand t r a f f i c i t h a sa c c e p t e d ,t h es u r v e y s of i t s d e t e r i o r a t i o n , t h e r e s u l t s of. t h e i n s p e c t i o n of t h e d r a i n a g e s y s t e m and a l l t h e measurementsperformed.Thissynthesis must be c a r r i e d o u t by a s p e c i a l i s t team, i n p r a c t i c e t h e STBA. Cross-checking of t h e d i f f e r e n t measurementvalues p e r m i t s making a f i n a l c h o i c e of t h e d i f f e r e n t c h a r a c t e r i s t i c s requiredtocalculatetheallowableloads(see 4.2.8).

*

..-

STBA:

S e r v i c eT e c h n i q u ed e s

Bases A g r i e n n e s ,M i n i s t b r ed e sT r a n s p o r t s ,F r a n c e

ICAO 9157 P A R T 8 3 t t

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4 B Y L 4 L b OOL9499 677 W

Manual

Aerodrome Design

Painforcement ofpavements

4.2.10.1 General. The problem of reinforcement of aerodrome pavements can arise when manoeuvring areas m s t b e a d a p t e d t o w e t t h e f u t u r e r e q u i r e n e n t s o f h e a v i e r airc r a f t o r when pavements r e q u i r e s t r e n g t h e n i n g t o meet inmediate needs of c u r r e n t two concerns are frequentlyconfused.Reinforcement is not t r a f f i c . In p r a c t i c e ,t h e s e the only solution, however, i f a p a r t i c u l a r pavement i s n o t s u i t e d t o t h e p r e s e n t o r future traffic:

- It may a t

times b e p r e f e r a b l e t o b u i l d a new pavementsomewhere else. This solution obviates the difficulty of maintaining the flow of t r a f f i c d u r i n g t h e r e i n f o r c i n g work; i t a l s o a l l o w s f o r t h e i n t r o d u c t i o n o f a n improved l a y o u t more a d a p t e d t o new o p e r a t i n g c o n d i t i o n s .

- The

" s u b s t i t u t i o n " method c o u l da l s ob ea d o p t e d . This c o n s i s t s of removing t h e e x i s t i n g pavement and rebuilding a new one a t t h e same l e v e l . This s o l u t i o n , w h i c h i n t h e case of a runway can be l i m i t e d t o 15 m o n e i t h e r s i d e of t h e c e n t r e l i n e , a v o i d s m e r g i n g p r o b l e m s . Howi t i s t h e most expensive one. ever,of a l l the possible solutions,

o f p a v e ~ e n t s ; i t d e s c r i b e s a method The t e x t below d e a l s w i t h t h e a c t u a l r e i n f o r c e m e n t for determining the thickness of the reinforcement and deals w i t h c e r t a i n r e l e v a n t problems encountered during construction. 4.2.10.2 Choice of s o l u t i o n . The r e i n f o r c e m e nfto r a p a r t i c u l a r pavement ( f l e x i b l e orrigid)canbe of t h e same t y p e o r d i f f e r e n t . The c h o i c e i s governed by t e c h n i c a l a n d economic considerations, by t h e r e s t r i c t i o n s imposed by t h e s o l u t i o n on t h e u s e o f t h e aerodrome while the work i s b e i n g c a r r i e d o u t a n d by t h e bond between the reinforcement and the existing pavement. 4.2.10.3 Choice of t h ec r o s s - s e c t i o n apl r o f i l eA . p p r e c i a b l es a v i n g cs a nb e made i n a runway by r e d u c i n g t h e t h i c k n e s s of t h e pavement o u t s i d e a the cost of reinforcing 30 m w i d e c e n t r a l s t r i p a n d s u b j e c t t o c o m p a t i b i l i t y with t h e g e o m e t r i c a l s t a n d a r d s o f t h ec r o s s - s e c t i o n a lp r o f i l e .A p a r tf r o m a s a v i n g i n r e i n f o r c i n g material, t h e d e c r e a s e runway,sometimes down t o i n t h i c k n e s s of t h e r e i n f o r c e m e n t t o w a r d s t h e e d g e s o f t h e o r eveneliminatestheneed to r a i s e t h e l e v e l o f t h e s h o u l nothing, also minimizes ders. 4.2.10.4 The t h i c k n e s s of t h ef l e x i b l er e i n f o r c e w n t following relationship:

e = 3.75 (Fht

may beobtalnedusing

- h)

the [IS]

- in this relationship,

e is t h e e q u i v a l e n t t h i c k n e s s in accordance with It should bs n o t e d t h a t t h e aaterials t h e d e f i n - i t i o n g i v e n i n 4.2.3.4. used f o r a reinforcement ~ 1 s be t at l e a s t q 1 1 a 1i n q u a l i t y t o t h o s e u s e d coefficient of equivalence m s t be a t forthesubbasecourse,i.e.,the l e a s t 1;

-h -4

is t h e t h i c k n e s s

of t h e e x i s t i n g c o n c r e t e s l a b ;

i s thetheoreticalthickness of t h e new slab Less t h e e x i s t i n g s l a b . This t h i c k n e s s i s c a l c u l a t e dt a k i n gi n t oa c c o u n tt h ea l l o w a b l e stress a n d t h e c o r r e c t e d k a p p l i c a b l e t o t h e e x i s t i n g s l a b ;

I C A O 7357 P A R T t 3 t t

3-125

= 484143b

OOL75OO 317

=

Part 3 . - Pavements

-

F is a coefficient of reduction of the thickness hts the of value which is given in Figure 4-31 as a function of the modulus k already mentioned (the theoretical thickness of the concrete slab is reduced because it is assumed that the slab will crack to a certain extent service, in contrast with the assumption in made connexion with the calculation for slabs used in the wearing course);

in

- The

equivalent thickness of the reinforcement must not be less than 20 cm, unless special levelling courses are used to correct deformations. Because of the presenceo f joints and the movement of the slabs, the concrete will have to be covered with a layer of material of sufficient thickness to prevent the appearance of defects at the surf ace;

- Moreover,

the relationship at [5] is applicable only to values resulting in an equivalent thickness e exceeding 20 cm.

J

c

I 0

IO

20

30

40

50

I

I

60

70

80

90

I 100

110

Modulus of Reaction'K in MN/m3 Figure 4 - 3 1 .

Flexible reinforcementon rigid pavement- Factor F

4.2.10.5 Construction rules. The most pressing problem - and one which has not yet been satisfactorily resolved - associated with the direct reinforcement of concrete with a bituminous mix is that of the reappearance of the in joint the rigid pavement at the surface of the reinforcement. Attempts are made to prevent this damage by reinforcing at the pavement at these joints by means of metal lattices, plates, fabrics,oretc., of bituminous mix from the slab over a certain distance least by separating the course on either side of the joint (e.g.,by interposing a layer of sand). It is also possible to providesaw cut jointson the surface of the reinforcement to avoid irregular cracking. This solution facilitates maintenance, but reduces the bearing strength of the pavement

.

4.2.10.6

affinity

of

Although seldom encountered, another possible difficulty is caused by the of swelling certain jointing compounds for the bitumen, which can result in

I C A O 9557 P A R T t 3 t t

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Aerodrome Design Manual

If i n doubt, i t w i l l thenbeadvist h e pavement a t t h e j o i n t of t h e r e i n f o r c e d s l a b . a b l e t o remove t h e j o i n t i n g compound b e f o r e t h e r e f n f o r c e m e n t is a p p l i e d a n d t o r e f i l l the oneused i n t h e t h e j o i n t s w i t h a mixture of sand and binder compatible with r e i n f o r c i n gc o u r s e .T h e s er u l e sc a n n o tb ea p p l i e di nt h e case of r e i n f o r c e m e n tw i t h concrete,unlesstheconcrete is limited to the central portion of therunaayand a " f l e x i b l e " s o l u t i o n i s adopted i n t h e case o f t h e l a t e r a l p a r t s .

P r e l i d n a r ys t u d i e s . An e v a l u a t i o n of t h e x i s t i n g pavement is r e q u i r e d Of primeimportance i s a s y s t e m a t i c b o r i n g o f t h e p a v e m n t i n v i e w o f t h e etc. rlf t h e o l d pavements. frequentdiscrepanciesinthickness,constitution,

4.2.10.7 (see 4.2.9).

4.2.10.8

Reinforcement of f l e x i b l e pavements

is a1Flexiblereinforcement. The t h i c k n e s so ft h er e i n f o r c e m e n t determined by t h e d i f f e r e n c e between t h e e q u i v a l e n t t h i c k n e s s r e q u i r e d f o r a new pavement a n d t h a t of t h e e x i s t i n g pavement. When determini n g t h e latter, thefollowingshouldbetakenintoaccount: 1) t h e e q u i v a l e n c e c o e f f i c i e n t s h a v e t o b e c o r r e c t e d a c c o r d i n g t o t h e actual condition of the pavement courses; and

21

b)

4.2.10.9

t h ee q u i v a l e n c ec o e f f i c i e n t of a pavement course a t a g i v e n l e v e l cannot be g r e a t e r t h a n t h a t o f t h e c o u r s e a b o v e i t . F o ri n s t a n c e , i f a bituminous mix i n good c o n d i t i o n ( c o e f f i c i e n t 2) i s covered by a coarse-aggregate cement ( c o e f f i c i e n t 1.51, t h e c o e f f i c i e n t o f t h e f o r n e r a l s o becomes 1.5.

Rigidreinforcement. When a f l e x i b l e pavement is r e i n f o r c e dw i t h concreteslab,theformer i s onlyconsideredas a sub-basecourse t h ec a l c u l a t i o n s . The k valuewhich is a t t r i b u t e d t o t h i s c o u r s e determined by r e f e r e n c e t o F i g u r e 4-13. The t h i c k n e s s o f t h e s l a b thenestablishedinaccordancewith 4.2.4, 4.2.5, and 4 . 2 . 5 .

a in

is is

Reinforcement of r i g i d pavements a)

F l e x i b l er e i n f o r c e u e n t . If t h ee x L s t i n g pavement i s a p p r e c i a b l y Tragmented, i t i s a d v i s a b l e t o c o n s i d e r i t as a f l e x i b l e pavementof t h e same t h i c k n e s s when computing t h e t h i c k n e s s o € t h e r e i n f o r c e m e n t . It thusamounts t o t h e same c a s e as d e s c r i b e d a b w e . The d e s c r i p t i o n below p r e s u p p o s e s t h a t t h e e x i s t i n g r i g i d pavement is s t i l l sound ( i n that case it is still possible to consider the existing rigid pavement as a f l e x i b l e pavement of t h e same t h i c k n e s s i f t h t s i s f a v o u r a b l e t o thecalculations).

b11 Rigidreinforcement. The t h i c k n e s s of t h er e i n f o r c i n gs l a b obtained by applying the formula:

1.4 h,=

-

is

I ChlB4

i s t h et h e o r e t i c a lt h i c k n e s s of a new s l a bd e t e r a i n e du s i n gt h e modulus oE p e r m i s s i b l e stress i n t h e new c o n c r e t e a n d t h e c o r r e c t e d reaction for the existing subgrade.

I C A O 9357 P A R T * 3

P a r t 3.-

**

4 8 4 3 4 L b 0039502 T93

Pavements

3-127

-

h i s the thickness of the existing concrete slab.

-

C is a coefficient introduced in order to take account of the quality of the existing pavement:

C

=

1 f o r a pavement i n good c o n d i t i o n ,

C = 0.75 f o r a pavement e x h i b i t i n g some c r a c k i n g a t t h e c o r n e r s , b u t not appreciably deteriorated,

C = 0.35 f o r a badly fragmented pavement. I n practice o n e o f t h e

two l a t t e r v a l u e s a r e g e n e r a l l y a p p l i e d .

i s l a i d d i r e c t l y on t o p o f The a b o v e r e l a t i o n s h i p o n l y a p p l i e s i f t h e r e i n f o r c i n g s l a b a l a y e ro fm a t e r i a l( u s u a l l yb i t u m i n o u s mix) i s i n t e r p o s e d t h e e x i s t i n g pavement.If between the two s l a b s , e . g . i n o r d e r t o a l t e r t h e p r o f i l e of t h e e x i s t i n g pavement, t h e fornula for calculating the thickness of the reinforcement becornes: hr =

71

ht2

-

Ch2

71

In this expression, the significance of the parameters and the values for coefficient a r e t h e same as d e t a i l e d p r e v i o u s l y . T h i s f o r r m l a r e s u l t s i n s l i g h t l y i n c r e a s e d t h i c k nessesofthereinforcement.

C

4.2.10.10 C o n s t r u c t i o nr u l e s . To a v o i dt h er e a p p e a r a n c e of t h ej o i n t si nt h ee x i s t it i s essential that the i n g pavement i n t h e f o r m o f c r a c k s i n t h e r e i n f o r c i n g s l a b , Eloreover, a l l t h e j o i n t s i n t h e j o i n t s b e s u p e r i m p o s e d a s a c c u r a t e l y as p o s s i b l e . e x i s t i n g pavementmusthave new j o i n t s (ofanytype)above them. Inparticular,since t h e o l d s l a b s are g e n e r a l l y smaller i n w i d t h t h a n t h o s e c u r r e n t l y a d o p t e d , a d d i t i o n a l longitudinalcontraction-expansionjoints may b e n e c e s s a r y i n t h e r e i n f o r c i n g s l a b . The placement of t h e d i f f e r e n t r e i n f o r c i n g j o i n t s t h u s calls f o r a preliminary in-depth study if one wishes to avoid miscalculations. 4.2.11

Light pavements

4.2.11.1 Light pavements are i n t e n d e de x c l u s i v e l yf o ra i r c r a f t whose t o t a l mass d o e sn o te x c e e d 5.7 t o n n e s . F i g u r e 4-32 may b e u s e d t o c a l c u l a t e t h e pavementthickness i n r e l a t i o n t o t h e CBR o f t h e n a t u r a l s o i l . 4.2.11.2 Allowable loads. The a l l o w a b l leo a d on a l i g h t pavement i s 5 700 kg. The a i r c r a f t t i r e p r e s s u r e must n o t e x c e e d 0.6 MPa (approximately 6 kg/cm2) t o a v o i d any r i s k ofpunching.Consequently,theinformation tobepublishedon pavement s t r e n g t h i n a c c o r d a n c e w i t h t h e Annex 14 p r o v i s i o n s f o r l i g h t pavements w i l l b e 5 700 kg/O. 6 ma.

Aerodrome Design Hanual ~~

25

Thickness of pavement in cm (wearing course excluded)

F i g u r e 4-32.

Designing a l i g h t pavement

~

I C A O 7357 P A R T * 3

**

P a r t 3 . - Pavements

4.3

= 48414Lb

0039504 A b 4

3-129

United Kingdom p r a c t i c e

4.3.1

Design and evaluationofpavements

4.3.1.1 It i s t h eU n i t e d Kingdom p r a c t i c et od e s i g nf o ru n l i m i t e do p e r a t i o n a u l se of by a g i v e n a i r c r a f t t a k i n g i n t o a c c o u n t t h e l o a d i n g r e s u l t i n g f r o m i n t e r a c t i o n a d j a c e n tl a n d i n gg e a rw h e e la s s e m b l i e sw h e r ea p p l i c a b l e . The a i r c r a f t i s d e s i g n a t e d " t h ed e s i g na i r c r a f t "f o rt h e pavement. The s u p p o r t s t r e n g t h c l a s s i f i c a t i o n o f t h e pavement c l a s s i f i c a t i o n number i d e n t i f y i n g pavement i s r e p r e s e n t e d by t h e d e s i g n a i r c r a f t ' s i t s l e v e l o fl o a d i n gs e v e r i t y . All o t h e r a i r c r a f t r a n k e d b y t h e U n i t e d Kingdom s t a n d a r d s as less severe may a n t i c i p a t e u n l i m i t e d u s e o f t h e pavement t h o u g h t h e f i n a l d e c i s i o n rests w i t h t h e a e r o d r o m e a u t h o r i t y . 4.3.1.2 While t h e r ea r e now a v a i l a b l e a number ofcomputer programmes basedon plate theory,multilayer elastic theoryandfiniteelementanalysis,forthosewishingtohave readilyavailabletabulateddatafor pavement d e s i g n a n d e v a l u a t i o n , t h e R e f e r e n c e C o n s t r u c t i o n C l a s s i f i c a t i o n (RCC) s y s t e m h a s b e e n d e v e l o p e d f r o m t h e B r i t i s h Load are C l a s s i f i c a t i o n Number (LCN) and Load C l a s s i f i c a t i o n Group (LCG) systems.Pavements i d e n t i f i e d as d i v i d i n g b r o a d l y i n t o r i g i d o r f l e x i b l e c o n s t r u c t i o n a n d a n a l y s e d a c c o r d i n g l y .

e

4.3.1.3 For t h er e a c t i o no fa i r c r a f t on r i g i dp a v e m e n t s , a s i m p l e two l a y e r model i s adopted. To e s t a b l i s h a n a i r c r a f t ' s t h e o r e t i c a l d e p t h o f r e f e r e n c e c o n s t r u c t i o n on a rangeofsubgradesupportvaluesequatingtothe ICAO ACN/PCN r e p o r t i n g method, t h e model i s a n a l y s e db yW e s t e r g a a r dc e n t r e case theory.Account i s t a k e n of t h e e f f e c t of a d j a c e n t l a n d i n gg e a rw h e e la s s e m b l i e su pt o a distanceequaltothree times t h e r a d i u s of r e l a t i v e i s c o n s i d e r e de s s e n t i a li na n y new s y s t e mi nv i e wo ft h ei n c r e a s i n g mass stiffness.This ofaircraft,complexityoflandinggearlayoutsandthepossibleinteraction of a d j a c e n t wheel assemblies on p o o r s u b g r a d e s e s p e c i a l l y . 4.3.1.4 To r e s o l vper a c t i cda el s i gannedv a l u a t i opnr o b l e m s , a r a n eg oqef u i v a l e n c y factorsappropriatetothe r e l a t i v e s t r e n g t h so fi n d i g e n o u sc o n s t r u c t i o n materials is adoptedtoconvertbetweentheoretical model r e f e r e n c e c o n s t r u c t i o n d e p t h s a n d a c t u a l pavement t h i c k n e s s . 4.3.1.5 A i r c r a f t r e a c t i o n on f l e x i b l e pavementsfollowsthe same b a s i c p a t t e r n a d o p t e d f o r r i g i d p a v e m e n td e s i g na n de v a l u a t i o n .I nt h i sc a s e a f o u r pavementmodel i s a n a l y s e d u s i n gt h eU n i t e dS t a t e sC o r p so fE n g i n e e r s rd e v e l o p m e n to ft h eC a l i f o r n i a B e a r i n gR a t i o (CBR) m e t h o d .T h i si n c l u d e sB o u s s i n e s qd e f l e c t i o nf a c t o r sa n d takes intoaccountinteractionbetweenadjacentlandinggearwheelassemblies up t o 20 r a d i i are r e s o l v e du s i n ge q u i v a l e n c y d i s t a n c e .P r a c t i c a ld e s i g na n de v a l u a t i o np r o b l e m s model on which f a c t o r s t o r e l a t e materials a n d l a y e r t h i c k n e s s e s t o t h e t h e o r e t i c a l are a s s e s s e d . the reference construction depths for aircraft 4.3.2

R e p o r t i n g pavement s t r e n g t h

4.3.2.1 It i s the United Kingdom p r a c t i c et of o l l o wt h e ICAO ACN/FCN r e p o r t i n g method f o r a i r c r a f t pavements. The c r i t i c a l a i r c r a f t i s i d e n t i f i e d as theonewhich maximum p e r m i t t e d o n a g i v e n imposes a s e v e r i t y of l o a d i n g c o n d i t i o n c l o s e s t t o t h e pavement f o r u n l i m i t e d o p e r a t i o n a l u s e . Usingthe c r i t i c a l a i r c r a E t ' s ACN i n d i v i d u a l PCN t o b e p u b l i s h e d f o r t h e pavement concerned. aerodrome a u t h o r i t i e s d e c i d e o n t h e

3-130

Manual

~~

Aerodrome Design

4.3.2.2 Though n o t r e v e a l e db yt h e ICAO ACX/PCS r e p o r t i n g method, when i n t e r a c t i o n betweenadjacentlandinggearwheelassembliesaffectsthelevelofloading imposedby a n a i r c r a f t , U n i t e d Kingdom aerodrome a u t h o r i t i e s nay impose r e s t r i c t i o n s on o p e r a t i o n s by a mass l i m i t a t i o n o r a r e d u c t i o n i n t h e number of p e r m i t t e d movements. This is unlikely to occur, however, with aircraft currently in operational use except where are poor. subgradesupportvalues 4 . 4U n i t e dS t a t e so f

America P r a c t i c e

Note. - fizq spectfierztiotzs -it: this Z S ? - ? & ~ :C& ~ ~ L ~ cqhubatim~lcz+. 4.4.26.3

B i t u m i n o uosv e r l a yosenx i s t i nfgl e x i b l e a)

a minimum

pavement

Use t h ea p p r o p r i a t eb a s i cf l e x i b l e pavement curvestodetermine a f l e x i b l e pavement f o r t h e thethicknessrequirementsfor d e s i r e dl o a da n d number ofequivalentdesigndepartures. A CBR v a l u e is r e q u i r e df o rt h es u b g r a d e material andsub-base.Thicknesses of a l l pavement l a y e r s m e t bedetermined. The t h i c k n e s s of pavement required over the subgrade and sub-base and the minimum b a s e c o u r s e requirements must be compared w i t h t h e e x i s t i n g pavement t o d e t e r m i n e the overlay requirements.

b)Adjustments tothevariouslayersoftheexisting pavement may be necessarytocompletethedesign.Bituminoussurfacing may have t o be converted t o b a s e , a n d b a s e t o s u b - b a s e c o n v e r s i o n may be r e q u i r e d . A h i g h - q u a l i t ym a t e r i a l may b ec o n v e r t e dt o a lowerA material may n o t q u a l i t y material, such as s u r f a c i n g t o b a s e . beconvertedto a h i g h e r q u a l i t y material. For example,excess sub-basecannotbeconverted t o base. The e q u i v a l e n c yf a c t o r s shown i n T a b l e s 4-9 and 4-10 may be used as guidance i n t h e conversion of l a y e r s . It must berecognized that t h e v a l u e s shown are f o r new materials and the assl.gnment of factors for e x i s t i n g pavements must be based on judgement and experience. Surfacecracking,highdegreeofoxidatton,evidence of l o w s t a b i l i t y , etc., are only a few of t h e c o n s i d e r a t i o n s w h i c h would t e n dt or e d u c et h ee q u i v a l e n c yf a c t o r . Any bituminouslayer located between granular courses in the exLstinp; pavement should beevaluatedinchforinch as g r a n u l a r base o r sub-base course.

c)

To i l l u s t r a t e t h e p r o c e d u r e of d e s i g n i n g a bituminousoverlay, assune an existing taxiway pavement composed of t h e f o l l o w i n g s e c t i o n . The subgrade CBR i s 7 , t h eb i t u m i n o u ss u r f a c ec o u r s e is 4 i n (10 cm) t h i c k , t h e b a s e c o u r s e is 6 i n (15 cm) t h i c k , t h e sub-base is 10 i n (25 cm) t h i c k , andthesub-base CBR i s L5. F r o s ta c t i o n is n e g l i g i b l e . Assume t h e e x i s t i n g pavement is t o a d u a l wheel a i r c r a f t w e i g h i n g be strengthened to accomdate 100 000 l b (45 000 kg)and a n a n n u a l d e p a r t u r e level. of 3 090. The f l e x i b l e pavement r e q u i r e d f o r t h e s e c o n d i t i o n s is: Bituminous surface Base Sub-base T o t a l pavement t h i c k n e s s

4 i n (10 cm) 9 i n ( 2 3 cm) 10 i n (25 cm) 2 3 i n (58 cm)

I C A O 9357 P A R T * 3

c

Part 3 . - Pavements

**

-

4 8 4 1 4 3 b 0019562 4 6 6

3-187

The total pavement thickness must 23 be in ( 5 8 cm) in order to protect the CBR 7 subgrade. The combined thickness of surfacing and base must be 13 in ( 3 3 cm) to protect the CBR 15 sub-base. The existing pavement is thus 3 in ( 7 . 5 cm) aeficient in total pavement thickness, all of which is due to base course. For the sake of illustration, assume the existing bituminous surface is in such a condition that surfacing can be substituted for base at an equivalency ratio of1.3 to 1. Converting 2 . 5 in ( 6 cm) o f surfacing to base yields a base course thickness 9 . 2 in of ( 2 3 cm) leaving 1 . 5 in ( 4 cm) of unconverted surfacing. A 2.5 In ( 6 cm) overlay would be required to achieve 4 in a (10 cm) thick surface. In this instance the minimum 3 in ( 7 . 5 cm) overlay thickness would control.A 3 in ( 7 . 5 cm) overlay thickness would be required.

d)

The most difficult part of designing bituminous overlays for flexible pavements is the determination ofCBR the values for the subgrade and sub-base and conversion of layers. Subgrade and sub-baseCBR values can best be determined by conducting field in-place CBR tests. The subgrade and sub-base must be at the equilibrium moisture content when field CBR tests are conducted. Normally a pavement which has been in place for 3atyears least will be in equilibrium. Layer conversions, i.e., converting base of engineering judgement. to sub-base, etc., are largely a matter When performing the conversions, it is recommended that any converted thicknesses never be rounded off.

4.4.26.5

Bituminous overlay on exis.ting rigzd pavement. To establish the required thickness of bituminous overlay for an existing rigid pavement, it is first necessary to determine the single thickness of rigid pavement required to satisfy the design conditions. This thickness is then modified by a factor F which controls the degree of cracking which will occur in the existing rigid pavement. The effective thickness of the existing rigid pavement is also adjusted by a conditioncb.factor The F andCb factors perform two different-functions in the bituminous overlay determination as discussed below: a)

The factor F which controls the degree of cracking which will occur in the base pavement is a function of the amount of traffic and the subgrade strength. The F factor selected will dictate the final condition of the overlay and base pavement. The F factor in effect is indicating that the entire concrete single slab thickness determined from the design curves is not needed because a bituminous overlay pavement is allowed to crack and deflect more than a conventional rigid pavement. More cracking and deflection is allowable as the bituminous surfacing will not spa11 and can conform to greater deflection than a totally rigid pavement. Photographs of various overlay and F base pavementsshown in Figure4-63 illustrate the roeaning of the factor. Figures 4-63 a), b ) and c) show how the overlay and base pavements fail as more traffic is applied to a bituminous onoverlay an existing rigid pavement. In the design of a bituminous overlay,

I C A O 9L57 P A R T 8 3

**

D q6L154Lb OOL95b3 3T2

3-188 the conditionof the overlay and base pavement after the design life should be close to that shown in Figure4-63 b). Figure 4-64 is a graph enabling the designer to select the appropriate F value to 4-63 b). yield a final condition close to that shown in Figure b)

The condition factor Cg applies tu the existing rigid pavement. The cb factor is an assessmentof the structural integrity of the existing pavement. The determination of the proper Cg value is a judgement decision for which only general guidelines can be provided. A cb value of 1.0 should be used when the existing slabs contain nominal initial cracking and 0.75 when the slabs contain multiple cracking. The designer is cautioned that the range of ch values used in bituminous overlay designs is different from the Cr values used in rigid overlay pavement design. The minimum Cb value is 0.75. A single cb should be established f o r an entire area. The Cb value should not be varied along a pavement feature.

c) After the F factor, condition factor cb, and single thickness of rigid pavement have been established, the thickness of the bituminous from the following formula: overlay is computed t

where t = thickness of bituminous overlay, inches ich controls the degree of cracking F = factor wh in the base pavement h = single thicknessof rigid pavement required for design conditions, inches. Use the exact value of h; do not round off. from to 0.75 cb = condition factor for base pavement ranging 1.0 he = thickness of existing rigid pavement, inches Calculation of bituminous overlay thickness in metric units should be performed using the formula below: t = 2.5

where t is i n centimetres h is in centimetres h, is in centimatres

I C A O 9357 P A R T * 3 * t

4 8 4 3 4 3 b 0039564 2 3 9

=

Part 3 . - P a v e m e n t s

3-189

SURFACE O F OVERLAY

BASE PAVEMENT

(a>

F i g u r e 4-63.

SURFACE O F OVERT.,AY

BASE PAVEMF,PJT

SURFACE OF OVERLAY

BASEPAVEMENT

I l l u s t r a t i o n of v a r i o u s F f a c t o r s f o r b i t u m i n o u s overlay design

MODULUS OF

SUBGRADE

REACTION

pc i 100

20 0

300

400

Figure 4 - 6 4 . Graph of F factors v s . modulus of subgrade reaction for different traffic levels

I C A O 9 3 5 7 P A R T * 3 tt

=

4BYL43b 0 0 3 9 5 b b 003

Part 3 . - Pavements d)

3-191

The designof a bituminous overlay for a rigid pavement which has an existing bituminous overlay is slightly different. The designer should treat the problem as if the existing bituminous overlay were not present, calculate the overlay thickness required, and then adjust the calculated thickness to compensate for the existing overlay. If this procedure is not used, inconsistent results will often be produced. 1) An example of the procedure follows. Assume an existing pavement consists of a 10 in (25 cm) rigid pavement with a 3 in (7.5 em) bituminous overlay. The existing pavement is to be strengthened to be equivalent to a single rigid pavement thickness of1 4 in ( 3 6 cm). Assume anF factor of0.9 and Cb of 0.9 are appropriate for the existing conditions. 2)

Calculate the required thickness of bituminous overlay as if the existing3 in (7.5 cm) overlay were not present. t = 2.5 ( 0 . 9

X

14

-

0.9 X 10)

t = 9 in (23 cm) 3)

An allowance is then made for. the existing bituminous overlay. In this example assume the existing overlay is in such a condition that its effective thickness is2.5only in (6 cm). The required overlay thickness would then 9 - be 2.5 = 6.5 in (17 cm). The determination of the effective thickness of the existing overlay is a matter of engineering judgement.

e) The formula for calculating the thickness of bituminous overlays on rigid pavements is limited in application to overlay thicknesses which are equal to or less than the thickness of the base rigid pavement. If the overlay thickness exceeds the thickness of the base pavement, the designer should consider designing the overlay as a flexible pavement and treating the existing rigid pavement as a high-quality base material. This limitation is based on the fact that the formula assumes the existing rigid pavement will support considerable load by flexural action. However, the flexural contribution becomes negligible for thick bituminous overlays. 4.4.26.6

Design of concrete overlays. Concrete overlays can be constructed on existing rigid or flexible pavements. The minimum allowable thickness for concrete overlays is5 in (13 cm) when placed on a flexible pavement, directly on a rigid pavemen or on a levelling course. The minimum thickness of a concrete overlay which is bonded to an existing rigid pavement 3isin (7.5 cm2. The design of concrete overlays is predicated on equating the base and overlay section to a single slab thickness. The formulas presented were developed from research on test track pavements and observations of in-service pavements.

3-192

Aerodrome Desiw Manual

4.4.26.7 C o n c r e t eo v e r h yo n flcxtblc pavement. The d e s i g n of concreteoverlayson e x i s t i n p ; f l e x i b l e pavements is basedonthedesigncurves in 4.4.18. The e x i s t i n g f l e x i b l e pavement is considered a f o u n d a t i o n f o r - t h e o v e r l a y s l a b . a)

Fordesign of t h e r i g i d pavement, t h e e x i s t i n g f l e x i b l e pavement s h a l l b e a s s i g n e d a k v a l u e u s i n g F i g u r e 4-35 o r 4-55 o r by conducting a p l a t e b e a r i n g test on t h e e x i s t i n g f l e x i b l e pavement. I n e i t h e r case t h e k value assigned should not exceed 500.

b)

When f r o s t c o n d i t i o n 6 r e q u i r e a d d i t i o n a l t h i c k n e s s , t h e u s e o f n o n - s t a b i l i z e d material is not allowed as t h i s would r e s u l t i n a sandwichpavement. The f r o s t p r o t e c t f o n mst beprovidedby s t a b i l i z e d material.

Concrete overlay on rigid pavement. The d e s i g nocf o n c r e t eo v e r l a y s on e x i s t i n g r i g i d pavements i s a l s o p r e d i c a t e d o n t h e r i g i d pavementdesigncurves. The r i g i d pavem-t design curves i n d i c a t e t h e t h i c k n e s s o f c o n c r e t e r e q u i r e d to satisfy the d e s i g nc o n d i t i o n sf o r a s i n g l e t h i c k n e s s of concretepavement. Use o f t h i s method requiresthedesignertoassign a k valuetotheexistingfoundation. The k v a l u e may be determined by field bearing tests conducted i n test p i t s c u t t h r o u g h t h e e x i s t i n g r i g i d pavement, o r may b e e s t i m a t e d f r o m c o n s t r u c t i o n r e c o r d s f o r t h e e x i s t i n g pavement. The d e s i g n o f a c o n c r e t e o v e r l a y o n a r i g i d pavement r e q u i r e s a n a s s e s s m e n t o f t h e s t r u c t u r a l integrityoftheexistingrigid pavement. The c o n d i t i o n f a c t o r s h o u l d b e s e l e c t e d a f t e r a pavement conditionsurvey. The s e l e c t i o n of a c o n d i t i o n f a c t o r i s a matter of e n g i n e e r i n gj u d g e m e n t The use of n o n - d e s t r u c t i v e t e s t i n g (HDT) c a n be o f c o n s i d e r a b l e v a l u e in a s s e s s i n g t h e c o n d i t i o n of an e x i s t i n g pavement. NDT c a n a l s o be used t o determine sites for t e s t p i t s . In o r d e r t o p r o v i d e a more uniformassessmentofcondition f a c t o r s , t h e f o l l o w i n g v a l u e s are defined:

4.4.26.8

C r = 1.0 f o r e x i s t i n g pavement i n good c o n d i t i o n

cracking evident but

-

sane

minor

no s t r u c t u r a l d e f e c t s .

Cr = 0.75 f o r e x i s t i n g pavement c o n t a i n i n g i n i t i a l c o r n e r c r a c k s t o l o a d i n g b u t n o p r o g r e s s i v e c r a c k i n g or j o i n t f a u l t i n g . C r = 0.35 f o r e x i s t i n g pavement i n p o o r s t r u c t u r a l c o n d i t i o n cracked or crushed and faulted joints.

due

- badly

The t h r e e c o n d i t i o n s d i s c u s s e d a b o v e are used t o i l l u s t r a t e t h e c o n d i t i o n at factorratherthanestablishtheonlyvaluesavailabletothedesigner.Conditions a p a r t i c u l a r l o c a t i o n may r e q u i r e t h e u s e o f a n i n t e r m e d i a t e v a l u e of C, w i t h i n t h e recommended range.

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P a r t 3 . - Pavements a )C o n c r e t eo v e r l a yw i t h o u tl e v e l l i n gc o u r s e . The t h i c k n e s so ft h e concrete overlay slab applied directly over the existing rigid pavement i s computedby t h e f o l l o w i n g f o r m u l a :

hc = r e q u i r e d t h i c k n e s s o f c o n c r e t e o v e r l a y h

= r e q u i r e ds i n g l es l a bt h i c k n e s sd e t e r m i n e df r o md e s i g nc u r v e s

he = thickness of existing rigid

pavement

Cr = c o n d i t i o n f a c t o r

Due t o t h e i n c o n v e n i e n t e x p o n e n t s i n t h e a b o v e f o r m u l a , g r a p h i c d i s p l a y s are g i v e n i n F i g u r e s 4-65 and 4-66. These of t h e s o l u t i o n o f t h e f o r m u l a graphs w e r e prepared for only two d i f f e r e n t c o n d i t i o n f a c t o r s , C r = 1.0 and 0.75. The useof a c o n c r e t e o v e r l a y p a v e m e n t d i r e c t l y o n a n e x i s t i n g r i g i d pavement w i t h a c o n d i t i o n f a c t o r o f less t h a n 0.75 is n o t recommended b e c a u s e of t h e l i k e l i h o o d o f r e f l e c t i o n c r a c k i n g . b )C o n c r e t eo v e r l a yw i t hl e v e l l i n gc o u r s e .I n some i n s t a n c e s it may b e necessary to apply a levelling course of bituminous concrete to an e x i s t i n g r i g i d pavement p r i o r t o t h e a p p l i c a t i o n o f t h e c o n c r e t e o v e r l a y . Under t h e s ec o n d i t i o n s a d i f f e r e n tf o r m u l af o rt h e c o m p u t a t i o no ft h eo v e r l a yt h i c k n e s s i s r e q u i r e d . When t h e e x i s t i n g pavementand overlaypavement are s e p a r a t e d , t h e s l a b s act more i n d e p e n d e n t l y t h a n when t h e s l a b s are i n c o n t a c t w i t h e a c h o t h e r . The f o r m u l a f o r t h e t h i c k n e s s o f a n o v e r l a y s l a b when a l e v e l l i n g c o u r s e i s used is as f o l l o w s : hc =

1

h2

-

Crhe2

hc = r e q u i r e d t h i c k n e s s of c o n c r e t e o v e r l a y h

= r e q u i r e ds i n g l es l a bt h i c k n e s sd e t e r m i n e df r o md e s i g nc u r v e s

he = t h i c k n e s s o f e x i s t i n g r i g i d

pavement

C r = condition factor

The l e v e l l i n g c o u r s e m u s t b e c o n s t r u c t e d o f h i g h l y s t a b l e b i t u m i n o u s c o n c r e t e . A g r a n u l a rs e p a r a t i o nc o u r s e is n o ta l l o w e d as t h i s would c o n s t i t u t es a n d w i c hc o n s t r u c t i o n .G r a p h i cs o l u t i o n so ft h ea b o v e e q u a t i o n are shown i n F i g u r e s 4-67 and 4-68. Thesegraphs were p r e p a r e df o rc o n d i t i o nf a c t o r so f 0.75 and 0.35. O t h e rc o n d i t i o n f a c t o r s betweenthesevaluescannormallybe computed t o s u f f i c i e n t a c c u r a c y by i n t e r p o l a t i o n .

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Aerodrome Design Manual c)

Bonded concrete overlays. Concreteoverlays which are bonded t o e x i s t i n g r i g i d pavements are sometimes usedunder c e r t a i n c o n d i t i o n s . By bonding t h e c o n c r e t e o v e r l a y t o t h e e x i s t i n g r i g i d pavement t h e new s e c t i o n behaves as a monolithicslab. The thickness of bonded overlay required i s computed by s u b t r a c t i n g t h e t h i c k n e s s of t h e e x i s t i n g pavement from t h e t h i c k n e s s of the required alab thickness determined from design curves.

where :

hc = requfred thickness of concrete overlay h

= required single elab thicknees determined

he = t h i c k n e s s o f e X i 8 t h g r i g i d

from design curves

pavement

only when t h e e x i s t i n g r i g i d pavement Bonded overlays should be used i s i n good condition.Defects in the e x i s t i n g pavement are more l i k e l y t o r e f l e c t t h r o u g h a bonded overlay than other types of concreteoverlays. The major problem l i k e l y t o b e e n c o u n t e r e d with bonded concreteoverlays is achievingadequate bond. Elaborate eurface preparation and exacting construction techniques are required to enaure bond.

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Pavement e v a l u a t i o n

4.4.27.1 Purposes of

pavement e v a l u a t i o n a )A i r p o r p t avements are e v a l u a t e df o rs e v e r a lr e a s o n s .E v a l u a t i o n s are needed t o e s t a b l i s h l o a d c a r r y i n g c a p a c i t y f o r e x p e c t e d pavements t o s u p p o r t s i g n i f i c a n t o p e r a t i o n s , t o assess t h e a b i l i t y o f changesfromexpectedvolumes or types of traffic, and t o d e t e r m i n e the condition of existing. pavements for use in the planning or a facility. d e s i g n of improvementswhich may b e r e q u i r e d t o u p g r a d e

are e s s e n t i a l l y t h e reversal ofdesignproceb )E v a l u a t i o np r o c e d u r e s Manual d u r e s .S i n c et h e new FAA d e s i g nm e t h o d o l o g yd e s c r i b e di nt h i s may r e s u l t i n s l i g h t l y d i f f e r e n t t h i c k n e s s e s t h a n o t h e r d e s i g n methods it would b e i n a p p r o p r i a t e t o e v a l u a t e e x i s t i n g p a v e m e n t s b y t h e new method u n l e s s t h e y had a l s o b e e n d e s i g n e d b y t h a t m e t h o d . This could reduce allowable loads and penalize aircraft operators. To a v o i d t h i s s i t u a t i o n , p a v e m e n t ss h o u l db ee v a l u a t e df o rt h e variousconditionsindicatedinthefollowingparagraphs. 4 . 4 . 2 7 .E 2 v a l u a t i o nfsoerx p e c t eodp e r a t i o n s . When a i r p o r t pavements are s u b j e c t e d totheloadswhich w e r e a n t i c i p a t e d a t t h e time of d e s i g n , t h e i r e v a l u a t i o n s h o u l d b e b a s e d on t h a t o r i g i n a l d e s i g n method.Forexample, i f a pavement w a s designedby method X t o serve certain a i r c r a f t f o r a 20-year l i f e a n d t h e t r a f f i c u s i n g t h e pavement i s e s s e n t i a l l y t h e same as w a s a n t i c i p a t e d a t t h e time o f d e s i g n , t h e pavement s h o u l d b e e v a l u a t e da c c o r d i n gt o method X. The e v a l u a t o rs h o u l dr e c o g n i z et h a t some d e t e r i o r a t i o n w i l l o c c u ro v e rt h e 20 y e a rd e s i g n l i f e . The l o a d b e a r i n g s t r e n g t h o f t h e pavement The p r i o r s h o u l d not bereduced i f t h e pavement i s p r o v i d i n g a s a f e o p e r a t i o n a l s u r f a c e . e v a l u a t i o n c u r v e s are f u r n i s h e d i n Appendix4, t o f a c i l i t a t e t h i . s e v a l u a t i o n p o l i c y . S e e F i g u r e s A4-8 to A4-21. 4 . 4 . 2 7 .E 3 v a l u a t i o nfsocrh a n g i ntgr a f f i cE. v a l u a t i o n s are s o m e t i m erse q u i r etdo determine the ability of an existing pavement t o s u p p o r t s u b s t a n t i a l c h a n g e s i n pavement l o a d i n g s .T h i sc a nb eb r o u g h to nb yt h ei n t r o d u c t i o no fd i f f e r e n tt y p e so fa i r c r a f to r it is a l s o reconmended t h a t e x i s t i n g changes i n t r a f f i c volume. I n t h e s e i n s t a n c e s w e r e d e s i g n e d . The e f f e c t p a v e m e n t sb ee v a l u a t e da c c o r d i n gt ot h em e t h o d sb yw h i c ht h e y of c h a n g e s i n t r a f f i c volume are u s u a l l y small and w i l l n o t h a v e a l a r g e i m p a c t o n a l l o w a b l el o a d s . The e f f e c t o f c h a n g e s i n a i r c r a f t t y p e s d e p e n d s on t h eg e a rw e i g h t asd g e a rc o n f i g u r a t i o n of t h e a i r c r a f t . The l o a d c a r r y i n g c a p a c i t y o f e x i s t i n g b r i d g e s , culverts,stormdrains, and o t h e r s t r u c t u r e s s h o u l d a l s o b e c o n s i d e r e d i n t h e s e e v a l u a tions.

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4.4.27.4 . EvaLuationsforplanninn,anddesigr,.Evalnations o f e x i s t i n g pavements t o be used in planning or designing improvements should be based on t h e mrthndwhich will beusedtodesignthoseimprovements. The procedures t o b 2 followed i n evaluating pavements according t o t h e d e s i g n c r i t e r i a contained i n t h i s Xanual are as follows:

aE) v a l u a t i o n

b)

steps

1)

S i t ei n s p e c t i o n . This may i n c l u d e ,i na d d i t i o n to theexamination of t h e e x i s t i n g d r a i n a g e c o n d i t i o n s a n d d r a i n a g e f a c L l i t i e s o f area, o u t f a l l , water t a b l e , t h e site, c o n s i d e r a t i o n o f t h e d r a i n a g e areadevelopment, etc. Evidence of f r o s ta c t i o ns h o u l db e ob served.

2)

Recordsresearchandevaluation. Tnis s t e p may, a t Least i n p a r t ,p r e c e d e s t e p 1) above. This s t e p i s accomplished by a thorough review o f c o n s t r u c t i o n d a t a a n d h i s t o r y , d e s i g n considerations,specifications,testing methodsand r e s u l t s , as-builtdrawings,andmaintenancehistory.Peatherrecords and t h e mostcomplete t r a f f i c h i s t o r y a v a i l a b l e are a l s o p a r t s of a u s a b l er e c o r d sf i l e . When s o i l ,m o i s t u r e , andweather conditionsconducivetodetrimentalfrostactionexist,an nay b e r e q u i r e d . adjustment to the evaluation

3)

Sampling a n dt e s t i n g .

Tne need for andscope of pfiysical tests and materials a n a l y s e s s i l l be based on t h e f i n d i n g s and typeof made fromthe s i t e i n s p e c t i o n , r e c o r d s r e s e a r c h , e v a l u a t i o n . A c o m p l e t ee v a l u a t i o nf o rd e t a i l e dd e s i g n will r e q u i r e more samplingandtestingthan,€orexample,an e v a l u a t i o ni n t e n d e d for u s e i n a master plan.Samplingand on t h e t h i c k n e s s , t e s t i n g is intendedtoprovideinformation qualityandgeneralcondition of t h e pavement elements.

4)

E v a l u a t i o nr e p o r t . Analysis af s t e p s 11, 2 ) and 3) should culminateintheassignmentofloadcarryingcapacity to the pavement s e c t i o n su n d e rc o n s i d e r a t i o n . The a n a l y s e s ,f i n d i n g s , and test r e s u l t s s h o u l d b e i n c o r p o r a t e d i n a permanent record f o r f u t u r er e f e r e n c e .w h i l et h e s en e e dn o tb ei na n y p a r t i c u l a r form, i t i s recommended t h a t a d r a w i n g i d e n t i f y i n g area limits of s p e c i f i c pavement s e c t i o n s b e i n c l u d e d .

Direct samplingprocedures. The b a s i ce v a l u a t i o np r o c e d u r ef o r planning and design w i l l b e v i s u a l i n s p e c t i o n and reference t o t h e FAA d e s i g n c r i t e r i a , supplemented by the additional sampling, t e s t i n g , and r e s e a r c h which t h e e v a l u a t i o n p r o c e s s e s may warrant. wear o r stress, For r e l a t i v e l y new pavement w i t h o u t v i s i b l e s i g n s o f s t r e n g t h may be based on i n s p e c t i o n o f t h e a s - c o n s t r u c t e d s e c t i o n s , w i t h m o d i f i c a t i o n f o r a n y material v a r i a t i o n s o r d e f i c i e n c i e s of record. Where a g e o r v i s i b l e d i s t r e s s i n d i c a t e s t h e o r i g i n a l s t r e n g t h no l o n g e r exists, f u r t h e r m o d i f i c a t i o n s h o u l d b e a p p l i e d on t h e b a s i s of judgement o r a combination of judgement and

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Part 3.- Pavements

supplemental physical testing. For pavements which consist of sections not readily comparable to FAA design standards, evalcration should be based on FAA standards after materials comparison and equivalencies have been applied.

1) Flexible pavements. Laboratory or field CBR tests may be useful in supplementing soil classification tests. Figure 4-69 shows the approximate relationship between the subgrade classification formerly used by FAA the and CBR.

I

CB R 3

4

5

I

6

7

8

9

11

1

3

1

6

2

0

SUBGRADE CLASS

Figure 4-69.

CBR - FAA subgrade class comparisons

Conversion of F subgrade classification factors to CBR is permissible where CBR tests are not feasible. The thickness o f the various layers in the flexible pavement structure must be known in order to evaluate the pavement. Thickness may be determined from borings or test pits. As-built drawings and records can also be used to determine thicknesses if the records are sufficiently complete and accurate.

2)

Rigid pavements. The evaluation requires the determinationof the thicknessof the component layers, the flexural strength of the concrete, and the modulus of subgrade reaction. a)

The thickness of the component layersis usually available from construction records. Where information is not available or of questionable accuracy, thicknesses may be determined by borings or test pits in the pavement.

b)

The flexural strength of the concrete is most accurately determined from test beams sawed from the existing pavement and tested in accordance with ASTM C-78. Sawed beams are expensive to obtain and costs incurred in obtaining sufficient numbers of beams to establish a representative sample may be prohibitive. Construction records maybe used as a source of concrete flexural strength data, if available. The construction data will probably have to be adjusted for age as concrete strength increases with time.An approximate relationship between concrete compressive strength and

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~~~~

~

~~

~

~~~

~~~

~~~~~

~

flexural strength exists and can be formula :

R = 9 where R fc'

=

computedby

the following

p

f l e x u r a ls t r e n g t h

= compressive strength

T e n s i l e s p l i t t i n g tests (ATSH C-496) c a n b e u s e d t o d e t e r m i n e a n a p p r o x i m a t i v ev a l u eo ff l e x u r a ls t r e n g t h .T e n s i l es p l i t t i n gs t r e n g t h should be multiplied by a b o u t 1 . 5 t o a p p r o x i m a t e t h e f l e x u r a l s t r e n g t h . It s h o u l d b e p o i n t e d o u t t h a t t h e r e l a t i o n s h i p s b e t w e e n f l e x u r a l are strength and compressive strength or tensile splitting strength approximate and considerable variations are l i k e l y . c)

i s determined by p l a t e b e a r i n g tests The modulusofsubgradereaction performed on thesubgrade. These tests shouldbe made inaccordance w i t h the p r o c e d u r e s e s t a b l i s h e d i n AASHTO T 222. An i m p o r t a n t p a r t modulus o f t h e test p r o c e d u r e f o r d e t e r m i n i n g t h e s u b g r a d e r e a c t i o n is t h e c o r r e c t i o n f o r s o i l s a t u r a t i o n which is c o n t a i n e d i n t h e p r e s c r i b e ds t a n d a r d . The n o r m a la p p l l c a t i o nu t i l i z e s a correction factor determined by t h e c o n s o l i d a t i o n t e s t i n g o f s a m p l e s a t -in situ and s a t u r a t e dm o i s t u r ec o n t e n t .F o re v a l u a t i o n of o l d e r pavement, whereevidence exists t h a t t h e s u b g r a d e m o i s t u r e h a s s t a b i l i z e d o r varies through a limited range, the correction for saturation is n o t necessary. If a f i e l d p l a t e b e a r i n g test i s n o t p r a c t i c a l , t h e modulus of s u b g r a d e r e a c t i o n may be estimated by using Table 4-8.

d)

modulus of s u b g r a d e r e a c t i o n . Sub-bases w i l l r e q u i r e a n a d j u s t m e n t t o t h e is r e q u i r e d t o c a l c u l a t e a k v a l u e f o r a The thickness of the sub-base sub-base. The sub-basethicknesscan be determinedfromconstruction r e c o r d s o r fromborings. The guidancecontainedin4.4.19shouldbe used i n a s s i g n i n g a k v a l u e t o a sub-base.

4.4.27.5 Flexiblepavements.After a l l of t h e v a l u a t i o np a r a m e t e r o s tfh e x i s t i n g f l e x i b l e pavement h a v e b e e n e s t a b l i s h e d u s i n g t h e g u i d a n c e g i v e n i n t h e a b o v e p a r a g r a p h s , t h e e v a l u a t i o n p r o c e s s is e s s e n t i a l l y t h e reverse o f t h e d e s i g n p r o c e d u r e . The d e s i g n c u r v e s are used to determine the load carrying capacity of the existing pavement. Required inputs are subgrade andsub-base CBR v a l u e s , t h i c k n e s s e s o f s u r f a c i n g , b a s e annual departurelevel.Severalchecksmustbeperformed andsub-basecoursesandan of a f l e x i b l e pavement. The c a l c u l a t i o n w h i c h todeterminetheloadcarryingcapacity y i e l d s t h e lowest a l l o w a b l e l o a d w i l l c o n t r o l t h e e v a l u a t i o n .

a )T o t a l pavement t h i c k n e s s .E n t e rt h el o w e ra b s c i s s a of t h ea p p r o p r i a t e d e s i g n c u r v e w i t h t h e t o t a l pavement thickness of t h e e x i s t i n g pavement. Make a v e r t i c a l p r o j e c t i o n t o t h e annual d e p a r t u r e level l i n e . A t t h e p o i n t of i n t e r s e c t i o n b e t w e e n t h e v e r t i c a l projection a n d t h e d e p a r t u r e level line make a h o r i z o n t a l p r o j e c t i o n a c r o s s t h e d e s i g n c u r v e . Enter theupperabscissawiththe CBR v a h e of the subgrade. Make a v e r t i c a l p r o j e c t i o n downward u n t i l i t i n t e r s e c t s t h e h o r i z o n t a l

I C A O 7157 PARTS3 t t

P a r t 3 . - Pavements

4841416 0 0 3 9 5 7 8 8 2 3

= 3-203

p r o j e c t i o n made previously. The point of i n t e r s e c t i o n of t h e s e two p r o j e c t i o n s w i l l be i n t h e v i c i n i t y of t h e l o a d l i n e s on t h e d e s i g n curves. An allowableload i s read by n o t i n g where t h e i n t e r s e c t i o n point falls in relation to be load lines. b)Thickness of s u r f a c i n g and base. The combined thickness of s u r f a c i n g and base must a l s o h e checked t o e s t a b l i s h t h e l o a d c a r r y i n g c a p a c i t y of a n e x i s t i n g f l e x i b l e pavement. T h i s c a l c u l a t i o n r e q u i r e s t h e CBR of the sub-base, the combined thickness of s u r f a c i n g andbase and t h e a n n u a ld e p a r t u r el e v e l as i n p u t s . The procedure i s t h e same as t h a t described in a) above, except that the sub-base CBR and combined thickness of s u r f a c i n g and base are used t o e n t e r t h e d e s i g n c u r v e s .

c)

Deficiencyinbasecoursethickness. The t h i c k n e s s of t h ee x i s t i n g base course should be compared w i t h t h e minimum base course thicknesses shown i n Figure 4-45. I n p u t sf o ru s e of t h i s c u r v e are t o t a l pavement thicknessandsubgrade CBR. E n t e r t h e l e f t o r d i n a t e of Figure 4-45 withthetotal pavement thickness. Make a h o r i z o n t a l p r o j e c t i o n t o CBR l i n e . A t t h e p o i n t o f i n t e r s e c t i o n o f theappropriatesubgrade t h e h o r i z o n t a l p r o j e c t i o n and the subgrade CBR l i n e , make a v e r t i c a l p r o j e c t i o n down t o t h e lower a b s c i s s a and r e a d t h e minimum base c o u r s et h i c k n e s s .N o t i c et h a tt h e minimum basecoursethickness is 6 i n (15 cm). I f t h e r e i s a d e f i c i e n c yi nt h et h i c k n e s s of t h e existing base course, the pavement should be closely monitored for s i g n s of d i s t r e s s . The formulation of p l a n sf o ro v e r l a y i n gt h e pavement tocorrectthedeficiencyshould beconsidered.

d)Deficiencyinsurfacingthickness. The t h i c k n e s s of t h ee x i s t i n g surface course should be compared w i t h t h a t shown on t h e a p p r o p r i a t e is t h i n n e r t h a n t h a t designcurve. I ft h ee x i s t i n gs u r f a c ec o u r s e given on t h e d e s i g n c u r v e , t h e pavement should be closely observed far surfacefailures. It is recommended t h a t p l a n n i n g t o c o r r e c t t h e d e f i c i e n c y i n surfacing thickness be considered.

4.4.27.6 Rigid pavements. The e v a l u a t i o n of r i g i d pavements f o a r i r c r a f rt e q u i r e s concreteflexuralstrength, k v a l u e of t h e f o u n d a t i o n , s l a b t h i c k n e s s , and annual d e p a r t u r e l e v e l as i n p u t s . The r i g i d pavement designcurves are used t o e s t a b l i s h l o a d carrying capacity. The designcurves are entered on t h e l e f t o r d i n a t e w i t h t h e f l e x u r a l s t r e n g t h of t h e c o n c r e t e . A h o r i z o n t a l p r o j e c t i o n i s made t o t h e k v a l u e o f t h e foundation. A t t h e p o i n t o f i n t e r s e c t i o n o f t h e h o r i z o n t a l p r o j e c t i o n and t h e k l i n e , a v e r t i c a l p r o j e c t i o n i s made i n t o t h e v i c i n i t y o f t h e l o a d l i n e s . The s l a b t h i c k n e s s i s entered on t h e a p p r o p r i a t e d e p a r t u r e l e v e l s c a l e on t h e r i g h t s i d e of t h e c h a r t . A h o r i z o n t a l p r o j e c t i o n i s made from t h e t h i c k n e s s scale u n t i l i t i n t e r s e c t s t h e p r e v i o u s vertical projection. The p o i n t o f i n t e r s e c t i o n o f t h e s e p r o j e c t i o n s w i l l be in the vicinity of the load lines. The load carrying capacity i s read by n o t i n g where t h e intersection point falls in r e l a t i o n t o t h e l o a d l i n e s .

CHAPTER 5 .

5.1

-

METHODS FOR IMPROVING RUNWAY SURFACE TEXTURE

Purpose

5.1.1 Annex 1 4r e q u i r e tsh atth es u r f a c eo f a paved runway be so c o n s t r u c t e d as t o p r o v i d e good f r i c t i o n c h a r a c t e r i s t i c s when t h e runway i s wet. A d d i t i o n a l p r o v i s i o n s c o n t a i n minimum s p e c i f i c a t i o n s f o r t h e c o n f i g u r a t i o n o f runway s u r f a c e s a n d r e c o g n i z e in particular the need for some f o r m o f s p e c i a l s u r f a c e t r e a t m e n t . The purpose of t h i s c h a p t e r i s to provide guidance on proved methods for improving runway s u r f a c e t e x t u r e . This includes essential engineering criteria for the design, construction and treatment of runway s u r f a c e s , t h e u n i f o r m a n d w o r l d w i d e a p p l i c a t i o n o f w h i c h i s considered important to satisfy the relevant provisions of Annex 14. 5.2 5.2.1

Basic Considerations

H i s t o r i c a l background

5.2.1.1 With t h es t e a d yg r o w t h of a i r c r a f t mass a n dt h ea s s o c i a t e ds i g n i f i c a n t increase in the takeoff and landing speeds, a number o f o p e r a t i o n a l p r o b l e m h a v e of runway s u r f a c e s . One o ft h e most s i g n i f i c a n t become a p p a r e n tw i t hc o n v e n t i o n a lt y p e s and potentially dangerous is t h e a q u a p l a n i n g phenomenon which has been held responsible i n a nmber of aircraft incidents and accidents. 5.2.1.2 E f f o r t st oa l l e v i a t et h ea q u a p l a n i n gp r o b l e mh a v er e s u l t e di n t h e development of new types of runwaypavements o f p a r t i c u l a r s u r f a c e t e x t u r e a n d o f improved d r a i n a g ec h a r a c t e r i s t i c s .E x p e r i e n c eh a s shown t h a t t h e s e f o r m of s u r f a c e f i n i s h , apart from successfully reinhizing aquaplaning risks, provide a 8ubstantially higher f r i c t i o n l e v e l i n a l l degreesofwetness, i.e. from damp t o a f l o o d e d s u r f a c e . 5.2.1.3 It is now g e n e r a l l ya g r e e dt h am t e a s u r i n ga n dr e p o r t i n g wet f r i c t i o n conditions i s notrequiredtobedoneon a dailyroutinebasis. This is t h e r e s u l t of t h e development of a new philosophy of dealing with the w e t runway problem.There i s of c o u r s e a need f o r a g e n e r a l i n p r o v e m e n t o f t h e f r i c t i o n l e v e l s p r o v i d e d by runvay s u r f a c e s i n "normal" w e t c o n d i t i o n s a n d for t h e e l i d n a t i o n of s u b s t a n d a r d s u r f a c e s i n particular. 5.2.1.4 T h i hs a rse s u l t e d i n t h ed e f i n i t i o n of anirnumacceptable wet f r i c t i o n l e v e l s f o r new a n d e x i s t i n g runways. Accordinglyrunwaysshould be s u b j e c t t o p e r i o d i c e v a l u a t i o n of t h e f r i c t i o n l e v e l by u s i n g t h e t e c h n i q u e s i d e n t i f i e d i n Attachment 8 o f Annex 14andrelateddocuments. This c o n c e p t f a v o u r s t h e a p p l i c a t i o n o f t h e modern technology for the finishing of surfaces which experience has proved effectively p r o v i d e 8 t h e wet friction requirements and mintmizes aquaplaning.

5.2.2

Functional requirements

5.2.2. 1 A runway pavement,considered following three basic functions:

as a whole, i s s u p p o s e dt of u l l i lt h e

3-204

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4 8 4 3 4 3 b 0037580 q B 3 W

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3-205

a)

t op r o v i d ea d e q u a t eb e a r i n gs t r e n g t h ;

b)

t o p r o v i d e good r i d i n g q u a l i t i e s ;

c)

t o p r o v i d e good s u r f a c e f r i c t i o n c h a r a c t e r i s t i c s .

and

The f i r s t c r i t e r i o n a d d r e s s e s t h e s t r u c t u r e of t h e pavement, t h e s e c o n d t h e g e o m e t r i c shape of the top of the pavement and the third the texture of the actual surface.

5.2.2.2 All t h r e e c r i t e r i a are c o n s i d e r e de s s e n t i a tl oa c h i e v e a pavement which w i l l f u n c t i o n a l l ys a t i s f yt h eo p e r a t i o n a lr e q u i r e m e n t s . From t h e o p e r a t i o n a l a s p e c t , however,thethirdone i s consideredthemostimportantbecause i t has a direct impact on t h e s a f e t y o f a i r c r a f t o p e r a t i o n s . R e g u l a r i t y a n d e f f i c i e n c y may a l s o b e a f f e c t e d . Thus t h e f r i c t i o n c r i t e r i o n may become a d e c i s i v e f a c t o r f o r t h e s e l e c t i o n a n d t h e f o r m of t h e most s u i t a b l e f i n i s h o f t h e p-avement s u r f a c e . 5.2.3

Problem i d e n t i f i c a t i o n

5.2.3.1 When i n a d r ya n dc l e a n s t a t e , i n d i v i d u a l runways g e n e r a l l yp r o v i d e comparable f r i c t i o n c h a r a c t e r i s t i c s w i t h o p e r a t i o n a l l y i n s i g n i f i c a n t d i f f e r e n c e s i n f r i c t i o n l e v e l s , r e g a r d l e s s of t h e t y p e of p a v e m e n t ( a s p h a l d c e m e n t c o n c r e t e ) a n d t h e is relatively c o n f i g u r a t i o n of t h e s u r f a c e . Moreover, t h e f r i c t i o n l e v e l a v a i l a b l e u n a f f e c t e d by t h e s p e e d o f t h e a i r c r a f t . Hence, t h e o p e r a t i o n o n d r y runway s u r f a c e s i s s a t i s f a c t o r i l y c o n s i s t e n t a n d no p a r t i c u l a r e n g i n e e r i n g c r i t e r i a f o r s u r f a c e f r i c t i o n are needed f o r t h i s case.

a

5.2.3.2 I n c o n t r a s t , when t h e runway s u r f a c e i s a f f e c t e d by water t o any degree of w e t n e s s (i.e. from a damp t o a f l o o d e d state), t h e s i t u a t i o n i s e n t i r e l y d i f f e r e n t . F o r this condition, the friction levels provided by i n d i v i d u a l r u n w a y s d r o p s i g n i f i c a n t l y from the dry value and there is considerable disparity in the resulting friction level i s due t o d i f f e r e n c e s i n t h e t y p e ofpaveb e t w e e nd i f f e r e n t . s u r f a c e s .T h i sv a r i a n c e ment, the f o r m o f s u r f a c e f i n i s h ( t e x t u r e ) a n d the d r a i n a g e c h a r a c t e r i s t i c s ( s h a p e ) . Degradation of available friction (which i s p a r t i c u l a r l y e v i d e n t when a i r c r a f t o p e r a t e a t high speeds) can have serious implications on safety, regularity or efficiency of operations. The e x t e n t w i l l depend on t h e f r i c t i o n a c t u a l l y r e q u i r e d v e r s u s t h e f r i c t i o n provided. 5.2.3.3 The t y p i c a lr e d u c t i o n of f r i c t i o n when a s u r f a c e i s w e t a n dt h er e d u c t i o n of f r i c t i o n as a i r c r a f t s p e e d i n c r e a s e s are e x p l a i n e d by t h e combined e f f e c t o f v i s c o u s a n dd y n a m i cw a t e rp r e s s u r e st ow h i c ht h et i r e / s u r f a c e i s s u b j e c t e d .T h i sp r e s s u r e c a u s e s a p a r t i a l l o s s of " d r y " c o n t a c t t h e e x t e n t o f w h i c h t e n d s t o i n c r e a s e w i t h s p e e d . There are c o n d i t i o n s w h e r e t h e loss i s p r a c t i c a l l y t o t a l a n d t h e f r i c t i o n d r o p s t o i s i d e n t i f i e d as v i s c o u s ,d y n a m i co rr u b b e r r e v e r t e d aquan e g l i g i b l ev a l u e s .T h i s planing. Themanner i n w h i c h t h e s e phenomena a f f e c t d i f f e r e n t areas of t h e t i r e l s u r f a c e i n t e r f a c e a n d how they change i n s i z e w i t h s p e e d i s i l l u s t r a t e d i n F-igure 5-1.

ICAO 9357 P A R T * 3

b*

484141b OOl1958L 330

Aerodrome Design Manual

3-206 + Direction of motion 1. 2.

3.

Dynamic pressure Viscous pressure "Dry" contact

I

tlre-ground conta

High speed

Figure 5-1.

Areas of t i r e / s u r f a c e i n t e r f a c e

5.2.3.4 I nt h el i g h t of theseconeideratione, i t may be s a i dt h a tt h e wet runway case appears as a significant hazard and a p o t e n t i a l t h r e a t t o f l i g h t o p e r a t i o n s . J3fforts t o achieve a general improvement of t h e s i t u a t i o n are, therefore, well j u s t i Eied. As mentioned earlier, t h e a p p l i c a t i o n of modern runway surface treatment is considered the mst practical and e f f e c t i v e t e c h n i q u e t o i u p r o v e t h e f r i c t i o n characteristics of a wet runway.

5.2.4

Design objectives

5.2.4.1 I nt h el i g h t of the foregoingconsiderations,theobjective6 for runway pavement design, which are s i a & l a r l y a p p l i c a b l e f o r maintenance, can be fornulated as follows:

A runway pavement should be 8 0 designed and laaintained as t o provide a runway s u r f a c e which meets adequately a f u n c t i o n a l requirements a t a l l times t h r o u g h o u t t h e a n t i c i p a t e d l i f e t i m e of t h e pavement, i n p a r t i c u l a r : a)

t o p r o v i d e i n a l l a n t i c i p a t e d c o n d i t i o n e of w e t n e s s , h i g h f r i c t i o n l e v e l s and uniform f r i c t i o n c h a r a c t e r i e t i c e ; and

b)

t o m l n i d z e t h e p o t e n t i a l r i s k of a l l € o m of aquaplaning, i.e. viscous, dynamic andrubber-revertedaquaplaning.Information on these types of aquaplaning i s contained i n t h e Airport Services M a n u a l (Doc 9137-AW898) P a r t 2, Pavement Surface ~onditions.

5.2.4.2 As i s o u t l i n e d below, theprovision of adequate wet runway f r i c t i o n i s closely related to the drainage characteristics of t h e runway surface. The drainage demand i n t u r n i s determined by l o c a l p r e c i p i t a t i o n rates. Drainage demand, t h e r e f o r e , i e a l o c a l v a r i a b l e which w i l l e s s e n t i a l l y d e t e r m i n e t h e e n g i n e e r i n g e f f o r t s and associated investments/costs required to achieve the objective. In general, the higher t h e d r a i n a g e demand, t h e more s t r i n g e n t t h e i n t e r p r e t a t i o n a n d a p p l i c a t i o n of t h e relevant engineering criteria will become.

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5.2.5

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Physical design criteria

5.2.5.1 General. The problem of f r i c t i o n on runway s u r f a c e sa f f e c t e d by water can i n t h e l i g h t of t h e latest state-of-the-art be i n t e r p r e t e d as a generalized drainage problem c o n s i s t i n g of t h r e e d i s t i n c t criteria:

a)

s u r f ace drainage (surf ace shape) ;

b)

t i r e / s u r f a c ei n t e r f a c ed r a i n a g e( m a c r o t e x t u r e ) ;a n d

c)

penetrationdrainage(microtexture).

The t h r e e criteria c a n s i g n i f i c a n t l y b e i n f l u e n c e d by engineering measures and i t i s important t o n o t e t h a t a l l o f them must b e s a t i s f i e d t o a c h i e v e a d e q u a t e f r i c t i o n i n a l l p o s s i b l e c o n d i t i o n s of wetness, i.e. ,from a damp t o a f l o o d e d s u r f a c e . 5.2.5.2 Surface drainage. Surface drainage i s a basic requirement o f utmost importance. It s e r v e s t o m i n i m i z e water depth on t h e s u r f a c e , i n particular i n t h e area of the wheel path. The o b j e c t i v e i s t o d r a i n water o f f t h e runway in t h e s h o r t e s t p a t h p o s s i b l e a n d p a r t i c u l a r l y o u t of t h e area of the wheel path. Adequate surface drainage i s provided primarily by a n a p p r o p r i a t e l y s l o p e d s u r f a c e ( i n b o t h t h e l o n g i t u d i n a l and t r a n s v e r s ed i r e c t i o n s )a n ds u r f a c ee v e n n e s s .D r a i n a g ec a p a b i l i t yc a n ,i na d d i t i o n , be enhanced by s p e c i a l s u r f a c e t r e a t m e n t s s u c h as p r o v i d i n g c l o s e l y s p a c e d t r a n s v e r s e of a s p e c i a l l y t r e a t e d w e a r i n g grooves o r by d r a i n i n g water i n i t i a l l y t h r o u g h t h e v o i d s course(porous f r i c t i o n c o u r s e ) . The e f f e c t i v e n e s s of t h e d r a i n a g e c a p a b i l i t y of modern types of s u r f a c e s i s e v i d e n t in t h a t t h e s u r f a c e s when s u b j e c t e d t o e v e n h i g h r a i n f a l l rates r e t a i n a r a t h e r damp appearance. It s h o u l d b e c l e a r l y u n d e r s t o o d , however, t h a t special s u r f a c e t r e a t m e n t i s n o t a s u b s t i t u t e f o r p o o r runway shape,be i t due t o inadequateslopesorlackofsurfaceevenness. This may be an important consideration when deciding on the most e f f e c t i v e method f o r improving t h e w e t f r i c t i o n c h a r a c t e r istics of a n e x i s t i n g runway surface.

5.2.5.3 T i r e / s u r f a ci en t e r f a cder a i n a g(em a c r o t e x t u r e ) . drainage (under a moving t i r e ) i s twofold:

The purpose of i n t e r f a c e

a)

t o p r e v e n t as f a r as f e a s i b l e r e s i d u a l s u r f ace bulkwater from i n t r u d i n g i n t o t h e f o r w a r d area of t h e i n t e r f a c e ; and

b)

t o d r a i n i n t r u d i n g water t o t h e o u t s i d e

of t h e i n t e r f a c e .

The o b j e c t i v e i s t o a c h i e v e h i g h water discharge rates from under the t i r e with a mininum ofdynamic pressure build-up. It h a s b e e n e s t a b l i s h e d t h a t t h i s c a n o n l y be achieved by providing a s u r f a c e w i t h a n open macrotexture. 5.2.5.4 I n t e r f a c ed r a i n a g e i s a c t u a l l y a dynamic process, i.e., i s highlysuscept ib l e t o t h e s q u a r e of speed.Macrotexture i s therefore particularily important for the p r o v i s i o n of a d e q u a t e f r i c t i o n i n t h e h i g h s p e e d r a n g e . Prom t h e o p e r a e i o n a l aspect, t h i s i s most s i g n i f i c a n t b e c a u s e i t i s i n t h i s speed range where lack of adequate f r i c t i o n i s most c r i t i c a l w i t h respect t o s t o p p i n g d i s t a n c e and d i r e c t i o n a l c o n t r o l capability. 5.2.5.5 I nt h i sc o n t e x t i t is worthwhile t o make a comparison between the texturesappliedinroadconstruction and runways. The smoother textures provided

by

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W Ltfl4b41b DOL9583 $90

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road surfaces can achieve adequate drainage of the footprint of an automobile tire because of the patterned tire treads which significantly contribute to interface tires, however,cannotbeproducedwith similar p a t t e r n e dt r e a d sa n d d r a i n a g e .A i r c r a f t have only a number o f c i r c u m f e r e n t i a l g r o o v e s w h i c h c o n t r i b u t e s u b s t a n t i a l l y less t o t i r e wear. interfacedrainage.Theireffectivenessdiminishesrelativelyquicklywith The more v i t a l f a c t o r , however,which d i c t a t e s t h e m a c r o t e x t u r e r e q u i r e m e n t is the substantially higher speed range in which aircraft operate. This may e x p l a i n why some c o n v e n t i o n a l runway s u r f a c e s which were b u i l t t o s p e c i f i c a t i o n s similar t o r o a d s u r f a c e s ( r e l a t i v e l y c l o s e d - t e x t u r e d ) show a marked drop i n wet f r i c t i o n w i t h i n c r e a s i n g s p e e d and oEten a s u s c e p t i b i l i t y t o dynamic aquaplaning a t comparatively small water depths. 5.2.5.6 Adequate macrotexture can be provided by e i t h e ra s p h a l o tr cement c o n c r e t e o r effectiveness.Withcement s u r f a c e s ,t h o u g hn o tw i t he q u a le f f o r t ,s t a b i l i t y c o n c r e t e pavement s u r f a c e s , t h e r e q u i r e d m a c r o t e x t u r e may b e a c h i e v e d w i t h t r a n s v e r s e wire comb t e x t u r i n g when t h e surface is in t h e p l a s t i c s t a g e o r w i t h c l o s e l y s p a c e d t r a n s v e r s eg r o o v e s .W i t ha s p h a l ts u r f a c e s ,t h ep r o v i s i o n of macrotexture may be achieved by p r o v i d i n g o p e n g r a d e d s u r f a c e s . 5.2.5.7 A f u r t h e rd e s i g n criteria c a l l s f o r best p o s s i b l eu n i f o r m i t y of s u r f a c e t e x t u r e .T h i sr e q u i r e m e n t i s i m p o r t a n t t o a v o i du n d u ef l u c t u a t i o n s in a v a i l a b l e may c a u s e f r i c t i o n s i n c e t h e s e f l u c t u a t i o n s would d e g r a d e a n t i s k i d b r a k i n g e f f i c i e n c y o r t i r e damage. 5.2.5.8 The s u r f a c ef i n i s hc o n s i d e r e d most e f f e c t i v ef r o mt h es t a n d p o i n t of w e t f r i c t i o n i s grooving i n t h e case of P o r t l a n d c e m e n t c o n c r e t e a n d t h e p o r o u s f r i c t i o n by t h e f a c t t h a t c o u r s e in t h e case o f a s p h a l t . T h e i r e f f e c t i v e n e s s c a n b e e x p l a i n e d they not only provide good i n t e r f a c e d r a i n a g e , b u t a l s o c o n t r i b u t e s i g n i f i c a n t l y t o bulkwater drainage. 5.2.5.9

P e n e t r a t i odnr a i n a g(em i c r o t e x t u r e ) . The p u r p o sopefe n e t r a t i odnr a i n a g e "dry" contact between the asperities of t h e s u r f a c e a n d t h e t i r e t r e a d In thepresenceof a t h i n v i s c o u s water f i l m . The v i s c o u s p r e s s u r e s w h i c h i n c r e a s e w i t h s p e e d t e n d t o p r e v e n t d i r e c t c o n t a c t except a t t h o s e l o c a t i o n s o f t h e s u r f a c e w h e r e i s d e f i n e d as a s p e r i t i e sp r e v a i l ,p e n e t r a t i n gt h ev i s c o u sf i l m .T h i sk i n do fr o u g h n e s s microtexture.

is t o

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5.2.5.10 M i c r o t e x t u r e refers t ot h ef i n e - s c a l er o u g h n e s so ft h ei n d i v i d u a al g g r e g a t e of t h e s u r f a c e a n d is h a r d l y d e t e c t a b l e by t h e e y e , however, a s s e s s a b l e by t h e touch.Accordingly,adequatemicrotexturecanbeprovided by t h e a p p r o p r i a t e s e l e c t i o n o f a g g r e g a t e s known t o h a v e a h a r s h s u r f a c e . This excludes i n p a r t i c u l a r a l l p o l i s h a b l e aggregates. w e t surface 5.2.5.11 Macro- a n dm i c r o t e x t u r e are b o t hv i t a lc o n s t i t u e n t sf o r f r i c t i o n , i.e. b o t h must adequately be p r o v i d e d t o a c h i e v e a c c e p t a b l e f r i c t i o n c h a r a c teristics i n a l l d i f f e r e n t c o n d i t i o n s ofwetness. The combined ePfectofmicro-and macrotexture of a s u r f a c e on t h e r e s u l t i n g w e t f r i c t i o n v e r s u s s p e e d is i l l u s t r a t e d i n F i g u r e 5-2 i n d i c a t i n g a l s o t h a t t h e d e s i g n o b j e c t i v e f o r m u l a t e d I n 5.2.4 can b e a c h i e v e d by e n g i n e e r i n g means.

5.2.5.12 A major problemwithmicrotexture i s that: i t c a nc h a n g ew i t h i ns h o r t time p e r i o d s ( u n l i k e macrotexture), w i t h o u t b e i n g e a s i l y d e t e c t e d . A typicalexaapleofthis is the accuwlation of rubber deposits in the touchdown area which w i l l l a r g e l y mask m i c r o t e x t u r ew i t h o u tn e c e s s a r i l yr e d u c i n gm a c r o t e x t u r e . The r e s u l t c a n be a c o n s i d e r a b l e d e c r e a s e i n t h e wet P r i c t i o n l e v e l . T h i s p r o b l e m i s c a t e r e d f o r by

I C A O 9157 P A R T * 3

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P a r t 3 . - Pavements

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p e r i o d i c f r i c t i o n measurementswhich provide a measure of e x i s t i n g m i c r o t e x t u r e . If i t is determined that low w e t f r i c t i o n i s caused by degraded s u r f a c e m i c r o t e x t u r e , t h e r e are methods a v a i l a b l e t o e f f e c t i v e l y r e s t o r e a d e q u a t e m i c r o t e x t u r e f o r e x i s t i n g runway s u r f a c e s (see 5.3). Minimum s p e c i f i c a t i o n s

5.2.6

5.2.6.1 The b a s iecn g i n e e r i n sgp e c i f i c a t i o nfsotrhge e o m e t r i c aslh a p(el o n g i t u dinal slopejtransverse slope/surface evenness) and for the texture (macrotexture) runway s u r f a c e are contained i n Annex 14.’

of a

5.2.6.2 Slopes. All new runways should be designed with uniform transverse p r o f i l e i n accordance with the value of transverse slope recommended i n Annex 14 and with a l o n g i t u d i n a l p r o f i l e as n e a r l y l e v e l as possible. A cambered t r a n s v e r s e s e c t i o n from a c e n t r e crown is p r e f e r a b l e b u t i f f o r a n y r e a s o n t h i s c a n n o t be provided then the s i n g l e runway c r o s s f a l l s h o u l d be c a r e f u l l y r e l a t e d t o p r e v a i l i n g w e t winds t o e n s u r e t h a t s u r f a c e water drainage i s n o t impeded by t h e wind blowing up t h e t r a n s v e r s e s l o p e . ( I n t h e case of s i n g l e c r o s s f a l l s i t may be necessary a t c e r t a i n sites t o p r o v i d e cut‘ . o f f d r a i n a g e a l o n g t h e h i g h e r e d g e t o p r e v e n t water from t h e s h o u l d e r s p i l l i n g o v e r t h e runway s u r f a c e . ) P a r t i c u l a r a t t e n t i o n s h o u l d be paid t o t h e need f o r good drainage i n t h e touchdown zone since aquaplaning induced a t t h i s e a r l y s t a g e of the landing, once s t a r t e d , c a n be s u s t a i n e d by considerably shallower water d e p o s i t s f u r t h e r a l o n g t h e runway

.

5.2.6.3 I tf h e s ei d e a sl h a p e c r i t e r i a are met, aquaplaningincidents will be reduced t o a minimum, but departures from these ideals w i l l r e s u l t f n a n i n c r e a s e of aquaplaning probability, no matter how good t h e f r i c t i o n c h a r a c t e r i s t i c of t h e runway s u r f a c e may be. These comments h o l d true f o r m a j o r r e c o n s t r u c t i o n p r o j e c t s and, i n a d d i t i o n , when o l d runways become due f o r r e s u r f a c i n g t h e o p p o r t u n i t y s h o u l d b e t a k e n , Every improvement whereverpossible, t o improve t h e l e v e l s t o assist surfacedrainage. i n shape helps, no matter how small. 5.2.6.4 Surface evenness. This i s a c o n s t i t u e n t of runway shape which r e q u i r e s is also inportant for the riding quality of equallycarefulattention.Surfaceevenness high speed j e t a i r c r a f t . 5.2.6.5 Requirements f osr u r f a c e v e n n e s s are d e s c r i b e di n Annex 14, Attachment A , 5, and r e f l e c t good e n g i n e e r i n g p r a c t i c e s . F a i l u r e t o meet t h e s e minimm requirements This can be t h e case c a n s e r i o u s l y d e g r a d e s u r f a c e water d r a i n a g e a n d l e a d t o ponding. w i t h a g i n g runways a s a r e s u l t of d i f f e r e n t i a l s e t t l e m e n t and permanent deformation of only f o rt h ec o n s t r u c t i o n of a . t h e pavement surface. Evenness requirementsapplynot new pavement b u t t h r o u g h o u t t h e l i f e of t h e pavement. The maxirmm t o l e r a b l e d e f o r m t i o n as a v i t a l d e s i g n c r i t e r i o n . T h i s may have a s i g n i f i of t h e s u r f a c e s h o u l d b e s p e c i f i e d c a n t impact on t h e d e t e r m i n a t i o n o f t h e most a p p r o p r i a t e t y p e of c o n s t r u c t i o n and t y p e of pavement.

5.2.6.6 With r e s p e c t os u s c e p t i b i l i t yt o ponding when s u r f a c ei r r e g u l a r i t i e s are considerably less develop, runway shapes with m a x i m m permissible transverse slopes affectedthan.thosewithmarginaltransverseslopes. Runways e x h i b i t i n g ponding w i l l normally require a r e s u r f a c i n g a n d r e s h a p i n g t o e f f e c t i v e l y a l l e v i a t e t h e problem.

.

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SURFACE

No.

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FRICTION MICRO-TEXTURE MACRO-TEXTURE

I

I

1(

I

I pmax HARSH micro-textured surfaces permit substantial penetration of thin fluid films; general level of

OPEN macro-textured surfaces provide good bulk drainage of tire-ground contact area. in wet condltions p decreases graduaily with increase in V. Tread grooves havelittle effect. At high speeds p may Increase dueto hysteresis effects.

.

SMOOTH or POLISHED micro-textured surfaces have poor thin-film penetration properties and a generally low level of friction results.

I

II ~

I

I pmax

I

CLOSED macro-textured surfacces give poor contact area drainage. In wet conditions p decreases rapidly with increese in V. Tread grooves are most effective on thistype of surface.

of

2---

I

HARSH micro-textured surfaces permit substantial Penetration of thin fluid level general films; friction is high.

II '

n

V

Pmmx

SMOOTH or POLISHED micro-textured surfeces have poor thin-film penetration properties and a generally low level of frictlon results.

I

I

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Effect of surface texture on tire-surface coefficient of f r i c t i o n

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5.2.6.7 Surface texture. Surface macrotexture requirements are s p e c i f i eidn be less than 1 mm Annex 14 i n terns of average surface texture depth, which should not € o r new s u r f a c e s . It i s a l s o r e c o g n i z e d t h a t t h i s p r o v i s i o n w i l l normally call f o r some form Of s p e c i a l S u r f ace treatment. The m i n i m m v a l u e f o r a v e r a g e t e x t u r e d e p t h h a s b e e n empirically derived and reflects the absolute minimum r e q u i r e d t o p r o v i d e a d e q u a t e interfacedrainage.Highervaluesofaveragetexturedepth may berequiredwhererainf a l l rates a n d i n t e n s i t i e s are a c r i t i c a l f a c t o r t o s a t i s f y i n t e r f a c e d r a i n a g e demand. Surfaces which f a l l s h o r t of t h e minimm r e q u i r e m e n t f o r a v e r a g e s u r f a c e t e x t u r e d e p t h w i l l show poor w e t f r i c t i o n c h a r a c t e r i s t i c s , p a r t i c u l a r l y i f t h e runway i s used by a i r c r a f t w i t hh i g hl a n d i n gs p e e d s . Remedfal a c t i o n i s , t h e r e f o r e ,i m p e r a t i v e . Methods f o r improving the w e t f r i c t i o n c h a r a c t e r i s t i c s of runways are d e s c r i b e d i n 5.3. 5.2.6.8 As o u t l i n e d earlier, uniformity of t h et e x t u r e i s a l s oa ni m p o r t a n t are s e v e r a l s p e c i f i c t y p e s ofsurfaceswhich meet criterion.Inthisrespect,there t h i sr e q u i r e m e n t( s e e 5.3). Thesesurfaces w i l l normallyachieveaveragetexturedepths higher than 1

mm.

5.2.6.9 The macrotexture of a surface does not normally change considerably with time, e x c e p t f o r the touchdown area as a r e s u l t ofrubberdeposits.Therefore,periodic the uncontaminated portion of t h e c o n t r o l of a v a i l a b l e a v e r a g e s u r f a c e t e x t u r e d e p t h o n runway s u r f a c e w i l l only be required

a t long intervals.

5.2.6.10 With r e s p e c t om i c r o t e x t u r et h e r e i s no d i r e c t measure a v a i l a b l e t o d e f i n e t h e r e q u i r e d f i n e scale roughness of the fndividual aggregate i n engineering terms.Accordingly,there are no r e l e v a n ts p e c i f i c a t i o n si n Annex 14. However, from experience i t i s known t h a t good aggregate rmst have a h a r s h s u r f a c e a n d s h a r p e d g e s t o provide good water f i l m p e n e t r a t i o n p r o p e r t i e s . It i s a l s o i m p o r t a n t t h a t t h e a g g r e g a t e beactuallyexposedtothesurfaceandnotcoatedentirely by a smooth material. Since m i c r o t e x t u r e i s a v i t a l c o n s t i t u e n t of wet f r i c t i o n r e g a r d l e s s of speed, the adequacy of microtexture provided by a p a r t i c u l a r s u r f a c e c a n b e a s s e s s e d g e n e r a l l y by f r i c t i o n measurements. Lack of m i c r o t e x t u r e w i l l r e s u l t i n a considerable drop i n f r i c t i o n levels throughout the whole speed range. This w i l l occur even with minor degrees of s u r f a c e w e t n e s s (e.g.,damp). This r a t h e r q u a l i t a t i v e method may be adequate for d e t e c t i n g l a c k of m i c r o t e x t u r e i n o b v i o u s c a s e s . 5.2.6.11 Degradationofmicrotexturecaused by t r a f f i c andweathering may occur, i n time periods and can also change c o n t r a s t to m a c r o t e x t u r e , w i t h i n c o n p a r a t i v e l y s h o r t w i t h t h e o p e r a t i o n a l s t a t e of thesurface.Accordingly,short-termedperiodicchecks by f r i c t i o n measurements are necessary, i n p a r t i c u l a r w i t h r e s p e c t t o t h e touchdown areas where rubber deposits quickly mask microtexture.

5.2.6.12 Runway s u r f a c ef r i c t i o nc a l i b r a t i o n . Annex 14 r e q u i r e s runway s u r f a c e tso be calibrated periodically to verify their friction characteristics when w e t . These f r i c t i o n c h a r a c t e r i s t i c s must n o t f a l l below l e v e l s s p e c i f i e d by t h e State f o r new c o n s t r u c t i o n (minirmm designobjective)andformaintenance. Wet f r i c t i o n l e v e l s , r e f l e c t i n g minimum a c c e p t a b l e limits f o r new construction and maintenance, which are i n Use i n some S t a t e s are given i n Attachment B, 7 of Annex 14.

Aerodrome Design Manual

3-212

5.2.6.13 For thedesign of a new runway, t h e optimum a p p l i c a t i o n of t h eb a s i c engineering criteria f o r runway shape and texture w i l l normally provide a f a i r g u a r a n t e e of a c h i e v i n g l e v e l s w e l l i n excess of t h e a p p l i c a b l e s p e c i f i e d minimum wet f r i c t i o n l e v e l . When l a r g e d e v i a t i o n s f r o m t h e b a s i c s p e c i f i c a t i o n s f o r s h a p e o r t e x t u r e are planned, it will then be advisable to conduct wet f r i c t i o n measurements on d i f f e r e n t t e s t s u r f a c e s i n o r d e r t o assess t h e r e l a t i v e i n f l u e n c e of each parameter on wet friction, prior to deciding on t h e f i n a l d e s i g n . S i m i l a r c o n s i d e r a t i o n e a p p l y f o r s u r f a c e t e x t u r e t r e a t m e n t of e x i s t i n g runways. 5.3 5.3.1

Surfacetreatment

ofrunways

General

5.3.1.1 The methods described i nt h i ss e c t i o n are based on theexperiences of severalStates. It i s important that a f u l l e n g i n e e r i n g a p p r e c i a t i o n o f t h e e x i s t i n g pavement: be made a t each s i t e before any p a r t i c u l a r method i s considered, and that, once selected, t h e method i s s u i t a b l e f o r t h e t y p e s of a i r c r a f t operating. It shouldbe the improvement of t h e f r i c t i o n c h a r a c t e r i s t i c 8 of e x i s t i n g noted that with respect to runway pavements, a reshaping of the pavement may be r e q u i r e d i n c e r t a i n cases p r i o r t o t h e a p p l i c a t i o n of s p e c i a l s u r f a c e t r e a t m n t i n o r d e r t o b e e f f e c t i v e . 5.3.2

Surface dressing

of asphalt

5.3.2.1 Operational considerations. Aircraft with dual tandem undercarriage a t t i r e pressure 1930 Wa and a l l - u p masses exceeding 90 000 kg have been operating regul a r l y f o r a number of years from runways w h i c h h a v e b e e n d e l i b e r a t e l y s u r f a c e d r e s s e d t o iuprovefriction.(Figure 5-3. ) There i s no evidence of an increase i n t i r e wear. 5.3.2.2 Consideration of e x i s t i n g pavement. The o v e r - a lsl h a p ea n dp r o f i l e of t h e e x i s t i n g runway i s not as important as i t i s w i t h o t h e r t r e a t m e n t s and, uhere a number of transverse and longitudinal slope changes occur i n the runway length, surface dressing i s probably the only suitable method s h o r t ofexpensivereshaping. In s p i t e of t h e fact that the over-all shape need not be ideal, nevertheless, for a successful application of this treatment, the compacting equipment m e t be capable of follawing the minor s u r f a c e i r r e g u l a r i t i e s t o e n s u r e a uniform adhesion of the chippings. Where t h i s condit i o n c a n n o t be ensured, a new asphalt wearing course may be necessary before applying t h e s u r f ace dressing. 5.3.2.3 Effectiveness of treatment. A s a t i s f a c t o r syu r f a cde r e s s i n g will i n i t i a l l y raise t h e f r i c t i o n c o e f f i c i e n t of t h e s u r f a c e t o a high value which, thereafter, depending on t h e i n t e n s i t y of t r a f f i c , w i l l slowlydecrease. Normally an e f f e c t i v e l i f e of up t o f i v e y e a r s c a n b e e x p e c t e d .

.

5.3.2.4 Runway ends Runway endsused f o r the start of take-offshould not be treated. Aircraft w i l l scuff in turning, both fuel spillage and heat will s o f t e n t h e binder, and blast will tend t o loosen chippings.

i I

I C A O 9157 P A R T * 3

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4843416 0039588 772

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P a r t 3 . - Pavements

F i g u r e 5-3.

S u r f a c e d r e s s i n g of a s p h a l t

of t hfeo l l o w i n g r o u p s : 5.3.2.5 Chippings. The c h i p p i n g s may be from one Basalt, G a b b r o ,G r a n i t e ,G r i t s t o n e ,H o r n f e l s ,P o r p h y r yo rq u a r t z i t e . 5.3.2.6 M e c h a n i c agl r i t t e r . The c h i p p i n g s are d i s t r i b u t e d by a m e c h a n i c agl r i t t e r of a p p r o v e d t y p e i n c o r p o r a t i n g a m e c h a n i c a l f e e d c a p a b l e of e n s u r i n g t h a t t h e s e l e c t e d r a t e of s p r e a d i s r i g i d l y m a i n t a i n e d t h r o u g h o u t t h e work. 5.3.2.7 R e s t r i c t i o nds u r i n g bad weather. Work r m snt obtcea r r i e o d udt u r i n g periods of rain, snow o r s l e e t o r o n f r o z e n s u r f a c e s o r on those on which water i s l y i n g . When w e a t h e r c o n d i t i o n s d i c t a t e , s u i t a b l e p r o t e c t i o n mst b e a f f o r d e d t o t h e chippingsduringdelivery. 5.3.2.8 E x i s t i np g icto v e r sg, u l l g yr a t i n g s and aerodrome markings. These rmst b e p r o t e c t e d by m a s k i n g , a n d t h e s u r f a c e d r e s s i n g f i n i s h e d n e a t l y a r o u n d them. maskingof the aerodrome markings i s not indicated, they may b e o b l i t e r a t e d .

When

. m e d i a t e lbye f o rsep r a y i ntgh e 5.3.2.9 P r e p a r a t i o n of t heex i s t i nsgu r f a c i n gI m binder, the existing surfaces m s t bethoroughlycleaned by mechanical brooms, supplemented by handbrooming i f n e c e s s a r y . All v e g e t a t i o n , l o o s e m a t e r i a l s , d u s t a n d d e b r i s , etc., must b e removed as i n d i c a t e d .

a t t h es e l e c t e d 5.3.2.10 A p p l i c a t i o n of s u r f a c eb i n d e r . The b i n d e r must b ea p p l i e d rate without variation and s o t h a t a f i l m of uniform thickness results. Particular care must b e t a k e n t o a v o i d d r i p p i n g , s p i l l i n g a n d c r e a t i n g areas of e x c e s s i v e t h i c k n e s s . 5.3.2.11 A p p l i c a t i o n of coated chippings. The t e m p e r a t u r e of t hceh i p p i n g s when applied to the sprayed surface binder must b e n o t less t h a n 83°C when u s i n g b i t u m e n

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binder and 72OC when u s i n g t a r b i n d e r . B e f o r e a n d d u r i n g t h e r o l l i n g o p e r a t i o n a n y b a l d p a t c h e s nust b e c o v e r e d w i t h f r e s h c h i p p i n g s . 5.3.2.12 and before

Rollin%

The coated chippings

must b reo l l e di m m e d i a t e l ya f t esrp r e a d i n g

loss of heat.

of t h eg r i t t i n go p e r a t i o n 5.3.2.13 F i n a l sweeping and r o l l i n gW . i t h i nt h r e ed a y s a l l l o o s e c h i p p i n g s must be swept from the surface with hand-broom, loaded onto trucks at and removed as d i r e c t e d . Then t h e e n t i r e s u r f a c e uust a g a i n b e t h o r o u g h l y r o l l e d

l e a s t t h r e e more tires. All chippings m s t a d h e r e f i r m l y t o t h e f i n i s h e d s u r f a c e w h i c h should be of uniform texture and colour. The s u r f a c e rmst b e e n t i r e l y f r e e of i r r e g u l a r i t i e s due t o scabbing,scraping,dragging,droppings,excessiveoverlapping,faulty i t mst be l e f t c l e a n a n d t i d y . l a n e or t r a n s v e r s e j u n c t i o n s , o r o t h e r d e f e c t s , a n d Under no circumstances should swept up chippings be reused. pavements Grooving 5.3.3 of

are n o p e r a t i o n aol b j e c t i o ntstoh e 5.3.3.1 Operational considerations. There all t y p e s of a i r c r a f t from grooving of e x i s t i n g s u r f a c e s . E x p e r i e n c e o f o p e r a t i n g a number o f y e a r s i n d i c a t e s t h a t t h e r e i s no limit w i t h i n t h e grooved surfaces over w i l l be foreseeable future to the aircrft size, loading or type €or which such surfaces satisfactory.There i s i n c o n c l u s i v e e v i d e n c e of a s l i g h t l y g r e a t e r rate of t i r e wear under some o p e r a t i o n a l c o n d i t i o n s . 5.3.3.2 Methods ofgroovingincludethesawingofgrooves in e x i e t i n go rp r o p e r l y c u r e d a s p h a l t ( F i g u r e 5-41 o r P o r t l a n d cenrent c o n c r e t e p a v e m e n t s , a n d t h e g r o o v i n g o r wire combingof P o r t l a n d cement c o n c r e t e w h i l e i t is i n t h e p l a s t i c c o n d i t i o n . Based on c u r r e n t t e c h n i q u e s , sawed grooves provide a more uniform width, depth, and alignment. This method i s t h e most e f f e c t i v e means ofremoving water f r o m t h e p a v e m e n t / t i r e i n t e r face and improves the pavement skid resistance. However, p l a s t i c g r o o v i n g a n d wire combing are a l s o e f f e c t i v e i n I m p r o v i n g d r a i n a g e a n d f r i c t i o n c h a r a c t e r i s t i c s of pavement s u r f a c e s . They are cheaper eo c o n s t m c t t h a n t h e sawed g r o o v e s , p a r t i c u l a r l y w h e r e are u s e d i n p a v e m e n t s . T h e r e f o r e t h e c o s t - b e n e f i t r e l a t i o n s h i p v e r yh a r da g g r e g a t e s should be considered in deciding which grooving technique should be used for a p a r t i c u l a r runway.

F i g u r e 5-4. Grooving of a s p h a l ts u r f a c e (Note.-Scale shows 2.5 cm d i v i s i o n s )

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5.3.3.3 F a c t o r tso be considered. j u s t i f y i n g g r o o v i n g o f runways:

The f o l l o w i n fga c t o rssh o u l b dce o n s i d e r e idn

historical review of aircraft accidents/incidents related planing a t a i r p o r t f a c i l i t y ; wetness frequency (review

t o aqua-

of a n n u a l r a i n f a l l r a t e and i n t e n s i t y ) ;

areas, d e p r e s s i o n s , mounds, transverse and longitudinal slopes, flat o r a n y o t h e r a b n o r m a l i t i e s - t h a t may a f f e c t water run-off; s u r f a c e t e x t u r e q u a l i t y as t o s l i p p e r i n e s s u n d e r d r y o r w e t condit i o n s .P o l i s h i n go fa g g r e g a t e ,i m p r o p e r seal c o a t i n g ,i n a d e q u a t e dcrotexture/macrotexture, and contaminant buildup are some examples of c o n d i t i o n s w h i c h may a f f e c t t h e l o s s o f s u r f a c e f r i c t i o n ; terrain limitations such

as d r o p - o f f s a t t h e e n d s

ofrunway

end safety

a reas ; adequacy of number a n d l e n g t h o f a v a i l a b l e r u n w a y s ; crosswind effects, particularly and the strength and condition

when low f r i c t i o n f a c t o r s p r e v a i l ;

of e x i s t i n g runway pavements.

5.3.3.4 E v a l u a t i o n of e x i s t i n g pavement. A s p h a lstu r f a c e s mst be examined to deterdnethattheexistingwearingcourse i s dense,stableandwell-compacted. If t h e are s u r f a c e e x h i b i t s f r e t t i n g o r where l a r g e p a r t i c l e f r a c t i o n s o f c o a r s e a g g r e g a t e exposed on the surface itself, then other methods w i l l need t o b e c o n s i d e r e d , o r resurfacing w i l l have to be undertaken before grooving i s p u t i n hand. Rigidpavement i s sound, f r e e o f s c a l i n g o r must be examined to ensure that the existing surface itself, e x t e n s i v e s p a l l s , o r " w o r k i n gc r a c k s " .A p a r tf r o mt h ec o n d i t i o no ft h es u r f a c e t h e r a t i o b e t w e e nt r a n s v e r s ea n dl o n g i t u d i n a ls l o p e s becomes i m p o r t a n t . I f t h e l o n g i t u d i n a l s l o p e s a r e s u c h t h a t t h e water r u n - o f f i s d i r e c t e d a l o n g t h e runway i n s t e a d o f c l e a r i n g q u i c k l y t o t h e runway s i d e d r a i n s , t h e n a c o n d i t i o n c o u l d a r i s e when t h e grooves would f i l l w i t h f r e e water, f a i l t o d r a i n q u i c k l y a n d p o s s i b l y e n c o u r a g e same r e a s o n , s u r f a c e s w i t h d e p r e s s e d a r e a s s h o u l d b e r e p a i r e d o r a q u a p l a n i n g .F o rt h e replaced before grooving. 5.3.3.5 E f f e c t i v e n e s s of t r e a t m e n T t . r a n s v e r sger o o v i n g w i l l . a l w a yrse s u litn a measurableincreaseofthefrictioncoefficient,thoughtheextentoftheimprovement w i l l berelatedtothequality of t h e e x i s t i n g s u r f a c e . The d u r a t i o n of t h i s improveclimate and ment w i l l d e p e n d o n t h e p r o p e r t i e s o f t h e a s p h a l t w e a r i n g c o u r s e , t h e rate t r a f f i c .E x p e r i e n c eh a s shown t h a t g r o o v i n g d o e s n o t r e s u l t i n a n i n c r e a s e o f t h e of d e t e r i o r a t i o no ft h ea s p h a l t . The improvement a l s o a p p l i e s t o r i g i d pavement s u r f a c e s as t h e y are n o t a d v e r s e l y a f f e c t e d by t h eg r o o v i n g . No grooves becoming clogged with dust, industrial waste, o r o t h e r c o n t a m i n a n t s h a v e b e e n f o u n d a l t h o u g h some minor rubber deposits have been observed.

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3-21.6

Figure 5-5.

Grooving w i t h disc flails

Figure 5-6.

Grooving with saws

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5.3.3.6 Technique. The s u r f a c e i s tbgoer o o v eadc r o st h se runway a t r i g ha tn g l e s t o t h e runway e d g e s o r p a r a l l e l t o n o n - p e r p e n d i c u l a r t r a n s v e r s e j o i n t s , w h e r e a p p l i cable, with grooves which follow across the runway i n a c o n t i n u o u s l i n e w i t h o u t b r e a k . Themachine f o r g r o o v i n g w i l l i n c o r p o r a t e d i s c f l a i l s ( F i g u r e 5-5) o r f l a i l c u t t e r s o r a sawingmachine(Figure 5-6) i n c o r p o r a t i n g a minimum of 12 b l a d e s . Sawingmachines i n c l u d e water t a n k s a n d p r e s s u r e s p r a y s . Commonly u s e d g r o o v e c o n f i g u r a t i o n s are 3 mm wide by 3 mm deep a t a p p r o x i m a t e l y 2 5 mm c e n t r e s , o r 6 mm by 6 mm w i t h a c e n t r e s p a c i n g of 31

mm.

5.3.3.7 The grooves may b et e r m i n a t e dw i t h i n 3 m o ft h e runway pavementedge to a l l o wa d e q u a t es p a c ef o rt h eo p e r a t i o n of thegroovingequipment.Tolerancesshouldbe e s t a b l i s h e dt od e f i n eg r o o v ea l i g n m e n t ,d e p t h ,w i d t ha n ds p a c i n g .S u g g e s t e dt o l e r a n c e s are +- 40 mm i n a l i g n m e n t f o r 22 m, a n d a v e r a g e d e p t h o r width 1.5 Groovesshouldnot 75 mm t o t r a n s v e r s e j o i n t s . M a g o n a l o r l o n g i t u d i n a l s a w k e r f s where be cut closer than l i g h t i n g c a b l e s are i n s t a l l e d s h o u l d b e a v o i d e d , G r o o v e s may becontinuedthrough longitudinal construction joints. Extreme care mustbeexercised when g r o o v i n g n e a r i n runway l i g h t i n g f i x t u r e s a n d s u b - s u r f a c e w i r i n g . A 60 cm e a s e m e n t o n e a c h s i d e of t h e l i g h t f i x t u r e i s recommended t o a v o i d c o n t a c t by t h e g r o o v i n g m a c h i n e . C o n t r a c t s s h o u l d is specifythecontractor'sliabilityfor damage t o l i g h t f i x t u r e s andcable.Clean-up e x t r e m e l yi m p o r t a n ta n ds h o u l db ec o n t i n u o u st h r o u g h o u tt h eg r o o v i n go p e r a t i o n . The waste material c o l l e c t e d d u r i n g t h e g r o o v i n g o p e r a t i o n mst b e d i s p o s e d of by f l u s h i n g I f waste material i s f l u s h e d , t h e s p e c i f i c a t i o n s w i t h water, sweeping, o r vacuuming. s h o u l d s t a t e w h e t h e r t h e a i r p o r t owner o r c o n t r a c t o r i s r e s p o n s i b l e f o r f u r n i s h i n g w a t e r forcleanupoperations.Waste material c o l l e c t e d d u r i n g t h e g r o o v i n g o p e r a t i o n =st n o t be allowed t o e n t e r t h e a i r p o r t s t o r m o r s a n i t a r y sewer, as t h e material w i l l e v e n t u a l l y clog the system. Failure to remove t h e m a t e r i a l . c a n create c o n d i t i o n s t h a t w i l l b e hazardous t o a i r c r a f t o p e r a t i o n s . f

mm.

5.3.3.8 Plastig c r o o v e as n d w i r e comb. G r o o v ecsa b nceo n s t r u c t e d i n new P o r t l a n d . cementconcretepavementswhile in the plastic condition, The " p l a s t i c g r o o v i n g " o r wire comb (see F i g u r e 5-7) t e c h n i q u e c a n b e i n c l u d e d as a n i n t e g r a l p a r t of t h e p a v i n g A test sectionshouldbeconstructedtodemonstratetheperformance of. train operation. t h e p l a s t i c g r o o v i n g o r wire combingequipmentand set a s t a n d a r d f o r a c c e p t a n c e of t h e colqplete product

.

5.3.3.9 T e c h n i q u eT. o l e r a n c efsoprl a s t igcr o o v i nsgh o u lbdees t a b l i s h etdo are d e f i n eg r o o v ea l i g n m e n t ,d e p t h ,w i d t h ,a n ds p a c i n g .S u g g e s t e dt o l e r a n c e s f 7.5 mm i n a l i g n m e n t f o r 22 m; minimum d e p t h 3 mm, maximum d e p t h 9.5 mm; minimum w i d t h 3 mm , maximm w i d t h 9.5 mm; minirmm s p a c i n g 28 m m , maxirmm s p a c i n g 50 mm c e n t r e t o centre. Tolerances for w i r e combing s h o u l d r e s u l t i n a n a v e r a g e 3 mm x 3 mm x 12 mm configuration.

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Aerodrome ~~

F i g u r e 5-7.

Hew concretesurfacingtextured

Figure 5-8.

with wire comb

ExistingPortland cement concrete before and a f t e r s c o r i n g

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The junctionofgrooveface and pavement surfaceshould be squared or roundedorslightlychamfered.Hand-finishingtools,shapedtomatchthegrooved be provided. The c o n t r a c t o rs h o u l df u r n i s h a " b r i d g e "f o r workmen t o surface,should and work from t o r e p a i r any imperfect areas. The equipmentshouldbedesigned c o n s t r u c t e d so t h a t i t c a n b e c o n t r o l l e d t o - g r a d e andbe capable of p r o d u c i n g t h e f i n i s h If pavement g r i n d i n g i s used t o meet s p e c i f i e ds u r f a c et o l e r a n c e s , i t should required. beaccomplished i n a d i r e c t i o n p a r a l l e l t o t h e formed grooves.

5.3.3.10

Grooving runway i n t e r s e c t i o n s

5.3.3.11 General. Runway i n t e r s e c t i o n rse q u i r e a d e c i s i o n as t o which runway's continuousgrooving i s t ob ea p p l i e d . The s e l e c t i o no ft h ep r e f e r r e d runway w i l l normallybedictated by s u r f a c e d r a i n a g e a s p e c t s , e x c e p t t h a t i f t h i s c r i t e r i o n d o e s n o t f a v o u r e i t h e r runway, c o n s i d e r a t i o n w i l l be gzven t o o t h e r r e l e v a n t criteria. 5.3.3.12 Criteria. The main p h y s i c aclr i t e r i a n i s s u r f a cder a i n a g e . d r a i n a g e characteristics are similar f o r t h e g r o o v i n g p a t t e r n o f e i t h e r c o n s i d e r a t i o ns h o u l db eg i v e nt ot h ef o l l o w i n go p e r a t i o n a l criteria:

Where runway,

- a i r c r a f t groundspeedregime; - touchdown area; and - riskassessment. 5.3.3.13 Surface drainage. The primary purpose of grooving a runway s u r f a c e i s t o are enhancesurfacedrainage. Hence, t h ep r e f e r r e d runway i s t h e one on whichgrooves a l i g n e d c l o s e s t t o t h e d i r e c t i o n of the major downslope within the intersection area. The majordownslopecanbedetermined from a grade contour map. 5.3.3.14 The above aspect i s e s s e n t i abl e c a u s ei n t e r s e c t i o na r e a isn v o l v e , by d e s i g n , r a t h e r f l a t g r a d e s( t os a t i s f yt h er e q u i r e m e n tt op r o v i d es m o o t ht r a n s i t i o nt o a i r c r a f t t r a v e l l i n g a t highspeeds)and,therefore, are s u s c e p t i b l e t o water ponding. 5.3.3.15 Where a p p r o p r i a t ec, o n s i d e r a t i o n may b g eiven to a d d i t i o n adl r a i n a g e channels across the secondary runway where t h e g r o o v e p a t t e r n t e r m i n a t e s i n o r d e r t o area. prevent water from this o r i g i n from a f f e c t i n g t h e i n t e r s e c t i o n 5.3.3.16 Aircraft speed. Since grooving i s p a r t i c u l a r leyf f e c t i vree g a r d i n g wet s u r f a c e f r i c t i o n characteristics i n t h e h i g h groundspeedregime,preferenceshould be are f r e q u e n t l y a t t a i n e d a t t h e g i v e nt ot h a t runway on which thehighergroundspeeds intersection. 5.3.3.17 Touchdown area. P r o v i d e tdhsep e e cdr i t e r i o d n o ens oatp p l yt,h e runway on whfch t h e i n t e r s e c t i o n forms p a r t of t h e touchdown area shouldbepreferredbecause grooving w i l l provide rapid wheel spin-up on touchdown i n p a r t i c u l a r when t h e s u r f a c e i s wet. 5.3.3.18 Risk assessments. Eventually, the selection of the primary runway can be based on a no p e r a t i o n a l judgementof r i s k sf o ro v e r r u n s( r e j e c t e dt a k eo f fo rl a n d i n g ) takingintoaccount:

-

runway u s e ( t a k e

of f / l a n d i n g ) ;

runway l e n g t h s ; a v a i l a b l e rrunway end s a f e t y areas;

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Figure 5-9.

Figure 5-10.

Scoring w i t h diamond segmented cutting drum

Reflex percussive technique

- Portland

cement concrete

1

P a r t 3.-

5.3.4

3-221

-

movement rates; and

-

p a r t i c u l a ro p e r a t i n gc o n d i t i o n s .

Scoring cement of

concrete

5.3.4.1 O p e r a t i o n aclo n s i d e r a t i o n s . There do n oatp p e atbroaenoyp e r a t i o n a l o b j e c t i o n st ot h es c o r i n go fe x i s t i n gP o r t l a n dc o n c r e t es u r f a c e s( F i g u r e5 - 8 ) , method o f treatment seems t o b e s u i t a b l e f o r a l l types of a i r c r a f t .

and t h i s

damaged orpoorly formed j o i n & , o r on which l a i t a n c e h a s l e d t o - e x t e n s i v e s p a l l i n g o f t h es u r f a c e , would b ee q u a l l yd i f f i c u l tt os c o r e .I ft h ee x i s t i n gs u r f a c e i s reasonably f r e e of t h e s e d e f e c t s , t h e r e are no o t h e r e n g i n e e r i n g l i m i t a t i o n s t o s c o r i n g . 5.3.4.3 E f f e c t i v e n e sot srfe a t m e nTt .r a n s v e r ssec o r i n g of concrete improves considerably the friction characteristics ofpavements i n i t i a l l y t e x t u r e d a t t h e time of constructionwithbolts,burlaporbroom. The u s e f u l l i f e of t h e t r e a t m e n t d e p e n d s o n t h e f r e q u e n c y of t r a f f i c b u t i n g e n e r a l t h e s c o r i n g r e m a i n s e f f e c t i v e f o r t h e l i f e o f the concrete. 5.3.4.4 Runway ends. Runway e n d s h o u l db el e fut n s c o r e dt o make i t easier t o wash down and c l e a n o f f f u e l a n d o i l d r o p p i n g s . Moreover, engine blast can be more damagingon a s c o r e d t h a n o n a n u n t e x u r e d s u r f a c e . The d i r e c t i o n a l c o n t r o l of a n a i r c r a f t moving f r o m t h e t a x i w a y o n t o t h e runway can become reduced,presumablybecause a possibilityofan of a tendency of t h e tires t o t r a c k i n t h e s c o r e s . I n a d d i t i o n , i n c r e a s e i n t i r e wear i n t u r n i n g c a n n o t b e t o t a l l y d i s c o u n t e d . 5.3.4.5 Technique. An a c c e p t a b l e "trial" area should be a v a i l a b l feoirn s p e c t i o n and i t i s recommended t h a t t h i s b e p r o v i d e d a t t h e aerodrome t o d e t e r m i n e a p r e c i s e texture depth requirement, as t h i s w i l l t e n d t o v a r y w i t h t h e q u a l i t y of t h e c o n c r e t e . by a s i n g l e p a s s of a c u t t i n g drum ( F i g u r e 5-9) Therunway i s t o b e s c o r e d t r a n s v e r s e l y i n c o r p o r a t i n g n o t less t h a n 5 0 c i r c u l a r s e g m e n t e d diamond s a w b l a d e s p e r 30 c m w i d t h of drum. The drum i s t o be set a t 3 mm s e t t i n g o n a m u l t i - w h e e l e d a r t i c u l a t e d f r a m e w i t h outrigger wheels, fixed to give a u n i f o r m d e p t h of s c o r i n g o v e r t h e e n t i r e s u r f a c e of t h e runway t o e n s u r e t h e r e m o v a l o f a l l laitanceandtheexposureoftheaggregate. It should be noted t h a t s c o r i n g g e n e r a t e s a g r e a t d e a l of d u s t d u r i n g t r e a t m e n t a n d it is n e c e s s a r y t o sweep and wash down t h e s u r f a c e b e f o r e o p e r a t i o n s re-start. 5.3.5

Rpeefrlceuxtsescihvnei q u e

5.3.5.1 The r e f l e x p e r c u s s i v tee c h n i q u e i s p r e d o m i n a n t l ayp p l i e fdogr r o o v i n o gf a cost-effective alternative to saw-cut grooving e x i s t i n g runway s u r f a c e s a n d r e p r e s e n t s techniques. It h a sb e e ns u c c e s s f u l l ya p p l i e d on v a r i o u st y p e so f runway s u r f a c e s t o provideadequategrooving. The t e c h n i q u e c a n a l s o e f f e c t i v e l y beused f o r o t h e r purposes, such as removal of r u b b e r d e p o s i t s i n touchdown zone areas o r f o r t h e r e s t o r a t i o n of micro/macrotexture of a d e g r a d e d e x i s t i n g runway s u r f a c e . 5.3.5.2 The r e f l e xp e r c u s s i v et e c h n i q u eu s e s t a r s h a p e dopr e n t a g o n adl i s k f l a i l s . The s p e c i f i c a t i o n of t h e c r o s s s e c t i o n a n d s p a c i n g o f t h e g r o o v e s w i l l be d i c t a t e d p r i m a r i l y by t h e d r a i n a g e r e q u i r e m e n t s d e t e r m i n e d f r o m l o c a l p r e c i p i t a t i o n c o n d i t i o n sa n dt h es l o p e so ft h e runway s u r f a c e .F o r cement c o n c r e t e s u r f a c e s , t h e pitch ranges normally from 42 mm t o 48 mm and f o r a s p h a l t s u r f a c e s f r o m 42 mm t o 56 mm, r e s p e c t i v e l y .F o re i t h e rt y p eo fs u r f a c e , however, l o c a l c o n d i t i o n s may r e q u i r e c l o s e r spacingsbetween two c o n s e c u t i v e g r o o v e s t o s a t i s f y d r a i n a g e demand, down t o 32 mm. On t h e o t h e r hand, higher spacings are o f t e n u s e d a t runway endswhere a i r c r a f t l i n e u p , i n ordertoavoidhighstresses on the t r e a d s of s c r u b b i n g a i r c r a f t tires. T y p i c a l c r o s s s e c t i o n s f o r g r o o v i n g cement c o n c r e t e and a s p h a l t s u r f a c e s are: 31f 8 f 89 No. 2

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Figure 5-11.

Reflex percussive technique

Figure 5-12.

31/8/89 No. 2

- Asphalt

Porous f r i c t i o n coursesurfacing

surface

ICAO 7357 P A R T * 3 P a r t 3.-

** =

4843436 0039598 631

=

Pavements Portland cement Width/depth/pitch 10/3/27 concrete: edges and trough rounded (see Figure

3-223

mm,

A s p h a sl tu r f a c eW : idth/depth/pitch 9/3/58 mm, edges and trough rounded (see Figure

5-10)

5-11).

5.3.5.3 The s u r f a c e of t h eP o r t l a n d c e m e nct o n c r e t eo ar s p h a lst u r f a c e i s t ob e g r o o v e d p e r p e n d i c u l a r t o t h e runway c e n t r e l i n e o r p a r a l l e l t o n o n - p e r p e n d i c u l a r t r a n s verse j o i n t s , w h e r e a p p l i c a b l e , i n c o n t i n u o u s u n i n t e r r u p t e d l i n e s t e r m i n a t i n g a p p r o x i mately 3 m b e f o r e t h e e d g e o f t h e runway. On concreterunways, a s t r i p o n b o t h s i d e s i s t o be l e f t ungrooved t o p r e v e n t w e a k e n i n g of t h e i n d i v i d u a l adjacent to each joint slabedges. After grooving,debrisand a l l l o o s e material are t o b e removed s a t i s f a c torily. 5.3.6

Po f rrioccu ot isuorns e

5.3.6.1 The p o r o ufsr i c t i ocno u r sceo n s i s t s of an open-graded, bituminous surface course composed ofmineralaggregate and bituminous material, mixed i n a c e n t r a l m i x i n g 5-12). T h i sf r i c t i o nc o u r s e is p l a n t , andplaced on a p r e p a r e ds u r f a c e( F i g u r e d e l i b e r a t e l yd e s i g n e dn o to n l yt oi m p r o v et h es k i d - r e s i s t a n c eb u tt or e d u c ea q u a p l a n i n g i n c i d e n c e by providing a "honeycomb" m a t e r i a l t o e n s u r e a q u i c kd r a i n a g eo f water from t h e pavement s u r f a c ed i r e c tt ot h eu n d e r l y i n gi m p e r v i o u sa s p h a l t . The p o r o u sf r i c t i o n c o u r s e i s able,because of i t s p o r o s i t y and d u r a b i l i t y , t o m a i n t a i n o v e r a l o n gp e r i o d a c o n s t a n t and r e l a t i v e l y h i g h w e t f r i c t i o n v a l u e . 5.3.6.2 L i m i t a t i o n s of p o r o ufsr i c t i ocno u r s eF.r i c t i ocno u r s e s of t h iks i n d s h o u l do n l yb el a i d on new runways of good s h a p e ,o r on reshapedrunwaysapproachingthe criteria expectedfor new runways. They mustalwaysbeoverdenselygradedimpervious a s p h a l tw e a r i n gc o u r s e s of h i g h s t a b i l i t y . Both of t h e s er e q u i r e m e n t s are n e c e s s a r yt o e n s u r e a quickflow of t h ew a t e rb e l o wt h ef r i c t i o nc o u r s ea n do v e rt h ei m p e r v i o u s a s p h a l tt ot h e runway drainagechannels. 5.3.6.3 Runway ends. The p o r o ufsr i c t i ocno u r s e is n o t recommended atth e runway ends. O i l and f u e ld r o p p i n g s would c l o gt h ei n t e r s t i c e s and s o f t e nt h eb i t u m e nb i n d e r , and jet e n g i n eh e a t would s o f t e nt h e material which b l a s t would thenerode.Erosion of e n g i n e would t e n d t o be deeperthan on a normaldenseasphaltandthepossibility damage t h r o u g hi n g e s t i o n of p a r t i c l e s ofrunway m a t e r i a ls h o u l dn o tb ed i s c o u n t e d . Scuffingmightoccur i n t u r n i n g movements d u r i n gt h e f i r s t few weeks a f t e r l a y i n g , For of brushedorgrooved t h e s er e a s o n s , i t i s recommended t h a t runway endsbeconstructed c o n c r e t e , o r of a denseasphalt. 5.3.6.4 Aggregate. The a g g r e g a tceo n s i s t s of c r u s h esdt o n ec ,r u s h egdr a v eol ,r c r u s h e ds l a gw i t ho rw i t h o u to t h e ri n e r tf i n e l yd i v i d e dm i n e r a la g g r e g a t e . The aggreg a t e i s composed of c l e a n ,s o u n d ,t o u g h ,d u r a b l ep a r t i c l e s ,f r e ef r o mc l a yb a l l s , Organicmatter, and o t h e rd e l e t e r i o u ss u b s t a n c e s . The t y p e and gradeofbituminous material i s t ob eb a s e d on g e o g r a p h i c a ll o c a t i o n and climatic c o n d i t i o n s . The maximum mixingtemperature and c o n t r o l l i n g s p e c i f i c a t i o n i s a l s o t o b e s p e c i f i e d . 5.3.6.5 Weather and seasonal limitations. The p o r o ufsr i c t i o cn o u r s e i s t ob e c o n s t r u c t e d o n l y o n a d r y s u r f a c e when t h e a t m o s p h e r i c t e m p e r a t u r e i s loo C a n d r i s i n g ( a t calm wind c o n d i t i o n s ) a n d when t h e w e a t h e r i s n o t f o g g y o r r a i n y . 5.3.6.6 P r e p a r a t i o n of e x i s t i nsgu r f a c e sR. e h a b i l i t a t i oonafenx i s t i npga v e m e n t for the placement of a porousfrictioncourseincludes:constructionofbituminous of overlay, jolnt sealing, crack repair, reconstruction of failed pavementandcleaning grease,oil,andfuel s p i l l s . I m m e d i a t e l yb e f o r ep l a c i n gt h ep o r o u sf r i c t i o nc o u r s e , a l l l o o s e o r d e l e t e r i o u s material w i t h power the underlying course i s to be cleared of

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4 8 4 5 4 L b 0019599 558

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b l m e r s , power b r o o m , o r hand broom as directed. A t a c k c o a t i s t o be placed on those e x i s t i n g s u r f a c e s w h e r e a t a c k c o a t i s necessary for bonding the porous friction course totheexistingsurface. If e m l s i f i e d a s p h a l t is used,placement of the porous frictioncoursecanbeappliediunnediately. However, i f cutbackasphalt i s used, placement of porous f r i c t i o n c o u r s e must be delayed u n t i l t h e t a c k c o a t h a s p r o p e r l y aired. 5.3.7

Emulsified asphalt s l u r r y seal

5.3.7.1 The e m l s i f i e da s p h a l ts l u r r y seal c o u r s ec o n s i s t s of a mlxture of emlsifled asphalt, mineral aggregate, and water, properly proportioned, mixed, and spread evenly on a prepared underlying course of existing wearing course. The aggregate c o n s i s t s of sound and durable natural or manufactured sand, slag, crusher fines, crushed stone, or crushed stone and rock dust, or a combinationthereof. The aggregate is t o b e clean and free from vegetable matter, d i r t , dust, and other deleterious substances. The aggregate is t o have a g r a d a t i o n w i t h i n t h e limits shown below.

GRADATION OF AGGREGATES Sieve Percentage Size

by w e i g ph at s s i ns gi e v e s QPe 11 Type 111

Type 1

-_ ~~~

~~

9.5 mm 4.75 mm 100 2.36 uun 45-70 65-90 90-100 45-70 65-90 1.18 mm 28-50 600 micro m 40-60 300 micro m 25-42 150 micro m 15-30 10-21 75 micro m 5-15 10-20

~~

100 9U-lfiO 19-34 39-50 18-30

100 7*9a

12-25 7-1 11 5-€5

R e s i daus p a lh a l t 10-16 7.5-13.5 6.5-12 content-percentage dry aggregate Kilograms of aggregate per square metre

35.8.2.4-1-5-8.1.401.8

5.3.7.2 The Type I gradation is u s e df o r maximum crackpenetrationand is u s u a l l y used i n low d e n s i t y t r a f f i c a r e a s w h e r e t h e prinrary objective i s sealing. The Type 11 gradation i s used t o s e a l andimprove s k i d r e s i s t a n c e . The Type 111 gradation i s used to correct surface conditions and provide skid resistance. 5.3.7.3 Mineral f i l l e r i s onlyused i f needed t o improve t h ew o r k a b i l i t y of t h e mix o r t o improve t h e g r a d a t i o n of the aggregate. The f i l l e r i s considered as p a r t of the blended aggregate. 5.3.7.4 Tack coat. The t a c kc o a t i s a d i l u t e da s p h a l te m l s i o n of t h e same type specified for the slurry mix. The r a t i o o f a s p h a l t e r m l s i o n t o water should be 1 t o 3. 5.3.7.5 Weather l i m i t a t i o n s . The s l u r r y seal is n oat p p l i e d if e i t h e tr h e pavement o r t h e a i r temperature is 13O C o r below o r when r a i n i s imminent. Slurry placed a t lower temperatures usually w i l l not cure properly due to poor dehydration and poor asphalt coalescence.

31/8/89 No. 2

I C A O 7357 P A R T t 3 t t

P a r t 3 . - Pavements

a

= 4843436

OOL7600 O T T

= 3-2248

5.3.7.6 C l e a n i n ge x i s t i n gs u r f a c eP. r i o trop l a c i n gt h et a c kc o aat n ds l u r r ys e a l c o a t , u n s a t i s f a c t o r y areas a r e t o b e r e p a i r e d a n d t h e s u r f a c e c l e a n e d of d u s t , d i r t , o r of o b j e c t i o n a b l e s u r f a c e f i l m . Any o t h e r l o o s e f o r e i g n matter, g r e a s e , o i l , o r a n y t y p e s t a n d a r d c l e a n i n g method i s a c c e p t a b l e e x c e p t t h a t water f l u s h i n g i s p e r m i t t e d i n areas where considerable cracks a r e p r e s e n t i n t h e pavement s u r f a c e . Any p a i n t e d s t r i p e s o r markingon t h e s u r f a c e t o b e t r e a t e d are t o b e removed b e f o r e a p p l y i n g t h e t a c k c o a t . When t h e s u r f a c e of t h e e x i s t i n g pavement o r b a s e i s i r r e g u l a r o r b r o k e n , i t nust be repaired or brought to uniform grade and cross section. Cracks wider than 10 mm must be s e a l e d w i t h c o m p a t i b l e j o i n t sealer p r i o r t o a p p l y i n g t h e s l u r r y s e a l .

5.3.7.7 Application of bituminous tack coat. Following the preparation for s e a l i n g , a p p l i c a t i o n of t h e d i l u t e d e m u l s i o n t a c k c o a t i s done by means of a p r e s s u r e The t a c k c o a t i s t o b e a p p l l e d a t d i s t r i b u t o r i n amountsbetween 0.23 t o 0.68 L/rn2. least two h o u r s b e f o r e t h e s l u r r y seal, b u t w i t h i n t h e same day. 5.3.7.8 The main items of d e s i g ni ne m l s i f i e da s p h a l ts l u r r y seals are a g g r e g a t e g r a d a t i o n ,e m l s i f i e da s p h a l tc o n t e n t ,a n dc o n s i s t e n c y of themixture. The a g g r e g a t e s , e m l s i f i e d a s p h a l t , and water should form a c r e a r n y - t e x t u r e d s l u r r y t h a t , when spread, w i l l flow i n a wave ahead of the strike-off squeegee. This w i l l allaw t h e s l u r r y t o flow down i n t o t h e c r a c k s i n t h e pavement and f i l l them b e f o r e t h e s t r i k e - o f f p a s s e s over, The c u r e d s l u r r y i s t o have a homogeneous appearance, f i l l a l l c r a c k s , a d h e r e f i r m l y t o t h e s u r f a c e , and have skid resistant texture.

a

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CHAPTER 6 .

6.1

-

PROTECTION O F ASPHALT PAVEMENTS

The problem

6.1.1 Since petroleum-base fuels and lubricants contain solvents for asphalt, t h e i r s p i l l a g e o n a s p h a l t i c pavements creates problems.Severity t o t h e d e g r e e of exposure t o t h e p e n e t r a t i n g s o l v e n t s .

of p r o b l e m is r e l a t e d

6.1.2 The h i g h l v y o l a t i lg e a s o l i n eas n h digo h c t a n feu e l s of the past have been less of a problem s i n c e t h e y q u i c k l y e v a p o r a t e d when spillage occurred and systems using t h e s ef u e l sh a v ep r o v i d e d good containment.Massiveandfrequentlyrepeatedspillage course,sincesuchfuels are e x c e l l e n t s o l v e n t s . F u e l s p i l l a g e canbe a problem,of s u r f a c e d as a p a r t i c u l a r p r o b l e m w i t h t h e a d v e n t of t u r b i n e a n d j e t engines. The j e t f u e l s i n v o l v e d do n o t r e a d i l y e v a p o r a t e a n d e a r l y e n g i n e kerosene and light oil s y s t e m s r o u t i n e l y s p i l l e d - q u a n t i t i e s of f u e l on engine shutdown. H y d r a u l i c f l u i d s a n d less r a p i d l y t h a n j e t f u e l s , c a n l u b r i c a t i n g o i l s , which evaporate or "cure out" even a l s o c a u s e o r c o n t r i b u t e t o problems.

a

6.1.3 S i n c teh se e v e r i t y of a d v e r s e f f e c t s of s p i l l a g eo na s p h a l t pavements i s related to exposure, concern m s t be f o r t h e number of times s p i l l a g e i s repeated i n one location, the length of time t h e s p i l l e d f u e l o r o i l remainson(or i n ) t h e pavement, and the location and extent of spillage on the pavement. It has been found that a s i n g l e s p i l l a g e of j e t f u e l , a n d e v e n s e v e r a l s p i l l a g e s i n t h e same l o c a t i o n when t h e r e i s time f o r e v a p o r a t i o n a n d c u r i n g b e t w e e n s p i l l a g e s , do not normally have a s i g n i f i c a n t adverseeffectonthe pavement. However, some s t a i n i n g and a render pavement are t o be expected during the curing period. 6.1.4 S p i l l a g ecsarne s u lftr o m r o u t i noep e r a t i o nssu c h as e n g i nseh u t d o w n , fuel tank sediment draining, consistent use of solvents for cleaning of engine or etc. Morecommonly s p i l l a g e i s t h e r e s u l t of f u e l h a n d l i n g hydraulicsystemelements, o p e r a t i o n s , of s p i l l e d o i l o r h y d r a u l i c f l u i d , o r a c c u r m l a t e d d r i p p i n g s f r o m e n g i n e o i l leakage or mishandling. 6.1.5 Thus l o c a t i o n s of concern on pavements a r teh o s e where a i r c r a f t are r e g u l a r l yf u e l l e d ,p a r k e d ,o rs e r v i c e d . The broadareasoflandingandtaxiingoperaconcern, since even spillages attendant to aircraft accidents will t i o n s w i l l not beof be minimized by c l e a n - u p a n d r e p r e s e n t o n l y a s i n g l e s p i l l a g e which w i l l cure without permanent damage. Even f u e l burnedon t h e a s p h a l t s u r f a c e w i l l normallyonlyleave a s u r f a c e scar of no s t r u c t u r a l s i g n i f i c a n c e . 6.1.6 I n areas where s p i l l a g eo c c u r rs e p e a t e d l yo sr p i l l e df u eol or irl e m a i n s for long periods on the pavement t h e s o l v e n t a c t i o n s o f t e n s t h e a s p h a l t and reduces adhesion to the surface aggregate. While heat from the sun or warm a i r conditions help evaporate solvents and re-cure the asphalt, the elevated temperatures contribute to the The r e s u l t of t h e s p i l l a g e , a g g r a v a t e d by h e a t , c a n be shoving of a s p h a l ts o f t e n i n g . t h e a s p h a l t mix, t i r e t r e a d p r i n t i n g , t r a c k i n g o f a s p h a l t t o a d j a c e n t areas o r product i o n of l o o s e material, and pavement a b r a s i o n a l s o p r o d u c i n g l o o s e material on t h e pavement surface. In maintenanceand work areas a s p h a l t and g r i t picked up by t o o l s , shoes, and clothing can b e t r a n s f e r r e d t o m e c h a n i c a l s y s t e m .

3-225

3-226 ~~

~

~~~

Aerodrome Design Zlanual

6.1-7 The s u r f a ctee x t u raen cdo n d i t i o o npf a v e r r e n ths a v e a b e a r i n g on t h e s e v e r i t y of t h e problem. Open o r porouspavements will be more r e a d i l y p e n e t r a t e d by f u e l o r o i l and w i l l slow the evaporation and re-cure process. It has been found that traEfic tends t o c l o s e t h e s u r f a c e a n d rubber tire t r a f f i c , w h e t h e r f r o m r o l l i n g o r well s e a l e d , are a p a r t i c u l a r source o f retardfuelpenetration.Cracksandjoints,not access f o r f u e l t o deeper zones w i t h i n t h e p a v e n e n t , p r o v i d e trouble.Theseprovide greater surface areas for fuel intake, and retain fuel rmch l o n g e r t h e r e b y r e t a r d i n g evaporation and cure. Low areas which will r e t a i n o r pond f l u i d s , w h e t h e r a d j a c e n t t o cracks o r j o i n t s o r in c e n t r a l areas ofpavement, vi11 p r o l o n g e x p o s u r e t o s p i l l e d fuel. 6.2

Treatmentoftheproblem

6.2.1 The best treatment is a v o i d a n c eo sf p i l l a g ea n dt h i s may be p o s s i b l e i n many cases of o p e r a t i o n a l s p i l l a g e a n d so= a c c i d e n t a l s p i l l a g e . F u e l t a u k s e d i m e n t be allowed on t h e pavement.Drippanscanbeused drainagecanbecaughtandneednot for oil drip locations and for bleeding or servicing of hydraulic system. “rays p r a c t i c a l t o catch e n g i n e s h u t d o w n e p i l l a g e o r small q u a n t i t i e s o f r e f u e l l i n g spillage.

may be

6.2.2 Removal of t h es p i l l e df u e l o r o i l a n dr e d u c t i o n of expoeurethroughclean up is t h e n e x t a s p e c t o f treatment. S p i l l e d f u e l o r o i l can be f luehed off the pavement w i t h water. Addition of d e t e r g e n t s assist8 t h e p r o c e s s o f s e p a r a t i n g t h e f u e l a n d e s p e c i a l l y o i l f r o m t h e a s p h a l t pavement. While t h i s h a s b e e n a common t r e a t m e n t t h e r e are b e g i n n i n g t o be environmental complaints from effects of t h e r u n - o f f . A vacuuming process, w i t h s u i t a b l e e q u i p m e n t , c a n b e u e e d t o remove s p i l l e d f u e l a n d some f u e l materials can a l s o b e u s e d for f u e l and o i l pickup with recovery i s possible.Absorbent suitablearrangementfordisposal. Rolls, pads, and granular materials are a l l usedand in some cases wringers are u s e d f o r f u e l r e c o v e r y . T h e r e i s another aspect of absorpt i o n by g r a n u l a r m a t e r i a l s i n s p i l l a g e areas t o c o n s i d e r . A c c u n u l a t i o n s of dust and s a n d , e i t h e r blown o r man placed, will a b s o r b small s p i l l a g e s , o i l d r i p p i n g s , etc., and f orm a mat w h i c h c o n t a i n s t h e s p i l l e d material and reduces i t s a v a i l a b i l i t y f o r s o i l i n g ofpersonnelandequipment. While t h i s t e m p o r a r i l y f a c i l i t a t e s movement of p e r s o n n e l i t can greatly increase exposure of the paveent to effects of the fuel and oil. 6.2.3 Since problems are aggravated by r e p e a t e edx p o s u rtesop i l l a g e , i t is sometimes possible t o r e l o c a t e a i r c r a f t p a r k i n g , f u e l l i n g , or s e r v i c i n g p o s i t i o n s t o ameliorate the deterioration.

6.2.4 Spillage problems cannot develop i fs p i l l e df u e lo ro i l i s n oat l l o w e dt o come i n c o n t a c t w i t h t h e a s p h a l t pavement. P r o t e c t i v ec o a t i n g sh a v ea c c o r d i n g l yb e e n developed t o p r o v i d e a barrier between t h e f u e l o r o i l a n d t h e pavement,which i s t h e n n o t a f f e c t e d by t h e s p i l l e d f u e l o r o i l .

6.3

P r o t e c t i v ec o a t i n g s

6.3.1 P r o t e c t i vceo a t i n g materials are g e n e r a l llyi q u i d s , some h e a t e tdo become liquid, which when s p r e a d on t h e pavement c u r e o r set t o become a p r o t e c t i v e c o a t i n g . These are commonly r e f e r r e d t o as seal c o a t s when comton s p r a y a p p l i c a t i o n a n d b i t u m i i n any of nous materials are involved. Most of t h e l i q u i d materials can be applied s e v e r a l ways i n c l u d i n g s p r a y i n g u s i n g h a n d s p r a y s o r a s p h a l t d i s t r i b u t o r e q u i p m e n t , pouring on the surface and spreading using squeezes, rolling onto the surface with paint rollers,andapplicationorspreadingusingbrushes.Singleandmltipleapplications

I C A O 9157 P A R T * 3

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6.3.2 Coating materials i ne m l s i o n form can be extended and premixed with fine aggregate t o form a s l u r r y a n d a p p l i e d as a s l u r r y seal. * S i n g l e o r m l t i p l e a p p l i c a t i o n sc a nb eu s e dh e r ea l s o . Two l a y e r a p p l i c a t i o n s are common. 6.3.3 Thin overlays of materials n oat f f e c t e d p r o t e c t a s p h a l t pavements.Conventionalconstruction very unconventional materials are employed. . 6.4

by s p i l l a g ce a n b ae p p l i e d to methods are a p p l i c a b l e u n l e s s some

Materials f o rp r o t e c t i v ec o a t i n p s

6.4.1 C o a l - t apr i t c h i s o n l ys l i g h t l ys o l u b l et oi n s o l u b l ei nt h el i g hpt e t r o are s o l v e n t s f o r a s p h a l t s a n d c a n b e employed, i n m c h leum f r a c t i o n s ( n a p t h a s ) w h i c h t h e same way as i s a s p h a l t , in pavement a p p l i c a t i o n s . Also, i n many places,depending upon r e l a t i v e a v a i l a b i l i t y a n d e c o n o m i c c i r c u m s t a n c e s , t a r has been cost competitive a b i n d e r f o r pavements. Thus c o a l - t a r p i t c h withasphaltforsprayapplicationsandas is used as a p r o t e c t i v e s e a l e r * * a n d i s t h e b a s i c i n g r e d i e n t i n v a r i o u s c o m m e r c i a l l y o f f e r e d sealers f o r p r o t e c t i v e c o a t i n g a p p l i c a t i o n s .

6.4.3 S e a l i n g materials are o f f e r e d which employ epoxies and polymers of v a r i o u s t y p e s e i t h e r . a l o n e o r i n a bituminousbase,whichcanbe tar or asphalt. While t h e s e have attributes which should make them e f f e c t i v e , e x p e r i e n c e w i t h t h e i r a p p l i c a t i o n i n t h e f i e l d i s limited.Therefore t r i a l t e s t a p p l i c a t i o n s are recommended t o h e l p assess e f f e c t i v e n e s sb e f o r eb r o a da p p l i c a t i o n s are undertaken.These materials range i n p r i c e i n t h e U n i t e d States up t o 2 0 times t h a t of l i q u i d a s p h a l t s . 6.4.4 Tar-rubber binder materials and, i n a t l e a sotnien s t a n c ee,p o x y - a s p h a l t binder of a t y p e u s e d f o r b r i d g e d e c k p r o t e c t i o n , h a v e b e e n p l a c e d as o v e r l a y s of a s p h a l t pavements t o p r o v i d e p r o t e c t i o n f r o m f u e l s p i l l a g e a l o n g w i t h s t r u c t u r a l upgrading.These are e f f e c t i v e s o long as c r a c k i n g c a n b e c o n t r o l l e d ( p r e v e n t e d o r Cost o f t h e t a r - r u b b e r b i n d e r i s perhaps twice t h e c o s t of a s p h a l t c r a c k sk e p ts e a l e d ) .

* **

ASTM D-3910 Standard Practice of Design, Testing, and Construction of Slurry Seal, ASTM D-3423 S t a n d a r d P r a c t i c e f o r A p p l i c a t i o n of Emulsified Coal-Tar (Mineral Colloid Type).

Pitch

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Aerodrome Design

mix w h i l e t h e e p o x y a s p h a l t may r u n t o f i v e rims t h e c o s t of a s p h a l t mix but can placed as a very t h i n (20 m m ) overlay.

6.5

be

Application

6.5.1 S u r f a c etrsoe c e i vper o t e c t i vceo a t i n gm s et be thoroughly cleaned. Any s u r f a c e f i l m ; o f oil need t o be c a r e f u l l y removed. Areas of pavementwhich ha= becoms a f f e c t e d by p r i o r f u e l s p i l l a g e and any badly cracked areas nust be removed and replaced with sound pavement and these patches should be thoroughly cured (2 to 4 weeks) p r i o r t o the sealing. A l but very narrow cracks mst be cleaned and f i l l e d u i t h c r a c k f i l l e r .

6.502 Methods of a p p l i c a t i o snh o u l fdo l l o w s t a n d a r pd r a c t i c e a6 reco-nded by a i r f i e l d o r highway a u t h o r i t i e s , t r a d e a s s o c i a t i o n s , o r t h e p r o d u c t m a n u f a c t u r e r . Seal coat guidance can be found i n ASTM D-3423 o r t h e United States FAA Engineering Brief No. 22, Appendix B. Slurry seal guidance w i l l be found i n ASTM D-3410.

6.5.3 CoPPmonly, s i n g l ea p p l i c a t i o n s of s e a l o rs l u r r y seal are such a s t o provide Om3 t o 0.5 kg/m2 of r e s i d u a l bitumen. Two and even three applications are usual. Surfaces should be moist but not wet for euulsion applications and temperatures should be favourable both for application and eubsequent cure 10°C t o 27'C i s d e a i r able. A lower limit: i s 7'C and favourable temperatures should continue a t l e a s t 4 hours as recommnded a f t e r placement. Epoxy andpolymeric seals should be applied and cured f o r t h e i n d i v i d u a l material, but coagaonly a p p l i c a t i o n r a t e s are 0.3 t o 0.4 kgln?.

-

6.6

Protection gained

6.6.1 Durability and wear can vary with the saterials a n da p p l i c a t i o n st,h e surface cleaning and preparation, maintenance of the protective coating, and of course exposure t o s p i l l a g e and traffic. Testing and experience have shown t h a t good coatings, well a p p l i e d t o c l e a n well prepared surfaces and properly maintained, w i l l provide s a t i s f a c t o r y p r o t e c t i o n i n wst cases. I n areas ofverysevereexposure, as a t c e n t r a l f u e l l i n g p o i n t s , no protective coatings have been found to be e n t i r e l y s a t i s f a c t o r y . 6.6.2 Iont h etrh atnh e most s e v e rsep i l l a gleo c a t i o nusn s a t i s f a c t o rbye h a v i o u r can be experienced when elements of good p r a c t i c e are ignored. Sonre m a t e r i a l f o r m l a t i o n s a n d a p p l i c a t i o n methods, e i t h e r i n d i v i d u a l l y o r i n c o n c e r t , c a n r e s u l t i n i m p e r f e c t coverage by t h e s e a l c o a t i n g . B u b b l e s c a n e x i s t a t a p p l i c a t i o n (somztlmes called f i s h e y e s ) and leave holes in the coating or bubbles can form beneath a coating after cure and on breaking leave holes, and coatings can shrink and crack. Improper surface cleaning can result in a poor bond and peeling of the coating. And c r a c k s i n t h e c o a t e d pavement w i l l t e n d t o c o r n t h r o u g h t h e p r o t e c t i v e s u r f a c e c o a t i n g . 6.6.3 When f u e l cangainaccessthroughholesorcracks i nt h es e a lc o a t , through peeled areas, or through cracks reflected from the lower pavement, o r when f u e l s a t u r a t e d pavement has not been removed and i s covered by t h e seal coat, conditions are worsened r a t h e r t h a n irsproved by t h e s e a l s i n c e , i n a d d i t i o n t o n o t p r e v e n t i n g a c c e s s of t h e s p i l l e d f u e l or o i l t o t h e a s p h a l t , t h e seal c o a t g r e a t l y i n h i b i t s t h e e v a p o r a t i o n and cure-out of t h e s p i l l a g e . 6.6.4 Overlays of t a r r u b b ebr i n d egr i v se p t l l a g pe r o t e c t i o n and a r ne ostu b j e c t t o bubbleholes,peeling,or wear through. T a r r u b b e r overlays are s u b j e c t t o shrinkage, cracking and to crack reflection from underlying pavements. They mst be properly compacted s i n c e pavements having voids of as rmch as 6 per cent w i l l be porous enough t o permit penetration of j e t f u e l .

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Maintenance consideration

Maintenance includes clean-up of s p i l l s as discussed earlier under "treatment of t h e problem". Ponding mst be prevented t o avoid extending exposure from is concerned with maintaining integrity of t h e p r o t e c t i v e spillage.Othermaintenance coating.Cracks must be k e p t s e a l e d w i t h a f u e l r e s i s t a n t sealer. Retreatment mst be employed when d e t e r i o r a t i o n , wear t h r o u g h , o r p e e l i n g l e a d s t o o p e n i n g s i n t h e c o a t i n g . i s r e q u i r e dt h e nt h es u r f a c e , Accidental scars must beclosed.Ifasphaltpatching after suitable cure, needs to be coated against spillage effects.

6.7.1

6.8

Some r e l a t e dc o n c e r n s

6.8.1 Some s e aclo a tps r o v i d e reduced s k i rde s i s t a n c e , and while f u erl e s i s t a n t coatings are n o t commonly employed onaerodromes i n areas of s e v e r e s k i d d i n g p o t e n t i a l , . t h e problem,should i t intrude, can be treated through embedmentof sand size aggregate in t h e s e a l c o a t b e f o r e f i n a l c u r e . 6.8.2 As earlier mentioned t h e r e i s d e v e l o p i ncgo n c e rfnotrhfel u s h i n g of s p i l l e d f u e l and o i l , andofchemicals employed t o assist t h e removalof o i l s , i n t o a d j a c e n td r a i n s . Catchmentsand a c c e p t a b l ed i s p o s a l practices may be required. 6.8.3 S p i l l e df u e l which f i n d s i t s way i n t o s u b s u r f a cd e r a i nas n d c u l v e r tcs a n Such s p i l l a g e c a n d e v e l o p e x p l o s i v e f u e l - a i r m i x t u r e s i n t h e be a s a f e t y h a z a r d . The r i s k t o l i f e and confined drains and a s p a r k i g n i t i o n w i l l r e s u l t i n a n e x p l o s i o n . property can be r e a l and consequential. 6.8.4 There can be a q u e s t i o n as to t h ed e s i r a b i l i t y of r o l l i n g seal c o a t s . R o l l i n g c a n improve f i l m a d h e s i o n , and, as earlier mentioned, c l o s e s u r f a c e p o r e s a n d r e d u c ef u e lp e n e t r a t i o n .G e n e r a l l y ,t h e r e f o r e ,r o l l i n g of bituminous seals u s i n g f l a t ( n o t r e a d ) r u b b e r t i r e r o l l e r s s h o u l d be b e n e f i c i a l , b u t w h e t h e r t h e r e s u l t i n g improvement w a r r a n t s t h e r o l l i n g e f f o r t h a s not been e s t a b l i s h e d . Steel w h e e l r o l l i n g would not be of benefit and may damage t h e c o a t i n g . Any r o l l i n g of polymeric seals mightbe undesirable, and supplier recommendations should be followed.

CHAPTER 7 .

7.1

-

STRUCTURAL CONCERNS FOP CULVERTS AND BRIDGES

Problemdescription

7.1.1 S u b a u r f a cset r u c t u r efsodr r a i n a goearc c e s s uust commonly be crossed by pavementswhichsupportaircraft.Such f a c i l i t i e s are s u b j e c t t o t h e a d d e d l o a d i n g imposed by t h e a i r c r a f t sometimes d i r e c t l y as i n t h e c a s e of bridges, subeurface terminal facilities, and the like, but more o f t e n i n d i r e c t l y as l o a d i n g t r a n s m i t t e d t o buried pipes and culverts through the soil layer beneath the pavement. 7.1.2 T h e sseu b s u r f a cset r u c t u r em s et be c o n s i d e r eidcno n n e l t i ow n i tehv a l u a t i o n of pavement s t r e n g t h . The p a t t e r n of stresses induced by s u r f a c e wheel load8 as t h e y are t r a n s d t t e d downward are n o t t h e same o n t h e s u b e u r f a c e s t r u c t u r e s as on t h e is notonlybecausetheseetructures are not a t s u b g r a d e l e v e l b u t a l s o subgrade.This becausethepresence of t h e s t r u c t u r e d i s t o r t e t h e p a t t e r n s . Thus t h e c o n s i d e r a t i o n s which permit uae of the ACN-PCN method t o limit pavement overloadtng are n o t n e c e s s a r i l y adequatetoprotectsubsurfacestructures. I n BOE cases t h e s u b a u r f a c e s t r u c t u r e can be the critical or limiting element thereby necessitating the reporting of a lover PCN f o r t h e pavement. 7.1.3 I nt h e design of new f a c i l i t i e e care m a tb eg i v e nt ot h es t r u c t u r a l only f o r t h e c o n t e m p l a t e d d e s i g n adequacy of pfpes, culverts, and bridged crossings, not l o a d i n g s b u t for p o s s i b l e f u t u r e l o a d i n g s t o a v o i d a need f o r v e r y c o s t l y c o r r e c t i v e t r e a t m e n t s made n e c e s s a r y by a growth i n a i r c r a f t l o a d i n g s . 7.2

Types of s u b s t r u c t u r e s

7.2.1 Probably the most c o m n a n lde a sat p p a r e n t buried s t r u c t u r e s a t a e r o dromes are p i p e s f a c i l i t a t i n g d r a i n a g e o f s u r f a c e o r s u b s u r f a c e water. These can range i n diameter from 100 mm t o 4 o r 5 m and i n cover depth from 300 m t o 50 P and wre i n t h e c a s e o f h i g h embankments, a n d t h e y c a n b e q u i t e s t i f f i n r e l a t i o n t o t h e s u r r o u n d i n g soil(rigidpipe)orquiteeasilydeforsed by v e r t i c a l l o a d i n g ( f l e x i b l e p i p e ) . The but t h e r e are a l s o p i p e s most common r i g i d p i p e i s made of reinforced cement concrete made of p l a i n cement c o n c r e t e o r c l a y . The l a t t e r p i p e s are of n e c e s e i t y smaller i n diameter. Themost common f l e x i b l e p i p e i s of corrugated steel b u t t h e r e are a l s o corrugated aluminium pipes, several types of p l a s t i c p i p e s , b l t u r n i n i z e d f i b r e p i p e s a n d o t h e r s .P i p ei n s t a l l a t i o n s are d e s i g n e d t a k i n g i n t o a c c o u n t s u c h f a c t o r s as t h e p i p e type,thebedding,backfill,installation materials a n d c o n d i t i o n s , t h e embankment d e p t h and the load imposed by i t , a n d s u r f a c e l i v e l o a d s t o be s u e t a i n e d . 7.2.2 Box c u l v e r tw s h i c h are e i t h e sr q u a r eo r e c t a n g u l a r in shape are commonly used for stream crossings beneath pavements. They a r e d e s i g n e d f o r t h e h y d r a u l i c f l a w andtheloadsto besupported. They are u s u a l l y o f cast in ziti! reinforcedcement concrete.Spanbetweenside walls canvaryfromabout 1 t o 5 m. Smaller box d r a i n s are o f t e n u s e d i n wide apron areas d i r e c t l y b e n e a t h p a v e m e n t s as surface flow c o l l e c t o r s . 7.2.3 Arches of s t r u c t u r a l metal p l a t e s , of t h et y p eu s e d for c o n s t r u c t i n gl a r g e d i a m e t e r p i p e s are sometimes used i n p r e f e r e n c e t o s h o r t b r i d g e s t o s p a n stream o r pavement c r o s s i n g s . I n such cases, s o i l i s p l a c e d b e s i d e a n d a b o v e t h e a r c h u p eo subgrade l e v e l a n d t h e pavement constructedthereon. In rare cases t u n n e l s may p a s s b e n e a t h aerodromepavements.

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7.2.4 Bridges are used in a number of cases f o r highways t o pass beneath taxiways and runways and, i n c r e a s i n g l y , s u b s u r f a c e t e r m i n a l f a c i l i t i e s a r e p l a c e d b e n e a t h are designed t o s u p p o r t t h e u s i n g a i r c r a f t and s t r u c t u r e apronsandtaxiways.These dead loads. Also runway extensionsover water a r e sometimes placed on bridgessupported on piles a n d t h e s e mst be designed t o accommodate a i r c r a f t l o a d s i n a d d i t i o n t o t h e i r dead weight. 7.3

Some guiding concepts

7.3.1 The d i s c u s s i o ni nC h a p t e r 3, 3; 2.4, on A i r c r a f t Loading i s p e r t i n e n t o concepts of d i s t r i b u t i o n o f stresses from surface loads within embankments beneath pavements. High stress s u r f a c e l o a d s are d i s t r i b u t e d by t h e pavement s t r u c t u r e a n d as t h e loads extend downward they are f u r t h e r d i s t r i b u t e d o v e r w i d e r areas with consequent As t h e p a t t e r n of stress goesdeeper and extends over r e d u c t i o n i n stress magnitudes. wider areas, t h e e f f e c t s o f a d j a c e n t w h e e l s o v e r l a p l e a d i n g t o d o u b l i n g o r e v e n g r e a t e r multiplying of t h e stress induced by onewheel. The d e e p e r t h e p a t t e r n e x t e n d s , t h e farther apart individual wheels can be and still have interacting effects. These are t h e p a t t e r n s of stresses introduced by t h e l i v e l o a d s ( a i r c r a f t ) i n t o t h e ground beneath pavements,and a l o n g w i t h t h e mass of t h e s o i l and pavement, r e p r e s e n t t h e magnitudes of stresses o r l o a d i n g d e l i v e r e d t o b u r i e d s t r u c t u r e s . 7.3.2 The presence of a b u r i e ds t r u c t u r e (which does not act i nt h e same manner as t h e s o i l i t d i s p l a c e s ) h a s a s i g n i f i c a n t impact on t h e p a t t e r n of l i v e and dead load stresses (ambient stresses) induced by t h e s u r f a c e l o a d s , pavement a n d b a c k f i l l material. A c o n c r e t e p i p e , f o r i n s t a n c e , is rmch s t i f f e r i n t h e v e r t i c a l d i r e c t i o n t h a n is theadjacentsoil. Thus c o m p r e s s i o n ( v e r t i c a l d e f l e x i o n ) of t h e s o i l under a i r c r a f t l o a d i n g r e s u l t s i n a r e l a t i v e upward t h r u s t of t h e r i g i d p i p e i n t o t h e s o i l w i t h a constress and loading.This i s why some deepsequentaccumulation of greater than ambient l y b u r i e d r i g i d p i p e s are p r o t e c t e d by s o f t ( b a l e d straw, l o o s e s o i l , e t c . ) z o n e s above t h ep i p e .I ns u c h cases, t h e v e r t i c a l s t i f f n e s s of t h e p i p e a n d s o f t zone i s less than t h e s t i f f n e s s of s o i l b e s i d e t h e p i p e a n d stresses are a c c u m l a t e d more by t h e a d j a c e n t s o i l . This i s a l s o why t h e c h a r a c t e r and c o n d i t i o n of beddingand b a c k f i l l are very important. 7.3.3 Box c u l v e r t s accurnulate stresses i nt h e same way as r i g i dp i p e sb utth e impactonthestructure is n o t t h e same. The v e r t i c a l s i d e w a l l s of box c u l v e r t s w h i l e nuch s t i f f e r t h a n t h e s o i l are f a r s t r o n g e r t h a n n e c e s s a r y t o s u s t a i n t h e a c c u n u l a t e d stresses o r l o a d i n g , and t h e s p a n between s i d e w a l l s i s less s t i f f t h a n t h e s i d e w a l l s and are small, however, s u b j e c t t o r e d u c e d stress. It shouldbenotedthatthesereductions and are reduced from the higher stresses accumulated on t h e s t i f f box c u l v e r t . 7.3.4 Metal and o t h efrl e x i b l p eipes are g e n e r a l l y less s t i f v f e r t i c a l l yt h a n stress a c c u m l a t i o n s i n t h e manner of r i g i d p i p e s . adjacent soil and not subject to However, metal p i p e s are very s t i f f in circumference and some l a r g e r d i a m e t e r p i p e s w i t h deep corrugations and located near the surface can accumulate more t h a n ambient loading, be r e l a t i v e l y s t i f f s t r u c t u r e s . Large metal a r c h e s w i t h f i x e d f o o t i n g s c a n a l s o 7.4 7.4.1

Evaluation of s u b s u r f a cset r u c t u r e s General

7.4.1.1 Every s u b s u r f a c se t r u c t u r b e eneath a pavement mst be considered i n connexion with evaluation of t h e pavement. And w h i l e s p e c i f i c d e t e r m i n a t i o n s would i n each case require careful structural analysis, the likelihood that a particular

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s t r u c t u r e would prove more critical t h a n t h e pavement i n l i m l t i n g a i r c r a f t l o a d s depends g r e a t l y on the type, size, and location of the structure. Accordingly, certain guidance can be suggested t o assist i n determining which structures can, a t small rlsk, be considered not to be l i m i t i n g , whichones are marginal and need t o be c a r e f u l l y considered, and which require study and analysis to d e f i n e l o a d l i m i t a t i o n s o r needed strengthening. 7.4.2

Deeply b u s trriue cdt u r e s

7.4.2.1 The l i v el o a d on d e e p l yb u r i e ds t r u c t u r e st e n d st o be only a mall f r a c t i o n of the dead load so t h a t p i p e s o r c u l v e r t s of moderate s i z e and smaller, which do not accumulate an undue s h a r e of t h e l i v e l o a d , will n o t l i m i t s u r f a c e l o a d i n g s . This w i l l i n c l u d e p i p e d i a m e t e r s o r s t r u c t u r e s p a n s u p t o a b o u t o n e - t h i r d o f t h e p r o t e c t i v e cover (distance betweenpavement surfaceandtop o f pipeorculvert).Table 7-1 i n d i c a t e s t h e t h i c k n e s s of protective cover of s o i l and pavement s t r u c t u r e above d r a i n a g e s t r u c t u r e s of not too large span which will s p r e a d t h e l o a d s u f f i c i e n t l y , on considering combining of eff ects from adjacent wheels, to reduce the pressure induced t h e s t r u c t u r e by a i r c r a f t ( l i v e ) l o a d s t o less than 10 per cent of t h e e a r t h ( d e a d ) added 10 per cent of pressure w i l l e x c e e d t h e s t r u c t u r a l load. It i s n o t l i k e l y t h a t a n capacity of in-eervice pipes or culverts. Where a i r c r a f t t o be supportedhave t i r e l o a d s g r e a t e r t h a n 200 kt? somewhat greater cover depths may be needed t o a t t a i n t h e 10 per cent limitation on increased (live load) pressure.

Table 7-1.

Protective cover needed over structures beneath aerodrome Number of wheels" 1 2 4 8

16

pavements

Cover depth i n metree

4 5 6

7.5 9.5

Pipes and culverts of the sizes indicated (about one-hird of the depth of cover) and a t depths equal to or greater than that shown i n Table 7-1 should not require a s e p a r a t e l o a d l i m i t a t i o n of the overlying pavement. 7.4.2.2 Structures a t shallower depths need more detailed examination. Whether l o a d l i m i t a t i o n s beyond those for p r o t e c t i o n o f t h e p a v e e n t may be needed w i l l depend on r i g i d i t y of t h e p i p e o r culvert, bedding and backfill, pavement stucture, and conservatism of the o r i g i n a l d e s i g n . S u f f i d e n t analysis should be made either t o c o n f i r m that the buried structure does not require a more c r i t i c a l l o a d l i m i t a t i o n t h a n t h e pavement o r t o e s t a b l i s h a p p r o p r i a t e l o a d l i m i t a t i o n s . 7.4.2.3 Wide span s t r u c t u r e s ; i.e., verylargepipes,arches, and wide box culverts, even with substantial cover w i l l t e n d t o accunulate stress from surface loads (by s o i l arching) and may have t o s u p p o r t v i r t u a l l y a l l of t h e a i r c r a f t ( l i v e ) l o a d as well a8 the earth (dead) load. Thus any s t r u c t u r e whose span exceeds about one-third o f the cover depth should be c a r e f u l l y a n a l y e e d t o e s t a b l i s h s u r f a c e l o a d l i m i t 8 or p o s s i b l e n e e d f o r s trengthening.

*

Consider a l l wheels within or touching a circle whose diameter equals the depth of p r o t e c t i v e c o v e r over t h e s t r u c t u r e .

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S h a l l po iwpceos ,n d u istus b , d r a i ancnsu,dl v e r t s

7.4.3.1 The ACN-PCN method limits a i r c r a f t mass t op r e v e n ot v e r - s t r e s so tf h e pavementsubgradeandoverlyinglayers.These same limits t e n d t o p r o t e c t s h a l l o w buried structures from over-stress, except for quite large (over 3 o r 4 m diameter or s p a n ) s t r u c t u r e s , w h i c h may accumulate load on t h e same c r i t i c a l s e c t i o n f r o m more t h a n a minimum c o v e r of about one-half metre one landing gear leg. Beneath rigid pavements between the slab and structure i s commonly c o n s i d e r e d t o p r o v i d e a d e q u a t e p r o t e c t i o n w i l l b e p r o t e c t e d when from any loading. Pipes and culverts beneath flexible pavements i s within about one-half metre of t h e t o p o f t h e their top surface (outer crown of pipe) subgrade. A t g r e a t e r d e p t h s , w h i l e stresses f r o m s u r f a c e w h e e l l o a d s o r combined e f f e c t s of s e v e r a l w h e e l l o a d s a t t e n u a t e a n d are less t h a n t h e pavement subgrade can a c c e p t , t h e combined e f f e c t ( s t r e s s ) a n d f o r a n a i r c r a f t m u l t i p l e w h e e l l o a d , t h o u g h ACN-PCN l i m i t e d , may b e g r e a t e r t h a n were c o n s i d e r e d in t h e o r i g i n a l pavement design. etc., s h o u l d b e c a r e f u l l y e x a m i n e d f o r p o s s i b l e n e e d Therefore pipes, drains, culverts, for s t r e n g t h e n i n g when t h e i n d i v i d u a l w h e e l l o a d o r t h e number of wheels of t h e u s i n g aircraft are expected to be increased. 7.4.3.2

3 o r 4 m) w i l l n e e da n a l y s i s S h a l l o ws t r u c t u r e so fs u b s t a n t i a sl p a n( o v e r i n wheel loads or gross aircraft masses.

in connexion with any contemplated increases 7.4.4

A t surfad c er a i ncso, n d u i tasnt, hldiek e

etc.), 7.4.4.1 C o l l e c t odr r a i n s , box c o n d u i t(sf olri g h t i n gw , i r i n gf,u elli n e s , and any similar pavement c r o s s i n g i n s t a l l a t i o n s , are s o m e t i m e s p l a c e d d i r e c t l y a t t h e pavement surface. These would rarely be so l a r g e t h a t more t h a n a s i n g l e w h e e l would need t o b e s u p p o r t e d by t h e i n s t a l l a t i o n a t any time. Consequently, only single wheel as well a s e v a l u a t i o n . loadings need be of c o n c e r n f o r t h e d e s i g n 7.4.5

Bridges supporting aerodrome pavements

7.4.5.1 Need f o rp a s s a g e of highway and r a i l trafficbeneathaerodromepavements and t h e p l a c e m e n t o f t e r m i n a l c o n n e x i o n s a n d f a c i l i t i e s b e n e a t h t a x i w a y a n d a p r o n pavem e n t sh a sr e q u i r e dt n eu s eo fb r i d g e st os u p p o r tt h ep a v e m e n t sa n du s i n ga i r c r a f t . Such s t r u c t u r e s r e c e i v e l i t t l e i f any protection from pavement load limitations and must be separatelyconsideredinestablishingsafeloadings. The o r i g i n a l d e s i g n a n a l y s e s w i l l h a v ee s t a b l i s h e dt h et y p ea n dm a g n i t u d eo fl o a d sf o rw h i c ht h eb r i d g e s are adequate. If the intended usage has changed and paveaents are l i k e l y t o b e u s e d by markedly heavier aircraft or aircraft with different undercarriage configuration than considered in d e s i g n , a new a n a l y s i s w i l l be needed t o e s t a b l i s h t h e s u i t a b i l i t y of t h e s t r u c t u r e f o r such usage. 7.4.6

su P pi lpeos tr rt u ed ctures

7.4.6.1 Sometimes runways and taxiways extend over water a n dt h e s ea r ep l a c e d on p i l es u p p o r t e ds t r u c t u r e s .T h e s e , as f o r b r i d g e s , w i l l h a v e b e e n s u b j e c t t o d e s i g n Here a g a i n t h e r e w i l l be a need f o r analysestoprovideforthecontemplatedloads. r e a n a l y s i s if o p e r a t i o n s by h e a v i e r a i r c r a f t o r a i r c r a f t w i t h s u b s t a n t i a l l y d i f f e r e n t u n d e r c a r r i a g e l a y o u t are contemplated. 7.4.7

Tunnels pavements under

in a manner similar t o l a r g ed i a m e t e p r i p e sa n dc a nb e 7.4.7.1 Tunnels behave c o n s i d e r e d t o r e s p o n d i n much t h e samemanner. Thus s h a l l o w e r t u n n e l s w o u l d r e q u i r e

ICAO 9157 P A R T * 3

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W YBY1Y1b 0019610 T Y 9

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careful analysis of expected increased aircraft loads on overlyingpavements.Deeply buried tunnels might require only casual examination i f cover depths were s u f f i c i e n t t o minimize induced l i v e l o a d s . 7.4.8

y iting Treatment of s e v e r el ilm

cases

7.4.8.1 Where s t r u c t u r ebs e n e a t hp a v e m e n tlsi m iat i r c r a flto a d s beyond t h e PCN (which i s a s s e s s e d t o p r o t e c t t h e pavement) t h e s e l i m i t a t i o n s w i l l need t o be r e p o r t e d i n terms of s p e c i f i c a i r c r a f t t y p e andload (mass) as exceptions. Where m u l t i p l e t a x i ways permit avoidance of t h e c r i t i c a l s t r u c t u r e s t h e p r o b l e m c a n b e h a n d l e d by l o c a l If, however, a l l a i r c r a f t r m s t c r o s s t h e critical structurethe r o u t i n go fa i r c r a f t . l i m i t a t i o n mustbeemphasized when r e p o r t i n g pavement s t r e n g t h s . Only v e r y shallow s t r u c t u r e s a n d extreme overloading e x c e p t f o r b r i d g e s o r p i l e s u p p o r t e d pavements r e p r e s e n t some h a z a r d t o a i r c r a f t , a n d a i r c r a f t s a f e t y w i l l r a r e l y i f e v e r b e compromised by overload of b u r i e d ( e a r t h c o v e r e d ) s t r u c t u r e s . B r i d g e s a n d p i l e s u p p o r t e d p a v e uust b e s t r u c t u r a l l y c a p a b l e of s u p p o r t i n g t h e ments receive the loading dkrectly and imposed loadings.

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7.4.8.2 Load l i m i t a t t o n so n critical S t r u c t u r e sc a nb e l i m i n a t e de i t h e br y special analyses which establish that larger than intended design loadings can be s u s t a i n e d ,o r by s t r e n g t h e n i n g . Commonly, designconservatism,better-than-minimrn i n s t a l l a t i o n , l a r g e r - t h a n - n e e d e d e a f e t y E a c t o r s a n d more s e a r c h i n g d e s i g n t y p e a n a l y s e s may r e s u l t i n l a r g e r a l l o w a b l e l o a d i n g s . T h e s e can rangefrom a simple r e s t u d y of the d e s i g n d a t a t o e x t e n s i v e f i e l d s t u d y of t h e i n s t a l l a t i o n i n c l u d i n g s t u d y o f s u r r o u n d i n g b a c k f i l l o r measurementof s t r a i n o r d e f l e x i o n r e s p o n s e of t h e s t r u c t u r e u n d e r l o a d . An exanple o€ s u c h a study can be found i n t h e A p r i l 1 9 7 3 i s s u e o f A i r p o r t World u n d e r t h e t i t l e , "New Bridgeor No?". This is a p u b l i c a t i o n o f t h e U n i t e d S t a t e s Aircraft Owners a n d P i l o t s A s s o c i a t i o n a n d t h e a r t i c l e d e a l s w i t h a s t u d y u n d e r t a k e n i n t h e 1970s t o a s s e s s t h e s u i t a b i l i t y of a n e x i s t i n g b r i d g e a t Chicago O'Hare I n t e r n a t i o n a l A i r p o r t f o r u s e by w i d e b o d i e d a i r c r a f t .

7.4.8.3 The s t r e n g t h e n i n go f a s u b s t r u c t u r ec a nb ea c c o m p l i s h e du s i n gi n t e r n a l bands, struts, o r l i n e r s t o s t r e n g t h e n o r r e d u c e s p a n i n p i p e s , c u l v e r t s , a r c h e s , etc., b u tt h e s e r e d u c e t h ed e s i g n e dd r a i n a g ec a p a c i t y . Sometimes s t r u c t u r e s c a n b e s t i f f e n e d by g r o u t i n g s u r r o u n d i n g s o i l f r o m t h e s u r f a c e o r f r o m i n s i d e t h e s t r u c t u r e . It may be p o s s i b l e t o introduce compressible zones of s o i l o r o t h e r material a b o v e p i p e s o r c u l verts andreducethetransmissionof pavement l o a d s t o t h e b u r i e d s t r u c t u r e . Also, p r o v i s i o n of l o a d d i s t r i b u t i n g pavement s t r u c t u r e s ( b u r i e d s l a b s f o r i n s t a n c e ) may reduceloads on p i p e s , c u l v e r t s o r d r a i n s . Of c o u r s e , r e d e s i g n a n d r e c o n s t r u c t i o n is theobviousultimatesolution. Some b r i d g e s o r pile-supportedpavements may be s t r e n g t h e n e d by adding elements (beams, etc.) t o t h e e x i s t i n g s t r u c t u r e . 7.5

Considerations i n d e s i g n of new f a c i l i t i e s

7.5.1 S t r u c t u r aclo n c e r n€sodrr a i n a gaen d similar s t r u c t u r e is nr e l a t i o nt ot h e e v a l u a t i o n of pavements f o r l o a d s u p p o r t c a p a c i t y h a v e b e e n d i s c u s s e d earlier i n t h i s c h a p t e r .P a t t e r n s of behaviour in c o n n e r d o n w i t h s i z e , f l e x i b i l i t y , l i v e a n d d e a d loads, deep and shallw cover have been indicated, and these apply also to design considerations where new f a c i l i t i e s are p l a n n e d , T h i s s e c t i o n will amplify EO= of t h e earlier d i s c u s s i o n s a n d treat a s p e c t s of s t r u c t u r a l b e h a v i o u r o f somewhat nore d i r e c t concern for design.

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7.5.2 Loads. Loads which those resulting from the weight

i I

m e t be c o n s i d e r e idd nesign of b u r i e sdt r u c t u r e 6 are of o v e r l y i n g s o i l and pavement s t r u c t u r e ( o v e r b u r d e n )

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p l u s t h o s e i n d u c e d by a i r c r a f t o r o t h e r v e h i c l e s on t h e pavementabove. Heavy construci t h a s i t s f u l l p r o t e c t i v e c o v e r may a l s o need t o be tion loads passing over pipe before considered.Theseloadsproducethepatternsofambient stress p r e s e n t i n embankments by t h e where they are n o t d i s r u p t e d by t h e p r e s e n c e of p i p e o r o t h e r s t r u c t u r e s o r p o c k e t s of l o o s e , d e n s e o r o t h e r t y p e s o f s o i l i n t r o d u c e d by t h e i n s t a l l a t i o n of pipes, c u l v e r t s , etc. It i s t h e d i s t o r t i o n of theambient stress p a t t e r n s by t h e c h a r a c t e r o f the pipe o r structure, the nature of the pipe bedding, any trench used during installat i o n , and the type and compacted density of t h e b a c k f i l l a r o u n d t h e p i p e w h i c h l e a d s t o l a r g e r o r smaller than ambient stress l o a d s o n t h e b u r i e d s t r u c t u r e s . T h i s t o o i s what complicates the design problem and leads to established design methods which provide only nominal guidance. 7.5.3 Ambient ovsrburden stresses are t h er e s u l t of t h e mass oof v e r l y i n g soil andpavement s t r u c t u r e a n d c a n b e d i r e c t l y d e t e r m i n e d . S t r e s s e s i n d u c e d by a i r c r a f t tire loads can be calculated using the theory for a uniformly distributed circular load on t h e s u r f a c e o f a continuum. The t h e o r y f o r a n elastic l a y e r e d c o n t i n u u m , w i t h s u i t a b l e e l a s t i c c o n s t a n t s (E, p), s h o u l d b e p r e f e r r e d , b u t t h e t h e o r y f o r a single layer system (Boussinesq) w i l l p r o v i d e r e a s o n a b l e stress d e t e r m i n a t i o n s f o r f l e x i b l e p a v e m e n t s anddeeperinstallationsbeneathrigid pavements. Plotsortabulationsofsinglelayer stresses canbefound i n r e f e r e n c e s s u c h as: t h e 1954 Highway Research Board Pavement Proceedings, HRB B u l l e t i n 342 of 1962,Yoder'stextbookon"Principlesof Design" (United States), Croney's text "The Design andPerformance of Road Pavements" TRRL (United Kingdom). S t r e s s e s f o r t h e combined e f f e c t s of s e v e r a l w h e e l s c a n b e d e t e r d n e d by s u p e r p o s i t i o n o f t h e s i n g l e w h e e l stresses a t p e r t i n e n t l a t e r a l s p a c i n g s . time rate o f r e s p o n s e o f s o i l t o r a p i d l o a d i n g it i s not necessary to Because of the consider any added dynamic effects of t h e a i r c r a f t l o a d i n g .

7.5.4 The ambient stresses w h i c oh b t a i n a t t hve a r i o uds e p t hbs e n e a t thhpe a v e ment are t h u s a combination of t h e o v e r b u r d e n ( d e a d l o a d ) stresses a n d t h e a i r c r a f t l a n d i n gg e a rl o a d( l i v el o a d ) stresses. It i s t h e s e stresses modified by t h e e x i s t e n c e and behaviour of a p i p e or o t h e r b u r i e d s t r u c t u r e a n d a n y d i s t o r t i o n s d u e t o its installation that determine the loads which mst b e s u p p o r t e d by t h e p i p e o r s t r u c t u r e . In general, hard (stiff) elements or zones w i l l a c c u m l a t e stress f r o m t h e a d j a c e n t w i l l s h e d stress t o t h e a d j a c e n t s o i l . embankment s o i l w h i l e s o f t e l e m e n t s o r z o n e s will Thus t h e more r i g i d s t r u c t u r e s , s u c h as box c u l v e r t s , c o n c r e t e p i p e , a n d t h e l i k e , tend to be subject to greater stress a n d l o a d t h a n t h a t i m p l i e d by the ambient stress, w h i l e more f l e x i b l e s t r u c t u r e s , s u c h a s steel, aluminium,and plastic pipe or rigid structuresprovidedwithanoverlyingzoneofloose s o i l , straw, sawdust, etc. w i l l t e n d t o b e s u b j e c t t o less t h a n t h e a m b i e n t stress. 7.5.5 A most i m p o r t a ncto n s i d e r a t i o intnhde e t e r m i n a t i o onlfo a d i n gfsodr e s i g n of b u r i e d s t r u c t u r e s is i n p r o v i d i n g f o r f u t u r e u p g r a d i n g ofpavement f a c i l i t i e s and growth i n a i r c r a f t masses supported. Where upgrading i s l i k e l y i n t h e f u t u r e t h e d e s i g n of b u r i e d s t r u c t u r e s b e n e a t h p a v e m e n t s f o r t h e h e a v i e r l o a d i n g s e x p e c t e d w i l l commonly be f a r less c o s t l y d u r i n g t h e o r i g i n a l d e s i g n a n d c o n s t r u c t i o n t h a n when l e f t f o r subseq u e n t modif i c a t i o n .

7.5.6 Pipes. Pipes are d e s c r i b e gd e n e r a l l iyn 7.2.1 and most types are covered by ASTM s t a n d a r d s f o r t h e p i p e c h a r a c t e r i s t i c s a n d tests t o d e t e r m i n e p i p e s t r e n g t h . Concrete,clay,asbestos-cement,solid w a l l plastic, and other geometrically similar t y p e s of p i p e are made in a v a r i e t y of w a l l t h i c k n e s s e s a n d / o r r e i n f o r c e m e n t s , as w e l l as d i a m e t e r s t o p r o v i d e a n a r r a y of s t r e n g t h s f o r u s e i n d e s i g n of i n s t a l l a t i o n s . S t e e l , aluminium,and s o w p l a s t i c p i p e s a r e made in a v a r i e t y of gauges (thicknesses of material) a n d c o r r u g a t i o n c o n f i g u r a t i o n s t o p r o v i d e a n a r r a y of p i p e s t i f f n e s s e s and

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are most common side-wall strengths for installation design purposes. While round pipes t h e r e are e l l i p t i c a l p i p e s u s e d v e r t i c a l l y f o r i n c r e a s e d s t r e n g t h or h o r i z o n t a l l y f o r o lw head and pipe arches having rounded crown and f l a t t e n e d i n v e r t f o r s p e c i a l a p p l i c a t i o n as access ways, u t i l i t y d u c t s , etc.

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7.5.7 Design l i m i t a t i o n s for r i g i dp i p e are commonly e s t a b l i s h e dt oc o n t r otlh e progression of cracking a t t h e crown and invert. Prevention of cracks wider than 0.4 m is the usual practice. Earlier practice for flexible pipe installation design was t o limit p i p e d e f l e c t i o n t o 5 per cent of the pipe diameter, but current practice prefers t o r e q u i r e competent b a c k f i l l s o i l compaction (85 p e r c e n t of StandardDensity ASTM D-698) and limit t h e b u c k l i n g i n r i n g c o n p r e s s i o n .

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7.5.8 I n s t a l l a t i ocno n d i t i o n e . Bedding, b a c k f i l l , and trench conditions of p i p e installation can have simificant effect on performance. Pipe can be placed on f l a t compacted e a r t h , on a 60', goo, o r 120' shapedbed,on a sand or f i n e g r a v e l c u s h i o n , I n a lean or coupetent concrete cradle, etc. Pipe can be placed i n a narrow o r wide trench, shallow or deep trench, vertical o r sloping sidewall trench, o r no trench. B a c k f i l l c a n be poorly compacted beneath (haunches) or beside the pipe and can be the same as adjacent embankment material o r a select sand, gravel, or other superior material, o r i t canbe a s t a b i l i z e d (cement o r lime) soil. Mgid pipe can be i n s u l a t e d Prom i t s normal a c c u w l a t i o n of g r e a t e r t h a n a m b i e n t s t r e s s by placing a s o f t zoneof l o o s e s o i l , straw, foamed p l a s t i c , l e a v e s , o r e i m i l a r m a t e r i a l above the pipe. A11 of t h e s e many variables can have an impact on t h e d e s i g n l o a d s t o be Considered. 7.5.9 Design. Because of t h e many v a r i a b l eilsno a d i n gp,i pceh a r a c t e r i s t i c s , and installation conditions design concepts, methods, and supporting methods f o r c h a r a cterizing behaviour of materials are beyondwhat can be presented here. Design details can be found i n some geotechnical textbooks, such as "Soil Mechanics" by Krynine (United S t a t e s ) , "Soil Engineering" by Spangler (United States) and in trade literature, such a6 "Concrete Pipe Design Manual" o f t h e American Concrete Pipe Association (United States Library ofCongress Catalog No. 78-586241, "Handbook of Steel Drainageand Highway Construction Products" of the American Iron and Steel I n s t i t u t e ( U n i t e d S t a t e s Library of Congress Catalog NO. 78-174344) and in t h e many references t o t e c h n i c a l l i t e r a t u r e c o n t a i n e d i n t h e s e documents. Some s p e c i f i c d e s i g n g u i d a n c e f o r minirmm protective cover beneath flexible or r i g i d pavement f o r s e v e r a l t y p e s of pipe precomputed based on selected (common) i n s t a l l a t i o n c o n d i t i o n s c a n be found i n t h e U n i t e d S t a t e s F M manualon "Airport Drainage" AC 150/5320-%, as w e l l as i n t h e two t r a d e l i t e r a t u r e manuals referenced above. 7.5.10 Other structures. Design of bridges and pile supported extensions over water, w h i c h s u p p o r t a i r c r a f t l o a d s d i r e c t l y , rmst f o l l o w a c c e p t e d s t r u c t u r a l d e s i g n practice. It w i l l be most important t o a n t i c i p a t e f u t u r e a i r c r a f t growth l o a d s t o a v o i d very costly subsequent strengthening. Box c u l v e r t s w i l l be s u b j e c t t o t h e a m b i e n t stresses (7.5.3) increased by t h e u p t h r u s t of s u c h s t i f f s t r u c t u r e s i n t o t h e o v e r l y i n g embankment (7.5.4). The resulting load should be determined by c a r e f u l a n a l y s i s , b u t should f a l l between about 130 per cent and 170 per cent of t h e l o a d due only to ambient stress depending upon span of t h e s t r u c t u r e , magnitude and extent of surface load, p r o t e c t i v ec o v e rd e p t h ,a n ds o i ls t i f f n e s sa d j a c e n tt ot h ec u l v e r t . Any large corrugated metal arches (over 5 m) w i t h s h a l l m s o i l c o v e r s h o u l d b e s u b j e c t e d t o c a r e f u l geotechnical and structural design. Each w i l l be a s e p a r a t e case and of a magnitude t o warrant careful design analysis.

I C A O 9357 P A R T S 3

CHAPTER 8.

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CONSTRUCTION OF ASPHALTIC OVERLAYS

8.1Introduction

8.1.1 The volume and frequency of operations at many airports makes it virtually mandatory to overlay (resurface) runways portion by portion so that they may be returned to operational status during peak hours. The purpose of this chapter to is detail the procedures to be used by those associated with such overlaying, viz. the airport manage project manager, designer and contractors to ensure that the work is carried out mogt efficiently and without loss of revenues,-inconvenience to passengers or delays to the air traffic systems. A unique feature of such off-peak construction is that a temporary ramp (a transition surface between the overlay and the existing pavement) must be constarct at the end of each work session so that the runway can be used for aircraft operations once the work force clears the area. This chapter includes guidance on the design of such temporary ramps, however, it not is the intent of this chapter to deal with the design of overlays per se. For guidance on the latter subject, the reader should refer to Chapter 4. 8.2 Airport authority’s role

Project co-ordination 8.2.1

‘0

8.2.1.1 Off-peak construction is, by its very nature, a highly visible project requiring close co-ordination with all elements of the airport during planning and de and virtually daily during construction. Once a runway paving project has been identifi by the airport, it is important that the nominees of the airport authority, users and Civil Aviation Authority of the State meet to discuss the in which mannerconstruction is to be implemented. The following key personnel should bein attendance at all planning meetings: from. the airport authority - the project manager, the operations, planning, engineering and maintenance directors; from the airlines - local station managers and head office representatives where appropriate; from the civil aviation authority representatives from Air Traffic Services and Aeronautical Information’Services. The agenda should include:

a)

determination of working hours. Since time is of the essence in off-peak construction, the contractor should be given as much time as possible to overlay the pavement each work period. A minimum period of 88 hours is recommended. Work should be scheduled for a time period that will displace the least amount of scheduled flights. The selection of a specific time period should be developed and co-ordinated with airline and other representatives during the initial planning meetings. Early identification of the hours will allow the airlines to adjust future schedules, as needed, to meet construction demands. It is essential that the runway be opened and closed at the designated time without exception, as airline flight schedules, as well as the contractor’s schedules, will be predicated on the availability of the runway at the designated time;

b)

identification of operational factors during construction and establishment of acceptable criteria include: 1)

designation of work areas;

2)

aircraft operations;

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affected navigation aids (visual and non-visual aids);

4) security requirements and truck haul routes;

8.2.2

5)

inspection and requirements to open the area €or operational use;

6)

placement and removalof construction barricades;

7)

temporary aerodrome pavement marking and signing;

8)

anticipated days of the week that construction will take place; and

9)

issuance of NOTAM and advisories;

c)

lines of communication and co-ordination elements. isItessential that the project manager be the only person to conduct co-ordination of the of communication should be pavement project. The methods and lines discussed for determining the availability of the runway at of the start each work period and the condition of the runway prior to opening it for operations;

d)

ramps and other special aspectsof construction including temporary details as described herein; and

e)

contingency plan in case of abnormal failure or an unexpected disaster.

Role of project manager

8.2.2.1 Project manager. It is essential that the airport authority select a qualified project manager to oversee all of phases the project, from planning through in design final inspectionof the completed work.This individual should be experienced and management of aerodrome pavement construction projects and bewith familiar the operation of the airport. The project manager should be the final authority on all technical aspectsof the project and be responsible for its co-ordination with airport operations. All contact with any element of the airport authority should be made only by the project manager so as to ensure continuity and proper co-ordination with all elements of aerodrome operations. Responsibilities should include: a)

planning and design: 1)

establishment of clear and concise lines of communications;

2)

participation as a member of the design engineer's selection team;

3)

co-ordination of project design to meet applicable budget constraints;

4) co-ordination of airport and airlines with regards to design review, including designated working hours, aircraft operational requirements, technical review and establishment of procedures for co-ordinating all work; and 5)

b)

chairmanship of all meetings pertaining, to the project; and

construction: 1)

complete management of construction with adequate number of inspectors to observe and document work by the contractor;

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2)

checking with the weather bureau, airport operations and air traffic control prior to starting construction and confirming with the contractor's superintendent to verify if weather and air traffic conditions will allow work to proceed as scheduled;

3)

conferring with the contractor's project superintendent daily and agreeing on how much work to attempt, to ensure the opening of the runway promptly at the specified time each morning. This is especially applicable in areas where pavement repair and replacement are to take place; and

4) conducting an inspection with airport operations of the work area before opening itto aircraft traffic to ensure that all pavement surfaces have been swept clean, temporary ramps are properly constructed and marking is available for aircraft to operate safely. 8.2.2.2 Resident engineer. The designation of a resident engineer, preferably a civil engineer, will be of great benefit to the project, and of great project manager. Duties of the resident engineer should include:

assistance

a)

preparation of documentation on the work executed during each work period;

b)

ensuring all tests are performed and results obtained from each work period;

to

c) scheduling of inspectionto occur each work period; d)

observing contract specifications compliance and reporting of any discrepancies to the project manager and the contractor; and

e) maintaining a construction diary. 8.2.3

Testing requirements

8.2.3.1 There is no requirement for additional tests for off-peak construction versus conventional construction. The only difference with off-peak construction is that it requires acceptance testing to be performed at the completion of each work period and prior to opening to operations and results reviewed before beginning work again. These procedures normally will require additional personnel to ensure that tests are performe correctly andon time. 8.2.4

Inspection requirements

8.2.4.1 One of the most important aspects of successful completion of any kind of paving project is the amount and quality of inspection performed. Since the airport accepts beneficial occupancy each time the runway istoopen traffic, acceptance testing must take place each work period. In addition to the project manager and resident engineer, the following personnel are recommended as a minimum to observe compliance specifications:

a)

Asphalt plant inspector. A plant inspector with a helper whose primary duty it will be to perform quality control tests, including aggregate gradation, hot bin samples and Marshall tests.

b)

Paving inspectors. There should be two paving inspectors with each paving machine. Their duties should include collection of delivery . tickets, checking temperatures of delivered material, inspection of

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grade control methods, and inspection of asphalt lay-down techniques and joint construction smoothness. Compaction inspector. The compaction inspector should be responsible for observing proper sequencing of rollers andfor working witha field density meter to provide the contractor with optimum compaction information. Survey crew. Finished grade information from each work period is essential to ensuring a quality job. An independent registered surveyor and crew should record levels of the completed pavement at of intervals at least8 m longitudinally and4 q transversely, and report the results to the project manager at the completion of each work period. Pavement repair inspector. Shallbe responsible for inspectionof all pavement repairs and surface preparation prior to paving. Electrical inspector. Ensures compliance with specifications. 8.3 Design considerations 8.3.1General.Plansandspecificationsforpavementrepairandoverlayduring of the off-peak periods should be presented in such detail as to allov ready determination limits of pavement repair, finish grades and depths of overlay. Plans and specifications are to be used for each work period by the contractor and inspection personnel, be clear and precise in every detail.

and

should

Pavement 8.3.2 survey 8.3.2.1 A complete system of bench marks should be seton the side of the runway or taxiway to permit a ready reference during cross-sectioning operations. The marks bench should be set at approximately 125 m intervals. Pavement cross-sectioning should be performed at 8 intervals longitudinally, and 4 intervals transversely. Extreme care should be exercised in level operations, since the elevations toare be usedin determining the depth of asphalt overlay. The designer should not consider utilizing grade information from previous as-built drawings or surveys that run during were the winter months,as it has been shohn that elevations can vary f r m one season to the next. This is especially critical for single lift asphalt overlays. 8.3.2.2 After finish grades and transverse slope of the runway are determined, a tabulation of grades should be included in the plans for the contractor to use in bidding the project and for establishment of erected stringline. The tabulation of grades should include a column showing existing runway elevation, a column showing finish overlay grade, and a column showing depth of overlay. Grades shouldbe shown longitudinally every 8m and transversely every 4 m. This item is considered essential in the preparation of plans for contracting off-peak construction. 8.3.3

Special details

8.3.3.1 Details pertaining a)

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to the following items should be included in the plans:

of each hot mix asphalt concrete overlay Temporary ramps. At the end work period, it will be necessary to construct a ramp to provide a transition from the new course of overlay to the existing pavement. The only exceptionto construction of a ramp is when the depth of the overlay is 4 cm or less. In multiple lift overlays, these transitions should be not closer than q150 to one another. As far as possible, the overlay should proceed from one ofend the runway toward the other end in the same direction as predominant aircraft operations so that most aircraft encountera downward ramp slope. In the event of continued

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T x 100 cm t o 125 cm

Transition

4 T

Overlay

I

2 X A

I

Exis tine grade line

Heel C u t

T

Illustration a)

2nd n i g h to v e r l a y

=

.~

Thickness of o v e r l a y ( i n

cm)

1st n i g h to v e r l a y

++

I

Heel Cut

2 X A

herlay

7Transition to pilna c e

1

4 T

i

remain

A

E x i s t i n g r a d lei n e / = M a x i m s i z e of aggregate

Illustration b ) Figure 8-1.

t-

Temporary ramp constructionwithcoldplaning

T x 100 cm t o 125 cm

Remove e n t i r e transition prior t o s t a r t of-work /

1

.

Figure 8-2.

I

4

T

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\

machine

f

Rake o u t l a r g e s t o n e and compact edge

T

Thickness of overlay (in cm)

Temporary ramp c o n s t r u c t i o n without coldplaning

machine

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Design

Aerodrome

advantageous for the operational change of direction, it be would overlaying to proceed upgrade since an upgrade ramp is shorter and avoids long thin tapers. The construction of the ramp is one of the most important features in the work period. A ramp that is too steep could cause possible structural damage to the operating aircraft or malfunction of the aircraft's instruments. A ramp thatis too long may result in a ravelling of the pavement, and foreign object damage to aircraft engines, as well as taking excessive time to construct. The longitudinal slope of the temporary ramp shall be 0 between . 8 and 1.0 per cent, measured with reference to the existing runway surface or previous overlaycourse. The entire widthof the runway should normally be overlaid during each work session. Exceptional circumstances, e.g. adverse weather conditions, equipment failure, etc. may not permit the overlaying of the full runway width during a work session. Should merged that be the case, the edges be need to with the old pavement surface to avoid a sudden level change in the event an aircraft veers off the overlaid portion. The maximum transverse slope of the temporary ramp should not exceed 2 per cent. A temporary ramp may be constructed in two ways, depending upon the type of equipment that is available. The most efficient way is to utilize a cold planing machine to heel-cut the pavement at the beginningat and the endof the work period overlay (refer to Figure8-1). If cold planing equipment is not available, then be constructed as shown in Figure 8-2. In no a temporary ramp should case should a bond-breaking layer be placed under the ramp for easy removal during the next work period. Experience has shown that this bond-breaking layer almost always comes loose causing subsequent breaking-up of the pavement under aircraft operations. b)

In-pavement lighting. Details depicting the removal and re-installation of in-pavement lighting are betoincluded on the plans where applicable. The details should depict the removal of the light fixture plate over the light base, and extension ring, placementa target of filling the hole with hot mix dense graded asphalt until overlay survey location information, core operations are complete, accurate drilling with 10 a cm coreto locate the centre of the target plate, and final coring with an appropriate sized core machine. The light and new extension ring can then be installed to the proper elevation.

c) Runway markings. During the courseof off-peak construction of a runway overlay, it has been found acceptable, if properly covered by a NOTAH, to mark only the centre line stripes and the runway designation numbers on the new pavement until the final asphalt lift has been completed and some final striping can then be performed. Incases where cold planing of the surface or multiple lift overlays are R Sused, many as three consecutive centre line stripes may be omitted to enhance the bond between layers.

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APPENDIX 1 AIRCRAFT CHARACTERISTrCS AFFECTING PAVEMENT BEARING STRENGTH 1. G e n e r a l 1.1 T hA i sp p e n d d i xe s c r i b tehs o c s eh a r a c t e r i s t i a o c isfr c r aw f th i cahf f e c t pavement s t r e n g t h d e s i g n , n a m e l y : a i r c r a f t w e i g h t , p e r c e n t a g e l o a d on nosewheel, wheelarrangement, m i n l e g l o a d , tire p r e s s u r e and c o n t a c t area ofeach t i r e . T a b l e Al-1 c o n t a i n s t h e s e d a t a f o r m o s t o f t h e commonly u s e d a i r c r a f t . 1.2 A i r c r a lfot a d s are t r a n s m i t t ettdoh e pavement through the landing gear whichnormallyconsistsof two main l e g s a n d a n a u x i l i a r y l e g , t h e latter being either nearthenose (now t h e m o s t f r e q u e n t a r r a n g e m e n t ) o r n e a r t h e t a i l ( o l d e rs y s t e m ) .

1.3 The p o r t i oontfhleo aidm p o s ebdeya clhe g w i l l d e p e nodtnhpeo s i t i o n o ft h ec e n t r e of g r a v i t y w i t h r e f e r e n c e t o t h e t h r e e s u p p o r t i n g p o i n t s . The s t a t i c d i s t r i b u t i o n of t h e l o a d b y t h e d i f f e r e n t l e g s o f a common t r i c y c l e l a n d i n g g e a r may b e i l l u s t r a t e d as f o l l o w s :

A L1

t:

CG 9 L2 r

.

1 )

Where W i s t h e a i r c r a f t w e i g h t ; P 1 t h e l o a d t r a n s m i t t e d b y t h e a u x i l i a r y l e g ; €9 t h e L 1 and L2 t h e d i s t a n c e m e a s u r e d a l o n g t h e p l a n e l o a d t r a n s m i t t e d by b o t h m a i n l e g s ; of symmetryfrom t h e c e n t r e o f g r a v i t y t o P 1 a n d P2 r e s p e c t i v e l y , t h e n

T h e r eofr e

P2 = P I

L1 2

3-239

Aerodrome Design Manual

3-240

L l / L 2 i s around 9, i . e . t haeu x i l i a rlyeagc c o u n t s 1 .U 4 s u a l ltyhrea t i o f o ra p p r o x i m a t e l y1 0p e rc e n to ft h ea i r c r a f tg r o s sw e i g h t .T h e r e f o r e ,e a c h main 45 p e r c e n t of t h a t w e i g h t . Wheel b a s e and t r a c k l e g imposes a l o a d e q u a l t o a b o u t i s no widthhavenotbeenincluded,sincethesedimensionsaresuchthatthere stresses imposedby t h e d i f f e r e n t l e g s of t h e p o s s i b i l i t y of i n t e r a c t i o n o f t h e landinggear. 1.5 From t h e above considerations, it w i l l b e seen t h at thceh a r a c t e r i s t i c s pavement s t r e n g t h of each main l e g p r o v i d e s u f f i c i e n t i n f o r m a t i o n f o r a s s e s s i n g i t s e l f t op r o v i d i n gd a t at h e r e o n . r e q u i r e m e n t s .A c c o r d i n g l y ,t h et a b l ec o n f i n e s 136 The l o asdu p p o r t ebdeya clhe g i s t r a n s m i t t e tdtoh e pavement by one or several. rubber-tired wheels. The followingwheelarrangements w i l l befoundon c i v i l a i r c r a f t a t p r e s e n t i n service. t h e main l e g s o f l a n d i n g g e a r o f

0 Single

Dud

1.7 F op ra v e m e d n et s i gannedv a l u a t i opnu r p o s et hsf d e l o w i nwgh e sepl a c i n g s a r e s i g n i f i c a n t , and t h e r e f o r e l i s t e d i n t h e t a b l e . S

- distance between centres of contact

ST

- distance between

SD

- distance between centres

areas of dual wheels

axis of tandem wheels of c o n t a c t areas of diagonal wheels and

i s given by the expression

= Tire p r e s s u r e s g i v e n

J?s2

2 + ST>

are i n t e r n a l , o r i n f l a t i o n p r e s s u r e s .

It s h o u l d ' bneo t etdh at ht r o u g h o ut htt ea b lfei g u r er se f ettorh e lesser o p e r a t i o n a l w e i g h t s , f i g u r e s a i r c r a f t a t i t s maximum take-offweight.For quoted for "load on each leg'', "tire-pressure" and/or "contact area" should be decreased proportionally.

1.8

31/8/89 No. 2

I C A O 9157 P A R T S 3 P a r t 3.-

ft

4A414Lb 0037623 8 2 4 3-241

Pavements

L i s t of a b b r e v i a t i o n s used in Table Al-1

C9M

- Complex

P

- Dud - Dual tandem - Front

R

- Rear

D

DT

S

SD

ST T kg MPa cm

- Distance - Distance - Distance

between c e n t r e s of contact areas of dualwheels between c e n t r e s of c o n t a c t a r e a s

of diagonalwheels

between a x i s of tandem wheels

- Tandem - Kilogram - Megapascal - Centimetre

Note on u n i t s T h i s t a b l eh a s beenprepared m u l t i p l y by 9.80665.

i n metric u n i t s .

To convert from kilogramto

newton

31/8/89 No. 2

Table Al-1.-

Aircraft characteristics for design and evaluation of pavements

A300 B2 Airbus

137 000

47.0

DT

64 390

1.2

89

165.9

A300 B2 Airbus

142 000

47.0

DT

66 740

1.23

8P

165.9

A300 R4 Airbus

150 000

47.0

PT

70 500

1.39

93

168.1

A300 B4 Airbus

157 000

47.0

DT

73 790

I .48

93

168.1

A300 R4 Airbus

165 000

47.0

PT

77 550

1.29

93

I6P. 1

A30&600 Airbus

165 000

47.0

PT

77 550

1.29

93

168.1

A300-600R Airbus

170 000

47.4

DT

80 580

1.35

93

168. I

A300-600R Airbus

171 700

47.4

DT

81 390

1.35

03

16P. 1

A310-200 Airbus

132 000

46.7

DT

61 1640

1.23

93

16e.1

A310-200

138 600

46.7

nT

64 730

1.3

93

168. I

A310-200 Airbus

142 000

46.7

PT

66 310

1.33

93

IhP.1

A310-300 Airbus

150 000

47.0

DT

70 500

I .42

93

1fie.1

A310-300 Airbus

157 000

47.4

DT

74 42n

1.43

93

168.1

Airbus

1.28

-

1.34

-

-

A320-100 Airbus Dual

66 000

47.1

D

31 090 93

A320-100 Airbus Dual

68 000

47.1

D

32 030

A320-100 Airbus Dualtandem

68 000

47.1

A320-200 Airbus Dual

73500

47.0

A320-20Q Airbus Dual Tandem

73500

47 .O

BAC 1-11 S e r i e s 400

39690

47.5

D

18 853

53

0.93

-

-

BAC 1-11 S e r i e s 475

44679

47.5

D

2 1 223

62

0.57

-

-

BAC 1-11 S e r i e s 500

47 400

47.5

D

22515

53

1.08

-

-

BAe 146 S e r i e s 100

37 308

46.0

D

17 162

0.80/0.52 71

-

-

BAe 146 S e r i e s 200

40600

47.1

D

19 123

0.88/0.61 71

-

-

B707-120B

117 027

46.7

DT

54652

1.17

86

B707-320B

148778

46 .O

DT

68438

1.24

142 88

167.1

B707-320C Freighter

152407

46.7

DT

71174

1.24

142 88

167.1

78 DT1.12 030

93

D 1.45

550

78 DT1.21 550

93

32

100

34

-

34

100

142

-

126.8

Option

-

126.8

166.0

Option

152 407

46.7

DT

71 174

1.24

88

143 335

46.0

DT

65 934

1.24

88

104'

47.4

DT

49 451

1 .oo

81

106 594

46.4

DT

49 460

1 .oo

81

73 028

47.8

D

34 907

1.09

86

77 110

47.6

D

36 704

1.14

86

78 471

48.5

D

38 058

1.15

86

84 005

48.0

D

40 322

1 .02

86

86 636

47.7

D

41 325

1.06

86

89 675

46.9

D

42 058

1.15

86

95 254

46.5

D

44 293

1.19

86

44 361

46.2

D

20 495

0.95

78

45 722

45.4

D

21 215

0.97

78

52 616

45.5

D

23 940

1.I4

78

52 616

45.5

D

23 940

0.66

78

53 297

46.4

D

24 730

1.16

78

56 699

46.3

D

26 252

1.23

78

326

B737-200 Advanced

58 332

46.0

D

26 833

1.25

78

-

-

B737-300

61 462

45.9

D

28 211

1.34

78

-

-

B737-300

61 462

45.9

D

28 211

1.14

78

-

B737-400

64 864

46.9

D

30 421

1.44

78

B737-500*

60 181

46.1

D

28 020

1.34

78

-

-

323

23.4

COM

75 678

1.50

112

147

184.8

Main U / C 4 No. DT u n i t s Data hased on e q u a l l a a d distribution

334 749

23.1

COM

77 327

1.56

112

147

184.8

Main U / C - 4 No, DT u n i t s Data based TI e q u a ll o a d distribution

341

23.1

COM

78 899

1.32

112

147

184.8

B747-100B SR

260 362

24.1

COM

62 747

1.04

112

147

184.8

Main U / C - 4 No, DT u n i t s Data hased on equalload distribution Main U / C - 4 No. PT u n i t s n a t ah a s e d on equal load distribution

B747-SF

302 093

22.9

COM

69179

1.30

110

137

175.7

4 No. DT u n i t s Main U / C Data based on e q u a ll o a d distribution

B747-SP

318 881

21.9

COM

69 835

1.40

110

137

175.7

Main U / C 4 No. DT u n i t s Data based on e q u a ll o a d distribution

B747-200B

352 893

23.6

CON

83 283

1.37

112

147

184.8

Main U / C - 4 No. DT u n i t s Data based on e q u a ll o a d distribution

B747-100

410

8747-100B (Passenger) 8747.-lQOB

42

553

"Preliminary information,

'

-

-

B747-200C

23.1

86233

1.30

z 12

184.8

Main U/C

- 4 No.

DT u n i t s

Dntn based on equal. load distribution 23.2

87 975

1.39

111

184.8

Main U/C - 4 No. I)T u n i t s nata hased on equelload distribution

B747-400

23.4

92 661

1.41

112

184.8

P3in IT/C 4 No. DT u n i t s Data based on equal load distribution

B757-200

45.2

49 411

1.17

86

142.8

B767-200

46.1

66 431

1.31

114

lF2.1

B767-200-ER

46.9

74 925

1.21

114

183.1

8767-300

47.5

75841

I .21

1, 14

182.1

B767-3UO-ER

40.9

R 1 052

1.31

114

182.1

8767-300-EK

46.0

R5 339

1.38

114

182.1

Carnvclle 10

h6.1

23 966

F0.75 R1 .I7

R413 F4 5

11.5.1

Cnruvelle 12

46

25 743

Ffl. 69 R1 .flP

na

114.1

R4 1

Concordc

48.0

88 803

1.2h

Canndair CI, 44

47.5

4 5 461.

1.12

cv

a00 M

46.6

4 0 901

1.03

55

126.6

cv

990

48.5

S6 098

1.18

til

1. 3 :?H

46.8

5 349

0.31

-

DC-3

68

180.3

F51

137.5

R7ri

.

-

-

1

-

15 480

0.53

74

-

67 073

1.22

76

140

159.3

DT

69 926

1.28

76

140

159.3

DT

71 413

1.30

76

140

159.3

46.5

76 858

1.29

81

140

161.7

DT 386 162

47.6

77 296

1.30

81

140

161.7

DC-9-15

41 504

46.2

D

19 175

0.90

61

-

-

DC-9-21

45 813

47.2

D

21 624

0.98

64

-

DC-9-32

49 442

46.2

D

22 842

1.07

64

DC-9-41

52 163

46.7

D

24 334

1.10

66

-

DC-9-51

55 338

47.O

D

26 009

1.17

66

MD-81

63 957

47.8

D

30 539

1.17

71

-

-

68 266

47.6

D

32 460

1.27

71

-

-

MD-83

73 023

47.4

n

34 613

1.34

71

-

MD-87

68 266

47.4

D

32 358

1.17

71

-

-

DC-10-10

DT 942 200

46.9

94 141

1.31

137

163

212.9

DC-10-10

196 DT 406

47.2

92 605

1.28

137

163

212.9

DC-10-15

DT 746 207

46.7

96 914

1.34

137

163

212.9

Loading based onwing DT. Main U / C includes central D.

DC-10-30140

COM 981 268

37.9

101 944

1.24

137

163

212.9

Loading based on wing DT. Main U/C includescentral D.

COM 105 253

37.7

1.17

137

163

212.9

Loading based onwing DT. Main [T/C includescentral D.

33 113

46.8

DC-8-43

DT 242 144

46.5

DC-8-55

148 778

47.O

DC-8-61/71

148 778

48.O

DC-8-62/72

DT 121 160

DC-8-63173

DC-4

MD-82

188

D

95 421

I

-

-

-

260 816

37.6

COM

98 069

1.21

137

Loading based on wing DT. Main U/C i n c l u d e s c e n t r a l D.

274 650

39.2

COM

107 663

1.41.

I37

Loadingbased on wing DT. Main [[/I: i n c l u d e s c e n t r a l

19 867

46.8

D

9 228

0.74

42

19 777

47.5

D

9 394

0.54

45

20 820

47.8

D

9 952

0.59/ 0.55

52

20 820

47.8

D

9 952

0.42

52

29 484

46.3

D

13 651

0.58

58

29 484

46.3

D

13 651

0.69

55

44 680

47.8

D

21 357

0.98

59

10 600

45.5

D

4 824

0.77

32

1 3 340

45.5

D

5 160

0.83

32

21 092

43.6

D

9 196

0.59

48

162 600

47.0

DT

76 910

1.08

80

168 000

47.0

DT

79 460

1.08

80

171 000

23.5

COM

38 730

0.59

-

-I -I

211 500

31.2

COM

64 390

0.88

125

s1 I-

I@ 88 I#I# IS

Main V/C 3 DT u n i t s

S S1

62

144

n.

.. -

.

. -

,

MAIN LEGS OF LANDING GFAR Load on All-up oqc main maRRpressure leggear ea& 1%

(X)

(kg) type Aircraft

.

Load on

'fire Wheel spacing ( c m )

Wheel arrangemeqp

(kg1

(ma)

(s)

(ST)

(SD)

154

-

-

. . .

..

L-100-20

70 670

48.2

T

17 031

0.72

-

L-100-30

70 670

48,4

T

17 102

0.72

-

154

Additional data f o r complex wheel arrangement Main wheeJs arranged i n tandemon fourseparate legs. Maln wheels arranged i n tandem on fourseparate legs.

L1011-1

195952

k7,A

DT

92 881

1,33

132

178

221.6

L-loll-lao/2oo

212 281

46,8

DT

99 348

1.21

132

178

221.6

L-1011-500

225 889

46.2

DT

178

221.6

Trident 1E

61 160

46.0

CON

28 196

1.03

-

-

-

Trident 2E

65 998

47.0

COM

31019

1.07

-

-

-

Trident 3

68266

45.5

COP

31 095

1.14

c

-

-

TU134A

49 000

45,6

DT

22 690

0.83

56

99

113.7

TU154B

98 000

45.1

COM

44 198

0.93

62

F103 R 98

223.6

'7

48.3

DT

73 317

1.01

86

155

177.3

IN

VC10-1150

151953

104361

132

1.27

I I

I C A O 7357 P A R T * 3

t f

= 484143b

00396313 837

=

APPENDIX 2

.

1.

PROCEDURES FOR D E T E R M I N I N G THE AIRCRAFT C L A S S I F I C A T I O N NUMBER OF AN AIRCRAFT

Rigid pavements

1.1 The ACN of aani r c r a fftoorp e r a t i o nosn d e t e r m i n e du s i n g ComputerProgramme No. 1.

a r i g i d pavement s h a lbl e

m.

- Computer LPtmpamnz Eo. 1 i s basedon programre PDILB developed by Mr. R.G. Packard of Portland Cement Association, IZZino-is, United States, for dgsign of r i g i d pavements. For convenimce, severai! a i r c r a f t t y p e s currentZy i n use have been evaluated on ~ g i pavements d fovndgd 071 the four strbgradg categories at Annex 14, Chapter 2, 2.5.6 b ) and the results tabulated in Attachment E, Table 15-1 of t h a t Annex and Table Ab-1 of Appendix 5 of t h i s l d a n m l . 2.

F l e x i b lpea v e m e n t s

2.1 The ACN o f a ani r c r a fftoor p e r a t i o n s d e t e r m i n e d u s i n g ComputerProgramme No. 2.

on a f l e x i b l e pavement s h a lbl e

€?ate.- Computer Programme No. 2 i s based OH. the United States Amny Engineer's CBR method of design of f l e x i b l e pavements (see United States A - m y Engineer Watermays Experiment Stcfiion I n s t r u c t i o n Report 5-77-21. For convenience,=vera2 aircraft types currentZy i n use h u e been evatuated on fZe3cibI.e pavements founckd on the four subgz.ade categories a t Annex 14, Chapter 2, 2.5.5 b ) and the results tabulated i n Attachment B, TabZeB-1 of t h a t AnnexandTabZeA5-1 of Appendix 5 of t h i s I d a n u a Z .

3-251

I C A O 9157 PART*3

**

= YBY5Lthb 0 0 3 9 6 3 57 7 3

m

Aerodrome Design Manual

3-252 Computer Programme No. 1 The purpose of these instructions operating the computer programme.

i s toprovidetheinformationneededfor

Abstract D e s c r i p t i o n .T h i s programme d e t e r m i n e sf l e x u r a l stresses in a c o n c r e t e pavement f o r a i r c r a f t g e a r l o a d s , t h e r e q u i r e d c o n c r e t e t h i c k n e s s f a r t h e i n p u t s u b g r a d e and 2.75 MPa c o n c r e t e stress and ACNs of a i r c r a f t . It i s based on W e s t e r g a a r d ' sa n a l y s i s forloads a t theinteriorof a pavement s l a b supportedby a denseliquidsub-base. Loads are assumed t o b e u n i f o r m l y d i s t r i b u t e d on e l l i p t i c a l s h a p e s r e p r e s e n t i n g tire c o n t a c t areas. The p r o g r a m e i s o p e r a t e d i n o n e o f t h e f o l l o w i n g

modes*:

-

Mode 2.

Pavement e v a l u a t i o n F o r a n e x i s t i n g pavement,thicknessand s u b g r a d e s t r e n g t h known, t h e programme g i v e s t h e maximum stress f o r t h es p e c i f i e dl o a d i n gc o n d i t i o n . This node is used by t h e designer to determine if an existing pavement is s t r u c t u r a l l y a particular aircraft. adequateforoperationof

Mode 5.

I f Mode 5 is i n p u t , t h e programme iterates t o f i n d t h e r e q u i r e d 2.75 MPa c o n c r e t e concretethicknessfortheinputsubgradeand

stress. Mode 6 .

I f Mode 6 i s i n p u t , t h e programme iterates t o find t h e r e q u i r e d t h i c k n e s s f o r t h e s t a n d a r d ACN/PCN s u b g r a d e c a t e g o r i e s a n d t h e s t a n d a r d c o n c r e t e stress of 2.75 "Pa, p l u s t h e ACN v a l u e s f o r the standard subgrade categories. Specifications

B IM 1130 Monitor FORTRAN. IBM 1130 (1131 CPU, 8R, w i t h DISK), 1442 Card Read Punch,1132 P r i n t e r( o p t i o n a l ) Programme type:Mainlineprograms (PDILE) andfour sub-routines (INMAX, PARAB, CN7G and CACN).

Language : Equipment :

Input Input cards for each of the three and sample inputs are shown onpage 3-257.

modes are punched as shown i n F i g u r e A2-1

Co-ordinates of wheels.In a l l of t h ei n p u tf o r m a t s , X-Y co-ordinatesof w h e e l c e n t r e s are u s e d t o s p e c i f y w h e e l s p a c i n g s , w i t h t h e X - d i r e c t i o n i n d i c a t i n g t h e l o n g i t u d i n a la x i so ft h ea i r c r a f t . * *T h i s means thatspacingbetweendualwheels is s p e c i f i e d a s a Y-dimension and spacing between tandem wheels is s p e c i f i e d as a n X-dimens ion.

* **

SeeReference 4 f o r u s e o f ?lodes 1, 3 and 4 . This convention must be followed in a l l modes of operation since the computer axis of e a c h c o n t a c t area e l l i p s e i n t h e programme i n i t i a l l y o r i e n t s t h e m a j o r X-direction.

25/10/85 No. 1

I C A O 9357 P A R T * 3 t t P a r t 3.-

=

4843436 0039632 bOT 3-253

Pavements

The f o l l o w i n g c o n s i d e r a t i o n is a l s o i m p o r t a n t i n s p e c i f y i n g t h e w h e e l co-ordinates. The p a r t i c u l a r wheel i n t h e g e a r t h a t i s j u d g e dc l o s e s tt ot h el o c a t i o n of maximum stress is d e s i g n a t e d as Wheel 1 and i t s c o - o r d i n a t e s are set a t X = 0.00, Y = 0.00. The o t h e rw h e e l s are numbered as d e s i r e d and t h e i r X-Y c o - o r d i n a t e s are s p e c i f i e dc o r r e s p o n d i n gt ot h e i rp o s i t i o n relative t o Wheel 1. S k e t c h e s 1 and 2 of F i g u r e A2-2 i l l u s t r a t e t h e p o s i t i o n s a n d w h e e l c o - o r d i n a t e s f o r d u a l w h e e l g e a r a n d f o r dual-tandemgear.Sketches 3, 4 and 5 of t h e same f i g u r e show t h e s e l e c t i o n of Wheel 1 f o r morecomplex g e a r c o n f i g u r a t i o n s . Of t h e two mostcloselyspacedwheels i n a-complexconfiguration,thewheelclosesttothegearcentre is usuallyselected as Wheel l.* output Sample r e s u l t s f o r e a c h o f t h e modes are g i v e n on pages 3-258 t o 3-260. The f i r s t p a r t of t h e o u t p u t , down t o a n d i n c l u d i n g MODE, r e p r e s e n t s a r e p r o d u c t i o n o f t h ei n p u td a t a . The r e m a i n i n gd a t a are t h e r e s u l t s of computationsand are d i s c u s s e d s e p a r a t e l y a c c o r d i n g t o mode i n t h e f o l l o w i n g p a r a g r a p h s . COUNT are p r i n t e df o re a c hw h e e la n d Mode 2. I n t h i s mode, F-valuesand are t o t a l l e d . T h e s e v a l u e s are r e l a t e d t o stress andbending moment as f o l l o w s :

Ft = CoUNTtt

STRESS =

(Bending moment) (Contactpressure) =

1 0 000 x ( F ) (Rad. rel. s t i f f . ) Z

6 x (Bending moment) (Thickness)Z

--

6 x (F) x ( C o n t a c t p r e s s u r e ) (Thickness)Z

CODES 0 , 1 and 2 i n d i cr ea st ep,e c t i vwehl yei,tnhdeirv iw d uhaele l s inside,partiallyoutside,orcompletelyoutsidethe programme'szone ( r a d i u s of 311).

are of influence

A t t h e endoftheprint-out, maximum stress a n d t h e l o c a t i o n a n d d i r e c t i o n (XMAX, YMAX a n d ANGLE) of maximum stress are l i s t e d .

M A X .

numberof

Mode 5. iterations.

T h i so u t p u t

i s similar t o t h a t o f

Mode 2 w i t h t h e a d d i t i o n o f

Mode 6. T h i so u t p u t i s similar t o t h a t of Mode 5 e x c e p tt h a tc a l c u l a t e d v a l u e s are r e p e a t e d for each subgrade, and the ACN v a l u e s are added.

*

Conceivably,foranunusualgearconfigurationwith a number o f closely spaced as Wheel 1 might wheels,separatecomputerrunswithdifferentwheelsspecified b er e q u i r e d . I-The f a c t o r , F, is used t o c o n v e n i e n t l y e x p r e s s a m e a s u r e o f t h e r e l a t i v e b e n d i n g moment i n d e p e n d e n t o f c o n t a c t p r e s s u r e . I-? COUNT i s l i s t e d s o t h a t t h e u s e r c a n v e r i f y computer r e s u l t s . T h i s i s done by comparing COUNT a g a i n s t t h e number o f i n f l u e n c e b l o c k s c o u n t e d on P i c k e t t a n d Ray'sInfluenceChart No. 2 .

25/10/85 No. 1

I C A O 9157 PARTs3

**

U 4Brllr4Lb 0059633 5rlb

3-254

A e r o d r m Design M a n u a l

Programme L i s t i n g A l l F o r t r a n programme s t a t e m e n t s a r e l i s t e d s t a r t i n g

on page 3-261.

Limitat i o n s A l l c o n t a c t areas are a s s i g n e d equal size, shape and c o n t a c t p r e s s u r e . Analysis of a set o f c o n t a c t i m p r i n t s w i t h d i f f e r e n t s h a p e s , a r e a s o r p r e s s u r e s w i t h i n t h e s e t would r e q u i r e a m o d i f i c a t i o n of t h e programme.

The programme computes stresses f o r t h e c o n t a c t a r e a s , or portionsthereof, t h a t are w i t h i n a r a d i u s of 3a cm from t h e s e l e c t e d r e f e r e n c e Wheel 1. Forcontact areas o u t s i d e t h i s bound, t h e stress i s set t o z e r o . References: 1. P i c k e t t , Gerald and Ray, Gordon K., I?a37!ue~eC = h c ~ ~f oki a Concz.e te _Pdt'ernent~, American S o c i e t y of C i v i l E n g i n e e r s Tramaoti-om, Paper No. 2425, Vol. 115, 1951,pp. 49-73.

2.

Dzsigz of Concrete Aiz+Ejoz>t Pavement, P o r t l a n d Cement A s s o c i a t i o n ,C h i c a g o ,I l l i n o i s .

3.

P i c k e t t ,G e r a l d ;R a v i l l e ,M i l t o n

E.;

Janes, William C.;

and McCormick, Frank J., €avrrncntsJ Kansas State

LkflecCiona, M~meratsand Reactive B e s c m e c foil Ccmcrete C o l l e g eB u l l e t i n No. 65, Oct. 1951. 4.

Packard, Robert: G., Computer Program for? Airport Puverw?2t E ~ s i p ,P o r t l a n d Cement Association, Chicago, I l l i n o i s .

25/10/85

No. 1

.

**

I C A O 9157 PART*3

Y 8 4 1 4 1 b 0019634 4 8 2

P a r t 3. - Pavements

f

3-255

CARD 1 6 9 10 11 12

13

14

15

16

17

18

19

20

21

22

I

24 725 1 7226 7327 742877 7529 787630 79 31 80 70

23

IIIII-IIIIIIIIIIII CARD 2

IS I

I

I

1 2

54 6 7

3

8

10 9 11 12 13 14 15 16 I7 18 19 20 21 22 23 24 25 26 27 28 29 30 77 7831 7970 80 71 72 73

I

8 AIRCRAFT

GEAR

!Sr $

TIRE PRESSURE

AIRCRAFT MASS

(kPa)

1 2 3 4 5 6 7 8 9 10 11112 13114 15116117118119 20 21 22 23 24 25126 27 1 1 2 9+I

B-797

M A I W 09

II

13152 8 4 3

I

1

PERCENT MASS ON MAINLEGS GEAR

113 ? l a l *

9

54.y.

1 2 3 4 5 6

SLAB THICKNESS I

I

1. 2. 3. 4. 5.

IY*

I

LAST CARD I

1 2 3 4 5 6 7 8 9 10111213141516171819202122232425262728293031

Notes:

II

8 10911 12 13 14 15 17 18 16 19 21 20 22 23 24 25 26 27 28 29 30 31 70 71 72173 77 78 74175 79 76

7

SUBGRADE k

I

I CARD FOR EACH WHEEL (UP TO 20 WHEELS)

Y

I

CARD 3

321331u 35 36 3713 3 9 b 4 1 4 2 b 44 45 4447 48 491451 5’453 54 55

COORDINATES OF W H E E L S O

X

NUMBER OF MAIN GEAR LEGS

0 71 72 73 74 75 77 76 78 79 80

I

Number of problems. Optional output; use 1 for typewriter, 3 for line printer. Desiredmode of operation. Totalnumber of wheels in gear@) being analyzed. (Use column 14 if less than 10 wheels.) X- and Y-coordinates of wheel centers. X-direction indicates longitudinal axis of aircraft; e.g. dual wheel spacing is Y-dimension, tandemspacing is X-dimension.

F i g u r e A2-1.

Input Form f o r Modes 2 , 5 and 6

25/10/85

ao. 1

Aerodrome Design Manual

3-256

o.0o:o.oo

0.0 0 ;0.00

x

Sketch 3

172.72 I O . 0 0

IY

Sketch 5

0 0

0 0 0 Figure A2-2.

25/10/85 No. 1

'

4

0

Wheel Co-ordinates and Selection of Wheel 1

X

Sketch 4

-

Part

3-257

Pavements

SAMPLE INPUTS

Mode 2

3

: 3

2 8-747 MAIN04 0.00 0,oo 0.00 111.76 147.32 0.00 147-32 111-76 80.00 30.48

352893.

1370.

94.4

1370.

94

Mode 5

5 8-747 MAIN04 352893. 0.00 0.00 0,OO 1 1 1-76 147.32 0.00 t47.32 111.76 30.48 80,OO

-4

4.

Mode 6

6 €3-747

0.50 0.00 147.32 147.32 80.90

MAIN04 352893, 1370-

0.00

.

94.4 .

.

.__

4.

..~ .-

1 1 1.76 0.00111.76 30.48

25/10/85 No. 1

I

I C A O 9557 PARTS3

**

YClYLLiLb 0 0 5 9 b 3 7 595

3-258

Aerodrome Design M a n u a l

SAMPLE OUTPUTS AI R C XFT 0-747

GZAR-

NO.

MAIN

O F W HCLOSN. T A C RCO ET AN T PA RC ET S S U R E 14 . 3 7 1491-64

C O O R D I N A T E S O F WHLS. NO. X Y

0.00 0.00 -

1

r

0.00

3

1 1 1.76-

0.00

147.32 1 14 17 1. 3. 72 6

4 MODE

K S U B BSAUSBEG RPAADVEE MT EHNI CT K i J E S S

2

80.00

NO.WHL, WHL. WHL. UHL.

NO. NO.

NO.

3 0 .4

1 2

STRESS

AIRCR G AE FA TR

NO. MAIN

0-?47

C O O R D I N A T E SO F N0, X

1 2 3

0.00 0.00 147.32 147-32

'~

4 W O DE

44.4532 1.3062 3,0917 3.4945 52.3457

YMAX -0.5

X M A X -0.4 MAX

F

F 3 F 4 F TOTAL F

CODE CODE CODE CODE PIAX.

0 0 0 0

COUNT COUNT COUNT COUNT T O T A LC O U N T

ANGLE

318.4 9.4 22-1 25.0 375-0

57.6

3.0

O F WHLS. 14 . 3 7

C O NC ATO RA E N CPATRA ECST S U R E 1491.64

lJHLS, Y

0.00 11 1-76

0.00 111.76

K S U B B SA U S EB G R AP D AV E E M TE H N ITC K N E S S

5

80.00

32.6 99-91

R ARDE.SLT. I F F , WHL. NO. WHL. NO. WHL. NO. WHC. NO.

X M A X -0.5 S T R E SMSA X .

25/10/85

No. 1

1 2 3 4

F

F

F F TOTAL F

55,1260

Y M A X -0.5

2.8

CODE 0 CODE 0 CODE 0 CODE 0 TCOOTUANLT

45.5237 1.8989 3.6762 4.0273 MAX.

ANGLE

ITERATIONS

COUNT COUNT COUNT COUNT

294.2 12-3 23-8

26.0 356-3

57.7 8

I

I C A O 7357 P A R T * 3

**

= 484143b

1

0017638 028

Part 3 . - Pavements

3-259

A I R C RGAEFATR

NO,

8-747 COORDINATEO SF NO. X

1 2 1 4 7 3. 3, 2 4 41-6

MODE 6

4

-64

ACROENATPARCETS S U R E

1.37

1491

WHLS. Y

0,oo

0.00 0.00

111.76

147.32

1 1 1 -76

0.00 K

S U B B A S E S U B G RPAADV EE M E N T -

THICKNESS

20.00 170.49

RAD R,E S L .T I F F . WHL, WHL. WHL. WHL.

NO. NO. NO.

NO.

1 2

F F 3 F 4 F TOTAL F

XMAX -1.2

MAX.

MODE

O F WCHOLNST. A C T

MA I N

K

56,6440 9,8882 11.6214 11,4935 89,6472

YMAX - 0 . 9

2.8

STRESS

CODE 0 c- I!LJ!.I13-53-72 1 -9 CODE 0 C 0 UNT 25.8 CODE 0 C 0 UNT CODE 0 COUNT 25,s C TOU TA N LT 199.0 MAX.

ANGLE

5 8. ..~2 .

ITERATIONS

7

ACN

COUNT COUNT

189-8 21.1 27.6 27-9 266-4

73,6

S U B BS AUSBEG RPAADV EE MT E HN I CTK N E S S

6

37.3

40.00

132-07

R A DR.E LS .T I F F . WHL. WHL. WHL. WHL.

NO. NO. NO.

NO,

XMAX - 0 . 9 S T R EM S SA X .

1 2

F F

3

F

4 TOTAL

F

F

YMAX

2.8

51.3276 5.7093 7,4554 7.5330 72.0253

-0.7

CODE CODE CODE CODE

0 0 0 0

COUNT^ COUNT

TCO OTUANLT AMNAGXL. E ITERATIONS

I

58.0

4

ACN- 64-1

25/10/85 No. 1

ICAO 3LS7 P A R T * 3

**

48414Lb 00Lqb33 Tb4 W Aerodrome Design M a n u a l

3-260’ HO D E

K S U B B AS SU EB G R AP DA EV E M ET N H TI C K N E S S

6

80.00

32.7 100.80

R A DR.E LS.T I F F . WHL. WHl. WHL. WHC.

NO. NO. NO. NO,

~~

MODE

1 2 3 4

-0.5

MAX.

STRESS

45,7074 2.0044 3.7804 4.1225 55.6147

Y M A X -0.6

2.8

CODE 0 C 0 UNT CODE 0 COUNT CODE 0 COUNT CODE 0 co UNT C OTUONT TA L MAX.

ANGLE

ITERATIONS

290.2 12.7 24.0 26.2 353m2

57.7 4

ACN

COUNT C 0 UNT COUNT COUNT

426.6 -6.0 13.3 19.4 453.3

53.9

K SUBBASE S U B G RPkADVEE MTEHNI C TKNESS

150,OO

WHL.

WHt. WHt. WHL,

NO. NO. NO, NO.

28.8

1 2 3 4

XMAX -0.0

MAX

.

F F

F

F TOTAL F

._-

No. 1

F

F TOTAL F

XMAX

6

25/ IO/85

F F

STRESS

YMAX

2.7

40.4128 -0.5664 1.2575 1.8376 42,9415

-0.3

CODE 0 CODE 0 CODE 0 CODE 0 C T O TU ANLT MAX.

ANGLE

ITERATIONS

57.3 4

ACN

45.3

ICAO 7357 P A R T * 3 *Kt

4841436 0039640 786

PROGRAMME L I S T I N G COMPUTER PROGRAMME NO.

1

R I G I D PAVEMENT ACN

10 20 30 40 50

60 70

80 90 100 110 120

c C C

APCRNORGI A RAM PROGRAM ACNRI

IINSUT N . ITS A D J U S TI M NSC EUU NGD TG S EEDS T E D

B YGOVERNNENT AUSTRAL1 EN C C C JUNE 1979 MODIFICATION TO P C A / P D I L B TO COMPUTE ACN VALUES F O R STANDARD C SUBGRADES PER I C A O ACN/PCN METHOD, C

c c c

130 COMMON I O U T D I M1 E4 N 0 SS U IBO SKU NI (B7K) Ir I ( 7 ) X(2O)rY(2O)rAIRCR(2>rE(lO)rST(14)rDX(14),F~2~~3~ D I M E N1S5I0O N 160 DIMENSION BETA(20)rA(14),B(14)rXU(ZO) 170 C SAVE SPACE ACN/PCN FOR STANDARD SU3GRADES 18 0 D I M E N SAICONNKD(F4W ) r H L (D2 C O 3I) D rU2CV 0O )T D c ECZO) 190 C 200 c D O U BPLR EE C I S I O CN A RN DE SE DD ED EPENDING ON ACCURACY O F M A C H I N E 210 c M( TAHCIHSI N E 16 DED CIG YR I TLS F O R DOUBLE PREC.) c 220 230 DOUBLP ERECISION A~AC~ACNIACNKIALPHIALPHDIAMAXIAMAX,AMIN,AQDRT,AREA,AS, 240 + AXIB,BETAIBQDRTIBXICICOUNTICQDRT~DIDCOUNT,DENOM,DFWHL,DIFFO, 250 + DIFFlrDISCR~DTHET~DV~~~DV~OO,DVl~~DV2~DV2O~DV6~DV6O~DX~DlO 260 + D12rD120,D2,D20rD4rD40,06~D6o~D~~D~~~E~F~FACC~FCTN~FELM~FT~T~ 270 ~ P I E I P X ~ , P X ~ I P ~ ~ P ~ ~ Q I R A I R ~ ~ R S L T I S I S L T ~ S ~ ~ ~ ~ ~ S L P ~ ~ S L ~ 280 + STOR~~STOR~~STRSISUBKITHET/THET~~THET~,THET~,TOTCT,V~~V~~X~XHN~ 290 + XMAXIXNPXNMR~XUIXXLIY,YMAXIYN,Y~~Y~~Y~~Y~~XINTRM 300 DATA S U B K I / 2 O . r 2 S , r 4 0 . r 6 O . r 8 3 . r 1 2 3 . r 1 5 3 . / 3 10 X INCH2=6.4516 320 X I N C H = 2.54 330 XPRES = 1 4 5 , 0 3 7 7 4 3 8 340 XPOUND = 2 . 2 0 4 6 2 2 5 350 PIE=3,1415926535898 36 0 J BS=O 370 READ(5r100)JOBS#IOUT 380 100 F O R M A T ( I ~ , ~ X I I ~ ) 39 0 WRITE(IOUT,lOl) 40 0 1F0O7R M A T ( ' ' / / / / ' '~~~XI'AIRPOR PA TVEYEN DT E D S I G N ' /U/ /N' I T S KG 410 1 CM DEGREES'//) IN 1 40=2270 E A D ( 5 / 1 0 3 ) M O4D3 E 0 103 F O R M A T ( I 1 ) 440 C S AI N VP EMUOTD E T O I N D I C ALTTEE R 9 T IA OANNC CDANL C U L A T I O N S . 450 460 M O D I = MODE 470 I F C M O D I .GT. 4 ) MODE=2 480 G O TO ( 1 0 4 r 1 0 4 r 1 0 7 r 1 0 7 ) r M O D E 140940 READ(5,105)AIRCR~GEAR~MeAf4A!jStPRSW~PflMGpAMLG 150050 FORMAT(ZA4rA4/12~4Eld.O) 510 WT=AMASS*9.815/1000.

.

e

+

e

25/10/85 No. 1

I C A O 9357 P A R T * 3

**

484L4Lb 00lI9b45 b l i !

3-262 520 530 540 550 56 0 570 580

590 600 61 0 620 63 0 64 0 650 660

670 680 69 0 700 71 0 72 0 730 74 0 750 76 0

770 780 790 800 81 0 82 0 83 0 84 0 8 50 860 87 0 880 890 90 0 91 0 92 0 930

94 0 950 960 970 98 0

990 1000 1010 to20 1030 1040 1os0

1060 1070

Aerodrome Design Manual TLMG=WT*PMMG/100. TLSMG=TLMb/AMLG WM=M TLSW=TLSMG/WM AREA=TLSW*IOOOO.O/PRSW Q=PRSW/1000.0 WRITE(IOUTI~~~)AIRCRIGEAR~MIAREAIQ AREA = AREA / X I N C H Z Q = Q * XPRES 1 0 6 F O R M A TI R( 'C R G AE F TA R d HOLNFSO. . C O N TACAROCENTAT A 1 CPT R E S S U R E ' / ' ' I ~ A ~ I A ~ I I ~ ~ I F ~ ~ . ~ I F ~ S ~ ~ / ) G O TO 110 107 R E A D ( S I ~ O ~ ) A I R C R I G E A R I M # A R E A 108 F O R M A T ( 2 A 4 r A 4 r I 2 r F 7 . 2 ) WRITE(IOUTIIO~)AIRCRIGEAR~M~AREA

AREA = AREA / X I N C H 2 109 F O R M A TI R( 'C R G A FE TA R V O . A HOEF E L S CONTACT AREA'/' 141A8rI101F19.2/) 110 R E A D ( S I I I I ) ( X ( N ) I Y ( N ) I N = I ~ M ) 11 1 F O R M A T ( 2 F 7 . 2 ) WRITE (IOUTrl12) 1 1 2 F O R M A TC( 'O O R D I N A T EOSWF H L S . ' / ' VO. X Y' 1 WRITE(IOUTII~~)(NIX(N)IY(N)~~=~I~) 1 1 3 F O R M A T' 1( '1 3 1 F 1 0 . 2 1 F 8 . 2 ) D O 1113 N =I I M X ( N ) = X ( N ) X/ I N C H 1113 Y ( N ) = Y ( N ) / X I N C H G O TO ~ 1 1 4 1 1 1 7 r 1 ~ 0 ~ 1 2 0 ~ 1 M O D E 114 READ(5,IlS)SUBKO 1 1F5 O R M A T ( F 7 . 2 ) WRITE(IOUTI~~~)MODEISUBKO C A L RL S U B K ( S U B K , S U B K O ) 116 F O R M A T ( ' MODE K S U B B AS U E B G R A D E' r' /I '3 1 F 1 7 . 2 / ) G O TO 1 2 7 117 R E A D ( S I I I ~ ) S U B K O I D C A LRL S U B K ( S U B K I S U B K O ) C SSETTA N D ASRUDB G R A D E S U L T R A L 3 d 1 LOWI M E D I UAM SNT#DR O N G . I F ( M O D 1 . E Q . 6) A C N K ( 1 ) = 73.679 I F ( M O D 1 .EQ. 6 ) A C N K ( 2 ) a 147.36 I F ( M O D 1 .EQ. 6 ) A C N K ( 3 ) = 294.72 I F ( M O D 1 .EQ. 6) A C N K ( 4 ) = 5 5 2 . 5 8 C SCUEOPTU N TAELNRODFOSOPTR4 N D AARCDN / PSCUNB G R A D E S . ISUB = 0 1117 I S U B = I S U B + 1 I F ( 1 S U B .GT, 4 ) G O T O 350 I F ( M O D 1 .EQ. 6 ) S UABCK N K ( I S U i 3 ) IS U B I = ( I S U B - 1 ) * 2 +1 I F (MODI 1 E Q a 6)SUBKO=SUBKI(ISUBI) ITCT=O 118 F O R M A T ( F ~ . Z I F S . I ) C STTHA IRCTK C NO ES N SV E R G E N C E LO3P. 1118 C O N T I N U E C D EOL A U YT P U N TCS TOI N L V E R GCEON I SMCPEL E T E . 4 ) G O TO 1 2 8 I F ( M O D 1 .GT. WRITE(IOU~I~~~)M~DE~SUE~KOID D = D/XINCH

'/'

-

9 , 2 ~

ICAO 9357 PART*3 P a r t 3. - PaveEnts

**

48434Lb 0039642 55'7

= 3-263

1080 119 FORMAT(' ' / ' MODE K SUBBASE SUSGRADE P A V E M E N T THICKNESS'/* 1090 1 'rI3rF17.2eF21.1/) 1100 G O TO 1 2 8 1112100 WRITE(IOUTe121)MODE 1 1 20 121 F O R M A T ( ' ' / ' MODE'/' '#13/) I F ( M O D E - 3 ) 112123r01 2 2 ~ 1 2 4 1 2 2 SPCFL=O.O 1140 1150 123 AMAX=O.O 1160 G O T O 129 . 1110 124 READ(~~I~~)SPCFLIAMIN~AMAX 1180 SPCFL = SPCFL/XINCH FORMAT(F6,2e2(F6.1)) 125 1190 1200 ALPHD-AMIN ALPH=AMIN/180,*PIE 1210 1220 WRITE(IOUTII~~)AMIN,AMAX * 1230 126 F O R M A T ( ' R O T A T E FROM',F6.1r1 TO'rF5,l.' DEGREES'/) 1240 G O TO 1 3 0 1250 127 D=lO.O XXL=DSQRT(D**3/SUBK) 128 1260 I FCXXL.LT.0.) XXL=O, 1270 1280 SPCFL=24.1652*DSQRT(XXL) 1290 G O TO 1 2 3 1300 129 ALPHZO. 0 1310 ALPHD=O,O I F (MODE-3) 134,134,130 1320 WRITE(IOUT,131)ALPHD 130 1330 1340 131 F O R M A T ( ' R O T A T I O N ANGLE'rF7.1/) 1350 1 3 4 D O 3L2=02 0 r 1 0 0 1 1 0 XL=L 1360 IFCSPCFL ,NE. 0 1 XL = SPCFL 1370 I F C M O D I ,GT. 4 ) G O T O 138 1380 1351390 IF(MODE-2)138rl36,136 1 3 61 4 0 0 XLO = XL*XINCH 1410 WRITE(IOUTe137)XLO FORMAT(' RAD, REL. S T I F F . ' , Fi'.i?r/> 1371420 1381430 AX=O.S*(DSQRT(AREA/.5227)I/XL BX=AREA/(PIE*AX*XL*XL) 1440 1450 FWHL=O.O F T O T = 0.0 1460 1470 FACC'O.0 K=l 1480 1391490 D O 196 N=I,M YN=Y(N) 1500 1510 XN=X(N) 1520 G O T O (140,143e140r14a)rMODE 1401530 IF(K-2)141r147r148 1411540 XF(Y(N)*X(N))145,142el45 1421550 IF(Y(N))144,143r144 1560 1 4 3 BETA(N)=O. 1570 G O TO 1 4 6 1441580 BETA(N)=PIE/Z. G O T O 146 1590 SETA(N)=DATAN(Y(N)/XO) ? 600 145 161 0 1 4 6 ALPH=-BETA ( N ) 1620 GO T3 148 1471630 ALPH=PIE/Z.-BETA(N) ~

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Aerodrome Design Manual

1640 148 XHN=DABS(XN/XL) 1650 XKN=DABS(YN/XL) C=(AX*XKN)**2+(BX*XHN)**Z-(AX*BX)**2 1660 C ) 1 6 0 r 1 6106r 1 74 09 IF(AX-DABS(XHN))150rl59r150 1680 149 1690 150 SLPlt(-(XHN*XKN)-DSQRT(C))/(AX**2--XHN**2) 1700 SLPZ=(-(XHN*XKN)+DSQRT(C))/(AX**2-XHN**2) 1710 IF(SLP2-SLP1)151r152rl52 1720 151 STORJ'SLPZ Pz=sLPl 1730 l=STOR3 1740 1 5 2 THET2=DATAN(SLP2) 1750 I F ( X H N ) I S ~ ~ I S S R I S ~ 1760 1770 153 IF(SLP2-XKN/XHN)lSSrIS4~15~ 1I17 F58 (4 S 0t P 1 ) 1 5 7 ~ 1 5 6 r 1 5 6 1790 155 THETI =PIE-DATAN(DABS (SLPI) 1 1800 G O TO 158 THETloDATAN(SLP1) 1810 156 1820 G O TO 158 T H E T I = - D A T A N ( D A B S (SLP1)) 1830 157 DTHET=(THET2-THETI)/20.0 1840 158 1850 THET=THEfl+DTHET/Z.O 1860 G O TO 1 6 1 SLPl=(XKN**2-BX**2)/(2.o*XHN*XKt~) 1870 159 1880 THET2=PIE/2.0 G O T O 154 1890 THET1=(-2.0*PfE)/88.0 1900 160 DTHET=(2.O*PIE)/ 1910 88.0 1920 J =44 1930 s=-1.0 THET=THETI+DTHET 1940 1950 G O TO 1 6 2 J=20 1960 161 1970 S=I.O 1980 162 D O 186 I = l r J 1990 IF(THET~(PIE/2.0))163~165r163 2000 163 IF(THET-(3.O*PIE/2.O))164r165r164 201 0 164 S L P = D S I N ( T H E T ) / D C O S ( T H E T ) DRT+BX**2+(AX*SLP)**2 2020 2030 BQDRT=-(2.O*XHN*BX**2+2.0*XKN*SL3*9Y**2) 2040 C Q D R T " ( B X * X H N ) **2+(AX*XKN) * * 2 - ( A X * 3 X ) * * 2 2050 DISCR=BQDRT**2-C.O*AQDRT*CQDRT 2060 IF(DISCR.LT.0.) DISCR=O. 2070 PXI=-S*A(8)) * -022224 261 0 D100= (B(IO)-S*A(Io)) * ( -.00428 ) 2620 ( 8 (D1l22)0- = S*A(12)) * ( -.000105 1 ( V 2 *D 8< V22)0-=S2 *6V3l0* A ( 2 ) ) * 2.25 2640 (DVV2 6* 80 (=6 ) - S * V I * A ( 6 ) ) * ( -.31639 1 2650 D V 1Oo= (V2*B(lO)-S*Vl*A(IO) 1 * .003944 2660 DIFFO=D120+DV100+D10O+D80+DV6OtD~O+D4O+D2~+DV2~+O,~-~.~*S 2670 DIFF1=DV14+D12+DV10+DlO+D8+DV6+D5+D$+D2+DV2 Y 6 =2D6S8I0N ( D A B S ( D T H E T ) ) IF(Y(N)*X(N))183r184r184 2690 X21U78(03N0) = - 1 . 0 2710 G O TO 185 XU(N)=1.0 184 2720 Y7=2,0*(THET+ALPH*XU(N)) 2178350 Y8=DCOS(Y7) 2740 2750 Y l=Yb*Y8

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48115115b OOL9b45 268

3-266 2760 2770 2 780 2790 2800 281 0 2820 2830 2840 2850 2860 2870 2880 2890 2900 291 0 2920 2930 2940 2950 2960 2970 2980 299 0 3000 301 0 302 0 3030 3040 3050 3060 3070 3080 3090 31 00 3110 31 20 31 30 3140 31 50 31 60 3170 3180 3190 3200 321 0 3220 3230 3240 3250 3260 3270 3280 3290 3300 331 0

Aerodrome Design Manual OFELM=XL**2/8.0*~1.15*DABS~DTHET~*DIFF1+l.7*Yl*~DIFFl/2.OtDIFFO~O.5+ lO.S*S)) THET=THET+DTHET

1 8 6 FWHL=FWHL+FELM DFWHL (N)=FWHL 187 G O T O ( 1 8 8 r 1 8 8 r 1 8 8 r 1 9 2 ) r M O D E 1 8 8X F ( K o 2 ) 1 8 9 r 1 8 9 r 1 9 0 189 F(NrK)=FWHL G O TO 192 1 9 0I F ( K - S ) 1 9 1 r 1 9 1 r 1 9 2 1 9 1 F (NrK-2)SFWHL 192 C O U N T = F W H L * 1 0 0 0 0 . 0 / ( X L ) * * 2 DCOUNT ( N ) =COUNT IDCODE(N)=ICODE

FACC=FWHL+FACC I F ( M O D 1 .GT. 4 ) G O T O 196 G O TO (1968193r193r194),#0DE

193 X F(K-8) 196r196r194 194 W R I T E ( I O U T ~ ~ ~ ~ ) N ~ F W H L ~ I C O D E I C O D E ~ C O U N T 195 F O R M A T ( ' 'rlOXr'WHLe N O l ' r I 3 r S X r ' F ' r F 9 . 4 r 3 X r ' C O D E ' r 1 2 r 5 X r ' C O U ~ T ' r 1F7.1) 196 FWHLfO.0 FTOT=FTOT+FACC E(K)=FTOT

TOTCT=FTOT*10000.0/(XL)**2 I F ( M O D 1 .GT. 4 ) G O T O 200 G O TO (200r197r197r198)rMODE 1 9 7I F ( K - 8 ) 2 0 0 r 2 0 0 r 1 9 8 1 9 8 W R I T E ( IOUT0199) F T O T r T O T C T 1 9 9 F O R M A T ( ' ' r Z O X r ' T O T A L F'rF9.4r8Xn'TOTAL COUNT'rF7,1/) 200 G O TO ( 2 0 1 r 2 O l r 2 0 1 r 3 1 0 ) r M O D E 201 G O TO 202 X N M R + O e O DENOMZO.0 00207N=lrM AS=DSIN(Z.*BETA(N)) AC=DCOS(Z.*BETA(N)) I F( D A B S ( A S ) - ~ 0 0 0 ~ ~ 2 0 3 r 2 0 4 r 2 0 4 203 AS=O.O

204 I F ( D A B S ( A C ~ - r 0 0 0 1 ~ 2 0 5 r 2 0 6 r 2 0 6 205 AC=O.O 206 X N M R = X N M R - D A B S ( F ( N r I ) - F o ) * A S DENOM=DENOM+OABS(F(Nrl)~F(Nr2))*4C

207 C O N T I N U E IF(XNRR)209r208r209 208 ALPH=PIE/4.0*(1 .O+DSIGN(l.OrDENOM)) G O T O 212 209IF(DENOM)211r210r211 210 A L P H = . 5 * P I E * ( 1 . + . 5 * D S I G N ( l . r X N M R ) ) G O T O 212 211 A L P H ~ P I E / 4 . 0 * ( 1 ~ O + D S I G N ( 1 , O I D E N O M ) ) t ~ . 5 * O A T A N ~ X N M R / D E N O M ~ 212 ALPHD=18Or0*ALPH/PfE G O TO 2 1 5 213 CALL X Y M A X ( M r X L r E ( C ) r E ( 3 ) r E ( S ) r ~ r Y r Y M A X ) G O T O 215 214 CALL X Y M A X ( M r X L r E ( 7 ) r E ( 6 ) r E ( 8 ) n ~ r X r X M A X )

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0

3320 3330 3340 3350 3360 3370 3380 3390 3400 341 0 3420 3430 3440 3450 346 0 3470 3480 3490 3500 351 0 3520 3530 3540 3550 3560 3570 3580 3590 3600 361 0 3620 3630 3640 3650 3660 3670 3680 3690 3700 371 0 3720 3730 374 0 3750 3760 3770 3780 3790 3800 3 8 10 3820 3830 3840 3850 3860 3870

3-267

= K + 1 FTOT=O.O FACC=O.O G O TO 1 3 9

215 K

21 6 D0217N=1 r f l Y (N)=Y ( N ) - Y M A X

217 X ( N ) = X ( N ) - X M A X I F C M O D I ,GT. 4 .AND. I F (MODE-Z)218r232r232

ALPHD .GE,0,3)

GO

T O 240

218 STRS=6.0*Q*FTOT/D**2 ST(IN)=SiRS DX(IN)=D

IF(D-1Og0)2l9r219r222 219 I F ( S T R S - 6 2 0 . 0 ) 2 2 0 r 2 2 O r 2 2 1 2 2 0I N Z I N - 1 D = D / ~- 3 GO TO 1 2 8 2 2 I1L = I N

IN=8 D=13.0 G O TO 1 2 8 222 I F ( S T R S - 6 2 O S ) 2 2 4 r 2 2 4 r 2 2 3 2 2 3I L = I N 2 2 4I F ( S T R S - 2 8 0 . 0 )2 2 6 r 2 2 6 r 2 2 S 225 IN=IN+'l D = 1 .3*D G O TO 128 226 I H = I N IN=IL+l I O = D X (IN-1 ) D=I D D=D+1 ,O WRITE(IOUTr227) 2 2 7 F O R M A T ( ' ' / / I ' r 2 4 X r ' T H I C K N E S S' r 3 X r ' M A X . 228 R A = D L O G ( S T ( I N - ? ) / S T ( I N ) ) / . 2 6 2 3 6 3

STRESS')

RB=DLOG(ST(IN-1))+RA*DLOG(DX(IN-1)) STRS=DEXP(RB-RA*DLOG(D)) DO = D * XINCH STRSO = STRS / XPRES

WRITE(IOUTr229)DOrSTRSO 229 F O R M A T ( ' 'r25XrF5.lrF13.1) IF(STRS-280.0)310r31Or230 230 D=D+o -5 IF(D-DX(IN))228,228,231 2 3 1I N = I N + l I F( IN-IHI228rZ28r310 2 3 2I F ( A L P H D 1 2 3 3 r 2 3 4 r 2 3 4 233 ALPHD=180.0+ALPHD I F ( M O D 1 ,GT. 4 ) G O TO 240 234 W R I T E ( I O U T r 2 3 5 ) X M A X r Y M A X r A L P H D 235 F O R M A T ( ' ' r l O X r ' X M A X ' r F S . f r S X r ' Y ~ A X ' r F 5 . 1 ~ 3 X r ' M A X . 2 4 0 CONTINUE IF(MODE-3)250r310r310 2 5 0S T R S = 6 . 0 * Q * F T O T / D * * 2 C CONVERGE O N R E Q U I R E D THICKNESS.

ANGLE',F7,1/)

XINTRM=AREA*Q

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4110 4120 4 130 4140 4150 4160 4170 4 1 80 4190 4 200 421 0 4220 4230 4240 4250 4260 4270 4280 4290 4300

I F ( M O D 1 .EQ* 5 ) F C T N = X I N T R M * 4 0 3 . 0 / S T R S IF(MOD1 . E Q m 6 ) F C T N = X I N T R M * 398.85 / S T R S I F ( M O D 1 ,GT* 4)CALL C N V G ( * 1 1 1 8 r * 2 5 3 r F C T N t X I N T R M I DP M O D I , 260 I F ( M O D 1 ,LE. 4 ) G O T O 270 C W R I T E OUTPUTS(DELAYED UNTIL C O V V E ? G E N C E WAS COYPLETE). DO = D * XINCH XLO= XL * X I N C H WRITE(IOUTrll9) M O D I # SUBKOr D O WRITE(IOUTr137) XLO D C O U N T ( N ) r N=I,M) WRITE(IOUTr195)(NrDFWHL(N)rIDCODE(N)r W R I T E ( I O U T r l 9 9 ) F T O TTrO T C T W R I T E ( I O U T r 2 3 5 ) X M A XYr M A X / ALPHD 270 C O N T I NUE STRSO = STRS / XPRES WRITE(IOUTr28O)STRSO 280 F O R M A T ( ' ' , l O X , ' M A X m STRESS'rF7.I) C S A V E NUMBER O F I T E R A T I O N S R E Q U I R E D FOR C O N V E R G E N C E . I F ( M O D 1 .GT. 4 ) WRITE(IOUTr290) I T C T 290 F O R M A T ( ' + ' r 36X, ITERATIONS', IS) C C O M P U T E A N D W R I T E ACNI A N D R E T U R N T OS T A R T O F LOOP. 6 ) CALL C A C N C D r A C N r I S U B ) I F ( M O D 1 .EQ. 6 ) WRITE(IOUTr300) A C Y I F ( M O D 1 .EQ. 300 F O R M A T ( ' + ' , 57x1 'ACN', F6.lr // 1 31 0 X M A X = O . 0 YMAX=O.O I F ( M O D 1 .EQ. 6 ) G O T O 1117 IF(SPCFt)330r320r330 320 C O N T I N U E 330 I F ( M O D E - 3 ) 3 5 l 3 r 3 5 0 r 3 4 0 340 ALPHD=ALPHD+S,O ALPH=ALPHD/18OeO*PIE IF(ALPHD-AMAX)130rl3Or350 350JBS=JBS+1 WRITE(IOUTr360) 360 F O R M A T ( ' ' / / / / I IF(JOBS-JBS)370r370rlO2 370 C O N T I N U E C STOP END C

'

C C

4310 4320 4330 4340 4350 4360 4370 4380 4390 4400

m

Aerodrome Design Manual

3-268 3880 389 0 3900 391 0 3920 3930 3940 3950 3960 3970 3980 3990 4000 401 0 4020 4030 4040 4050 4060 4070 4 080 4090 4100

030

SUBROUTINE PARAE ( A r B r C r D t S r X L r G ) DOUBLE P R E C I S I O N AIB~CIDIGIXL G=D+((A-B)/(2.*C-A-B)+2m*S)*.025*XL RETURN END

C C C

4410 4420 4430

25/10/85

NO. I .

S U B R O U T I N E X Y M A X (MIXLIB~A~C~KIYIYMAX) D I M E N S I O N Y (20) DOUBLE P R E C I S I O N A~AB~B,CIYPYYAXRXL GO TO ( 2 3 0 ~ 2 1 5 r 2 1 5 r 2 1 7 ~ 2 2 0 ~ 2 1 5 ~ 2 1 7 ~ 2 2 0 ~ ~ K 2 1 5 D0216N=lrM

ITCT)

Part 3. - Pavements 4440 4450 4460 4470 4480 4490 4500 4510 4520 4530 4540 4550 4560 4570 4580 4590 4600 4610 4620 4630 4640 4650 4660 4670 4680 4690 4700 4710 4720 4730 4740 4750 4760 4770 4780 4790 4800 4810 4820 4830 4840 4850 4 860 4870 4880 4890 4900 4910 4920 4930 4940 4950 4960 4970 4980 4990

3-269

2 1 6 Y (N)=Y(N)-XL/ZO.O G O T3 2 3 0 2 1 7I F ( B - A ) 2 1 8 r 2 1 5 r 2 1 5 21D 8 0219N=l,M 2 1 9 Y (N)=Y (N)+XL/10.0 GO TO 2 3 0 2 2 0I F ( Y ( 1 ) ) 2 2 1 , 2 2 6 r 2 2 6 2 2I 1F ( 2 . * 8 - A - C ) 2 2 2 1 2 2 2 , 2 2 3 2 2 2 A=B B=C

K=K-1 GO TO 215 2 2C 3 A LP L ARAB (A,C~BIY(~),~.OIXLIYM~X) 2 2 4 AB=Y ( 1 ) DO2 25N = l rM 2 2 5 Y (N)=Y(N)+YMAX-AB GO TO 230 2 2 I6F ( 2 . * A - B - C ) 2 2 7 , 2 2 7 , 2 2 9 2 2 7 D O 228N=l,M 2 2 8Y ( N ) = Y ( N ) + X L / Z o . o A=C

B=A K=K-I GO T O 2 3 0 229 CALL PARAB GO TO 2 2 4 2 3 0C O N T I N U E RETURN END

10 20 30

40 .

(C,BIAIY(~),-~,OIXLIYMAX)

THICKNESS, S U B R O U T I N E C N V G CONVERGES ON REFERENCE SUBROUTINE CNVG( * I * t FCTN, T R G T e Y111, MODI, ITCT ) DOUBLE P R E C I S I O N FCTNITRGTIYI 1l r Y 2 2 2 1 Y 3 3 3 r X 2 2 2 1 X 3 3 3 I F C I T C T ,EQ. 0 G TO 30 rTCT = ITCT + 1 I F ( 1 T C T ,GT. 2 0 1 GO T O 4 0 I F ( D A B S ( ( F C T N - T R G T/ )T R G T. )L T . 0,0001 ) GO TO 4 0 IFCFCTN .Gt. TRGT 1 GO TO 1 0 Y222 = Y l l l X 2 2 2 = FCTN G O TO 2 0 Y333 = Y l l l X333 = F C T N Y l l l = Y222 + (Y333 Y222) * (TRGT x2221 / (X333 RETURN 1 ITCT = 1 Y 2 2 2 = 0.0 x 2 2 2 = 0.0 Y333' = Y l l l X 3 3 3 = FCTN G O TO 2 0 C 0N.T IN U € RETURN 2 END

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3-270

.~

5000 501 0 5020 5030 5040 5050 5 060 5070 5080 5 090 5 1 00 5110 5120 5 1 30 5140 5150 5160 51 7 0 5180 5190 5200 521 0 5220 5230 5240 5250 5260 5270 5280 5290 5300 531 0 5320 5330 5340 5350

C C C

No. 1

i I

C

S U B R O U T I N E C A C N CALCULATES A C N ' S F O R FOUR S T A N D A R D S U B G R A D E S . S U B R O U T I N E C A C N ( Dr A C N r I S U B 1 D I M E N S I O N DACN(6r4) DOUBLE P R E C I S I O N D A C N ~ D I S S W ~ A C N D A T AD A C N /-a367886361D+Olr-.3533157820+021'3.246548051 D+03r (1 0 . 5 3 7 9 2 6 9 2 6 D t O l r -.141694493D+08r 8 -.899203216D+OOr -.414577103D+02. 8 0 ~ 6 6 6 3 2 0 1 5 3 D + O l r -.180481030D+03r & 0.2342931 79D+OIr -.529631013D+O?r 8 Omt3033983850+01r -.209875377D+OO, 8 OO139960077D+02r -.854754059D+02r 8 O1825962325D+01r -.1500194270+05r

8.190408260D-021 le2638319750+03r 1.256828585D-32r 3.28521 7274D+03r Oa305236166D-921 3.319839693D+03r I. 153530363D-02 /

SSW = D A C N ( 1 r I S U B ) D O 1210 I A C N 2r6 SSW = SSW + D A C N ( 1 A C N r I S U B ) * D * * ( I A C N - l ) 1210 CONTINUE / 1000.0 / 2.20452 ACN = S S W * 2.0 1260 RETURN END S U B R O U T I N E RSUBK(SUBKrSUBK0) D I M E N S I O N S U B K I ( 7 ) rS U B K I I ( 7 ) COMMON I O U T DATA S U B K 1 / 2 0 . r 2 5 . r 4 0 . r b O . r 8 ~ ~ r 1 2 ~ . ~ 1 5 ~ . / DATA DO 10 N S A V E = 1 8 7 I F ( S U B K O = S U B K I ( N S A V E ) ) G O T O 20 1 0 CONTINUE

WRITE(IOUTr50)SUBKO

s TOP 20 S U B K

=:

SUBKII(NSAVE)

RETURN

5 0 F O R M A T ( 1 H ~ r ' I N V A L I D S U E K 'rF17.2) END

I C A O 9357 P A R T t 3 tt

=

4 A 4 1 4 3 b 0039650 625

Computer Programme No. 2

1. The computer programme o r i g i n a t e d by t h e Boeing Co-mpany, a nf ud r t h e r developed by t h e U n i t e d States Army Engineer WaterwaysExperiment S t a t i o n (USAEWES) f o r c a l c u l a t i n g f l e x i b l e pavement t h i c k n e s s r e q u i r e m e n t s h a s b e e n m o d i f i e d by McDonnell Douglas t o c a l c u l a t e f l e x i b l e pavement A i r c r a f t C l a s s i f i c a t i o n Number (ACN) values. The changes to t h e USAEWES computer programme, as p u b l i s h e d i n R e p o r t S-77-1, were e x t e n s i v e ,a n di n c l u d e dc h a n g i n gt h ei n p u ts y s t e mf r o mt i m e - s h a r i n g - o p t i o n to b a t c h I B M 370 system,adding s y s t e m ,c h a n g i n gt h eo u t p u ts t a t e m e n t st ob ec o m p a t i b l ew i t ht h e code t o calculate ACN v a l u e s andadding a s u b r o u t i n e "CVRG" t o convergeon t h e r e q u i r e d pavementthickness. 2. It w i l l bneo t et d h tahtoeu t p u t of t h e McDonnell Douglas modification d i f f e r s s l i g h t l y fromtheReport S-77-1 w i t h r e s p e c t t o t h e C o v e r a g e s a n d t h e Alpha d a t a . The r e a s o n i s t h a t t h e McDonnellDouglas m o d i f i c a t i o n sets t h e f i r s t Coverages v a l u e t o 10 000, a n di g n o r e sa n yo t h e ri n p u t s . It also sets t h e f i r s t A l p h av a l u et o is t h e v a l u e of F i g u r e1 4 of Report S-77-1, a n di g n o r e sa n yo t h e r Alpha v a l u e s .T h i s d o n e( r e g a r d l e s so f w h a t v a l u e s are i n p u t ) b e c a u s e t h e d e f i n i t i o n of ACN f o r f l e x i b l e pavements i s based on 10 000 coverages,andthecorrespondingAlphavalue. A copyof F i g u r e 1 4 ofReport S-77-1, a p l o t of t h e Alpha v a l u e s (Load R e p e t i t i o n F a c t o r ) , is reproduced as F i g u r e A2-4.

3. The p r o c e d u rfecosar l c u l a t i nCgB R I t h i c k n eds es s i gc n u r vaens d -ACN of aircraft have been computerized with the exception of the pass-per-coverage ratios. D e t a i l e d b e l o w are a n i n p u t g u i d e , a n i n p u t f i l e , a problemoutput,and a programme l i s t i n gf o rt h e s ep r o c e d u r e s . The problemoutputs are f o r t h e C-14lA. The b a s i c d a t a f o r t h e

C - 1 4 U are:

A i gr cr o r as fst

mass

kg 152 = 145

P e r c e n t a g e mass onmaingearlegs

= 90

Number legs gear main of

= 2

T i r e pressure

= 119 kPa

Number of w h e e l s u n d e r c o n s i d e r a t i o n

= 4

T i r e spacing

= 82.55 121.92 c m by

(See Figure

8 '->

.

.

..

cm.

A2-3)

3-272

A e r o d r m e Design Manual

Otherrequireddataare: P a s sl e v e l s

= 1-7 p a s s levels as s e l e c t e d .

Alpha v a l u e s = 1-7 a l p h a v a l u e s c o r r e s p o n d i n g t o t h e s e l e c t e d p a s s are o b t a i n e d from F i g u r e A2-4.

levels

Grid location and dimensions = The g r i d i s used in t h e s e a r c h for t h e p o s i t i o n of maximum d e f l e c t i o n for E W L c a l c u l a t i o n s . L o c a t i o n of t h e g r i d may be a t r i a l - a n d - e r r o r p r o c e d u r e f o r a p a r t i c u l a rg e a r ,a l t h o u g h ,w i t he x p e r i e n c e ,t h i s location can be determined by good engineering judgement. The v a l u e s o f GX and GY r e p r e s e n t t h e X-Y o r i g i n of t h e g r i d , DGX and DGY t h e d i s t a n c e betwen g r i d l i n e s , a n d XK and YK t h e number of g r i d l i n e s i n e a c h d i r e c t i o n . is shown in Figure A2-3. The g r i d used i n the sample problem Normally, t h e d i m e n s i o n s b e t w e e n g r i d l i n e s s h o u l d bo i n t h e o r d e r of 112 r a d i i . Theradius of t h e tire c o n t a c t area assumes t h e area t o be a circle and, f o r t h i s example, is c a l c u l a t e d as follows:

ICAO 9357 P A R T S 3

1

f f

4 6 4 3 4 3 6 0037652 4 T B

3-2 7 3

P a r t 3 . - Pavements

Y-AX IS

1

X-AXIS

+-- 82 55 .-4 a.

{

W H E E L CONFIGURATlON, COORDINATES

GRID LOCATION

X- DATA GX=O.

D G X = 10.32 X K = 5.

4 . -

b. -

GRID

DIMENSIONS

F i g u r e A2-3.

2S/lO/S5 No. 1

COORDINATES

C-141A g e a r and g r i d

Y - DATA GY = 0. DGY

=15.24

YK=5.

3-274

I C A O 9357 P A R T * 3

** W 4B4LL(Lb 0059b53 3 3 4

m

Aerodrome Design Manual

25/10/85 No. 1

BATCH MODE INPUTGUIDE FOR ACNCOMPUTER PROGRAMME FOR FLEXIBLE PAVEMENT ( u n i t s are kilograms and c e n t i m e t r e s )

t

TITLE - - - ALPHABETICANDNUMERIC CHARACTERS MAY BE USED IN ANY OF THE 80 COLUMNS. THIS CARD ALSO MAY BE BLANK, BUT MUST BE PRESENT. 1 23456789

10 11 12 13 14 15 16 17 18 19 20212223242526

27 282930 31 3233343536

37 383940 41 42434445

46 47 4849 50 51 52 53 54 5556 57 58 59 60 79 80

COLUMN20. FOR MODE GREATER THAN 10, PROGRAMME FINDS DEPTHS FOR DESIRED CBRs. RD SUBGRADES. FOR MODE

3 X-COORDINATE FOR EACH WHEEL (32MAXIMUM). 1 234567

14

USEADDITIONAL CARDS AS REQUIRED.

8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 242526 27 2829 30 31 32 33 343536 37 383940 41 42 43444546474849

Y-COORDINATE FOR EACH WHEEL (32 MAXIMUM).USE 1 234

5 6 7 89

59 60

ADDITIONAL CARDS AS REQUIRED.

10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 I

50 51 52535455565758

27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 I

I

F i g u r e A2-5.

I

Sample i n p u t s C-14l.A

d

1 1 1 79 80

50 51 52 53 54 55 56 57 58 59 60 I

79 80

6

NUMBER (M) OFDEPTHS

FOR MODE LESSTHAN 11, PROGRAMMESETSDEPTHSTO

DELTA I W T H

1 2 3 4 5 6 7 8 9 1011 1213141516171819M

Illlfllil.

(N X DELTA).

(N = 0, 1, 2,..,M-I),

(MAXIMUM M IS 8). FORMODEGREATERTHAN 10, PROGRAMME FINDS DEPTHSFOR DESIREDCBRs. FOR MODEGREATER THAN IO, THIS CARDI~AAY BE BLANK.

I I I I I I I e l I

7 NUMBER (K) OF SETSNUMBER

(K) OF SETSOFAIRCRAFTDATATOFOLLOW.

i

)8)

AIRCRAFT MASS

I

TIRE PRESSURE (kPa)

I

PER CENT

MASS

ON MAIN GEAR LEGS

Figure AZ-5.

I

MAIN NUMBER GEAR OF LEGS

I

~~~~

~

ONECARD FOR EACHSET OF A'RCRAFT

Sample i n p u t s C-141A (cont .)

~

NUMBER (J) NUMBER OF LEVELS PROGRAMME

9

~

~~~~~~~~~

~

~~

~

~

~

~~~

(J) OF PASS LEVELS OR COVERAGE LEVELS. (MAXIMUM J = 7). FOR MODE EQUAL 11, SETS J = 1.

PASSLEVELS OR COVERAGE LEVELS (JLEVELS).ADJUST EACH INPUT TO THEEXTREME RIGHT. FOR MODE EQUAL 11, PROGRAMME SETS FIRSTLEVEL TO 10.000.fNOT USED IN COMPUTATIONS.) 3456

7 89

111 ALPHA VALUES

10 11 1213 14 15

FOR LEVELS PASS

OR COVERAGE ALPHA VALUES). LEVELS (J

PROGRAMME,SETS FIRST ALPHA VALUE 1 2 3 456789

I

11,

TO 10,000 COVERAGE VALUE FOR INPUT NUMBER OF WHEELS.

10 11 12 13 14 15 16 17 18 19 20212223242526272829 I

~

FOR EQUAL MODE

30 31 32 33 34 35 36 37 38 39 40 41 42 434445 I

46 47 48 49 50 51 52 53 54 55 56 57 58 I

~~~

21 DESIRED CBRs. MAXIMUM OF 4. FOR MODE EQUAL 11, PROGRAMME SETSTHESTANDARD SUBGRADE CBRs. FOR MODE LESSTHAN 11, PROGRAMMEFINDSCBRs 1 2 3 4 5 6 7 8 9 1 0

24 25 26 27 28 29

30 31 32

FOR INPUT DEPTHS. 33 34 35 36

37 38 39

I

40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 I

57 58 59

1 1 1 1 l l l l l l 1 1 1 1 l / l l l 1 l l l l l l l o l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l l lW 0

0

0

F i g u r e A2-5.

Sample i n p u t s C-141A ( c o n t . )

ICAO 955’7 P A R T * 3 3-278

**

4 S 4 5 4 5 b 0059b57 T A T

Aerodrome Desim Manual

.

SAEPLE INPUTS L O C K H E ED

C 1 4 1A

11 82.55 0.0 10.32.

4

0.00 O m 00 .

0,o

~

1 1 4 5 1 52. 1 10000

1190.

50000

a2.55 121.92 5 m0

90

.

O m

CO

121.92

0.

c

15.24

2.

1or3000

0.825

SAMPLE OUTPUTS LOCKHEED

C 1 41 A

N U M B E R O F W (HMEAEXL ISM U M 4 .-X C O O R D I N A T E S OF- W H E E L S 0.00 82-55 82.55 Y C O O R D I N A T E S OF W H E E L S

0.00

0.00

L O C O OF GRDIGRD 0.00 10.32 N U M B E R O F DEP.

0.00

32)

MODE 11

Os00

121.92

121.92 tJ0. O F L I N S ( H A X ( 1 0 ) ) 5.00 0.00 15.24 5.00 (M-AX -cg) A N D E PI .N C R E M E N T INCRTI

0.00

OF S E T S OF M A SA SND TYRP ERESSURE 1 AIRCRAFT MASS

NO.

145152.00

-

-

. _. -T Y--,R EP R E S S U R E

Il90.0b

PERCENM T ASS

Il90.0b

1190.00 11

90.00

O N M A I NG E A R

90.00

.

R A D I U S O F T Y RC E O N T A C AT R E A 20.71 20.71 20.71 -P A S S E S OR C O V E R A G E S

20.71

10000

A L P H AV A L U E SM A X

(7)

0.825 DESIRED CBR

3.00

25/10/85

No. 1

6 -00

10.00

15.00

5.

ICAO 9357 P A R T * 3 t t

LIBLILLILb 0039658 9 L b

Part 3.- Pavements

a

1-779

SAMPLE OUTPUTS (cont. ) -TD E P TPHA S S E SE S W L KG

C BR

10000

CM

0.00 143.53

294.32 3.00

20955. 52429.

._

A

TH AE C FN OR

SUBGRAD CE BR

CBH DPE.kPSTE SHfEWS t KG

TH A EC N

294.32 6.00

FOR

A

.

T HAEC N

FOR

SUBGRAD CE BR

294.32 10.00

A

20955. 28080.

T H E ACN FOR

4d.00

OF 1 5 IS

41.93

-T-

CM

0 000 60.12

S U B G R A DCEBORF

1 ouoo 294.32 15.00

A

10 I S

OF

-

- TC B R D E P TPHA S S E S ESWL KG

59.30

0.00 89.08

10300

2095 5 . 32675

6 IS

CM

C BR D E P TPHA S S E SE S W L KG

73.53

-T-

. .

10000

2095 5 . 41313.

3 IS

OF

S U B G R A DCEB R

CM

0.00 43.94

25/10/85 No. 1 .~

I C A O 9357 P A R T 8 3

3-280

*Kt

W 4 8 4 3 4 5 6 0039659 852

m

Aerodrome Design M a n u a l

.

PROGRAMME L I S T I N G COMPUTER PROGRAMME

NO.

2

FLEXIBLE PAVEMENT ACN 10

20 30 40

50

P R O G R A MA C N F I T

c C C

c

A C60 t J / P CCN 70 C 80 C 90 C 100 c 110 c

120

c

130

C C C C C C

140

150 160 170 180 190

200 210

220 230 240

250

260 270 280

290

.ooo

300 310 320 330 340 350

c c c c

C C C C C C C

c

390

C C C C C C C C C C

a000 410

C

420

C

430

C

360 370

380

c

,000 450 460 470 480 490

500

c

25/10/95 NO. 1

P R O G R A HA C N F II SI NI N T U. N I T S ECN V A L U E FS O R STANDARD A P R I L 1979 M O D I F I C A T I O N TO COHPUTA SUBGRADES

********* 1 WAR 6 9 WES M O D 41-62-R0-144 PROG. 4 1 - 2 0 - 0G0R1 O U FNLDO T 4 T ID3 ENS I G N D O C U M E N0 6T - 4 0 8 8 TT NR A N S P O RD TI V I S I O N r

* * * B O E I ANIGR C R A F T B O X 7 0 7 r R E N T OWNAt S H .

TO T H O ER I G I N BA O L E I NP G ? 3 G R TA H P# A EVEMED NE TSIGN NOTE D I V I S I O NSr + P LWr E SHr A M S A D SE E V E R ACL H A N G E ST.H TEH I C K N E S S S O L U T I O NU A SR E P L A C E DW I T HA NI N T E R P O L A T I O NS C H E M ET. H E T H I C K N E S SI S NOU D E R I V E FD R O M CB?/D VS. T / S Q R ( AC) U R V E . T H EO L DF t P E R C E N TD E S I G NT H I C K N E S S H) A SB E E NR E P L A C E D WITH AN ALPHA V A L U ET. H E TERM COVERASES IS REPLACED WITH P A S LS E V E L S . THIP SROGRAM ' C H A N G 4I 'ISD E N T I C A TL O 'CHANGZ' TO R U N 1-7 W I T HO N EE X C E P T I O NA. NO P T I O NI SA V A I L A B L E P A S LSE V E L S .

32

NN

NUMBER OF WHEELS X (NW) X COORDINATE CM Y (NW) Y COORDINATE Cbl 32 RRAADD( N Y ) C H IU S 32 SR Q AUUDARSZRA(EN DDU 1) 32 P R (NU 1 P3ES SURE 32 KPA PIESSURE PRS(NW) GX X COORD O F G R I D D ( DE1LDSTGPAXL . C ) X Y COORD OF G R I D ( D IES DLPGTLYAC 1 Y GX X K = KNXU M B EGRR ILDI N K( SS I Z E ) YKZKY N U M B E GR R I LDI N K S (SIZE) ZKZKZ NUMBER OF D E P T H S 1o* AN PUG HS ILf D E I N INTEGRATION 1o* cs C O S I N E 3F P H I 1o* SN2 S Q O F S I N E OF P H I 1 O ~S l( OI Drr JI8 Sr KP )L A C E M E N T 6 KK Z N U M B E R O F MAX. 3 R DDE IRSEPDL A C E M E N O F M A SASNTDY S3ER E S S U R E I PNRU M B ESRE T S 5 cCVOA VL EJ ER AI TGHE 8 z D E P T H dOF H E EI LT H 8 SQ zU 2 A R E DZ ( 1 ) COMMON X ( 3 2 ) r Y t 3 2 ) r R A D ( 3 2 > ~ R A D ~ ( 3 Z ) , P R ( 3 2 ) , P R S ( 3 2 ) COMMON X G ( I O ) r Y G ~ 1 0 ) r S ( l O r l O r 3 ~ ) COMMON Z ( 3 0 ) / Z 2 ( 3 0 ) r X L O C ( 3 0 r 6 l r Y ~ ~ C ( 3 0 r 5 ) r S D ( 3 0 r 6 ) COMMON C C S ) r E S U L ( 3 0 ) r C B R ( 3 0 / 7 ) COMMON S N 2 ( 1 0 ) r C S ( 1 0 ) D I M E N S I O NK T I T L E ( 2 0 )

32 32

CM CM CM

CM MPA

TS /DEPTH

I C A O 9357 P A R T * 3

I

Part 3 . - Pavements

**

484L4Lb 0039bbO 5 7 4 W 3-281

000 520 530 000 550 560 570 580 590 600 61 0 620 63 0 640 650 660 67 0 680 690 700 71 0 72 0 73 0 740 75 0 760 77 0 78 0 790 800 a1 o 820 830 84 0 85 0 86 0 870 88 0 89 0 900 91 0 92 0 930 940 950 96 0 97 0 980 99 0 1000 1010 1020 1030 1040 1050 ,000

0

.

I'

25/10/85 No. 1 .

I

ICAO 9357 P A R T * 3 3-282 0

000

.

,000 000

1100

1110 1120 1130 1140 1150 1160 1170 1180 11 9 0 1200 1210 1220 1230

1240 1250

0000 1270 1280

000

1300 1310

0000 1330 1340 0

000

1360 1370 1380 1390 1400

IO00 1410

0000 1430 1440 0

YBY145b OO39bb3 400 W Aerodrome Design Manual

.

0000

0

**

000

.

1450

000

1460 1470 1480 1490 1500

1510

910 FORMAT(1H r l 3 H A I R C R A F T MASS/(9F11 . 2 ) ) 911 F O R M A T ( 1 H rl3HTYREPRESSURE/(9F1l02)> 950 FORMAT(1H r 2 5 H P E H C E N T M A S S ON H A I N GEAR/(9F8.2)) 912 FORMAT(1H r27HRADIUS OF T Y R E C O N T A C T AREA/(9F8.2)) 913 FORMAT(1H r 2 0 H P A S S E S O R C O V E R A G E S / r 7 1 1 0 > 914 F O R M A T ( 4 X r ' D E P T H ' r C X # ' D E F . ' r 4 X r ' X - C R D . ' r 3 X r ' Y = C R D . + ~XI'DEPTH'I~XI'DEF.'~~XI'X-CRD.'~~X~'Y-CRD.'~ + 5x1' CR ' r 3 X # ' F A C T O R ' r 4 X r ' c # ' r 5 X r ' CPI + 4x1' C M 'r3X,'FACTOR'r4X,' C# ' ~ 5 x 1 ' C q ' 1 915 F O R M A T ~ F 9 ~ l r F 9 ~ 3 r F 9 0 2 r F 9 0 2 r F 9 0 1 r FF9.2rF9.2/ 9~3r +(F1803rF9.2rF902rF18.3rF9.2/F9.2rF902)) 916 F O R M A T ~ F 9 ~ l r F 9 ~ 3 r F 9 . ~ ~ F 9 0 ~ / ~ F 1 8 0 ~ r F 9 0 2 r F 9 ~ 2 ~ ~

'I

5

F O R M A T ( ~ ~ X ~ ~ H C B R ~ ~ X I ~ H C B R ~ ~ X ~ ~ H C ~ R ~ ~ X ~ ~ H C B R ~ ~ X ~ ~ H C 7Xr3H-T-r/r4Xr4HESWLI5XI6HPASSESI4X16HPASSESr4Xr6HPASSESr4Xr6HPASSESr4Xr + ~ H P A S S E S I ~ X P ~ H P A S S E S ~ ~ X ~ ~ H D E P T H PKG / , ~ X/ 1~1~0Hr I 1 0 r I 1 0 r

+

+ 1 1 0 r I l O r 6 X r 3 H C Mr / r F 9 0 O r 6 F 1 0 , 2 ) 925 % O R M A T ( l H rl9HALPHA VALUES MAX(7)./r(7F1013)) 927 TORMAT(1H r l l H D E S I R E D CBRr / F1002rF10.2rF10.2rF10.2) I FORMAT(1H r I S X r 3 H C B R r 7 X r 3 H o T - r / r 4 x r 4 H E S U L 1 5 X 1 6 H P A S S E S r S X 0 S H D E P ~ H ~ + /r3Xr6H KG rIIOr6Xr3HCM 0 + /r30(/rF9.012F10,2)//) 2 FORMAT(1H ~ ~ ~ X ~ ~ H C B R ~ ~ X ~ ~ H C ~ R I ~ X ~ ~ H - T - ~ / ~ ~ X ~ ~ H E S W L ~ + ~ X I ~ H P A S S E S I ~ X ~ S H D E P T H ~ / ~ ~K GX # ~r Z H IIOr6Xr3HCH I + /r30(/rF9,0r3FI0,2)//)

3 FORHAT(1H r 1 S X r 3 H C ~ R r 7 X r O H C 8 R r 7 X r 3 ~ C 3 R r 7 X r 3 H ~ T - r / ~ 4 X r 4 ~ E S W L ~ l X r + ~ ( ~ X ~ ~ H P A S S E S ) ~ S X P ~ H D E P T HK ~G / ~ r3110r6Xr3HCM X I ~ H I + /r30(/rF9,0~4F1002)//) 4 FORMAT(1H ~ ~ ~ X ~ ~ H C B R ~ ~ X ~ ~ H C B R I ~ X ~ ~ H C B R ~ ~ X ~ ~ H C B R ~ + ~ H E S W L ~ ~ X ~ ~ ( ~ X ~ ~ H P A S S E S ) ~ ~ X ~ ~ KHG D Er411016Xr3HCH P T H ~ / ~ ~ X Hr ~ H + /r30(/rF9.0rSFI0.2)//) 940 FORMAT(8ElU.O) 941 FORMAT(BI10) X INCH=2 5 4 XPRES=145.0377438 X P O M D ~2.2046225 PI=3.1415926535898 10 CONTINUE ( C A R D TYPE '1') R E A D CURRENT T I T L E C A R D R E A D ( 5 r l S r END=6000) KTITLE 15 FORMAT(2OA4) ( C A R D TYPE ' 2 ' ) READ(Sr941)NWrMODE ( C A R D TYPE ' 3 ' ) IF(NWmGT,7)G0 T O 20 READ(5194o)(X(l)rI=lr~W) GO TO 30 20 C O N T I N U E READ(51940)(X(I)rI=lr8) IF(NW.LT.9)GO T O 40

.

1520

READ(5r940)(X(I)rI=9rl6)

1530

I F ( N Y o L T o 1 7 ) G 0 T O 40 READ(Sr94O)(X(I)rI~17r24) IF(NU.LT.25)GO TO 40

1540

1550 1560 1570

000

25/10/85 No. I.

READ(5r940)(X(I)rII2Sr32) G O TO 4 0 (CARD

TYPE

'4')

I C A O 7357 P A R T S 3

I

**

m

4 8 4 3 4 3 6 0037662 347

m

Part 3 . - Pavements

a

30 R E A D ( 5 r 9 4 0 ) ( Y ( I ) r I = I r N W )

1580 1590

G TOO 50 4 0R E A D ( 5 , 9 4 0 ) ( Y ( I ) r I = 1 . 8 ) IF(NW.LT-9)GO TO 50 READ(5#940)(Y(I)rI=9.16) I F ( N d . L T . 1 i ' ) G TOO 50 READ(5,940)(Y(I),I=17r24) IF(NW.LT.25)GO TO 50

1600 161 0 1620 1630 1640 1650

1660 1670 1680 -000 1690 1700 171 0 1720 1730 1740 1750 1760 1770 1780 000 1800 1810 18 2 0 1 830 18 4 0 18 5 0 1 860 1870 1 880 1890 000 191 0 19 2 0 19 3 0 19 4 0

READ(Sr94O)(Y(I)rI=25#32) 50 C O N T I N U E C

.ooo

,000 1950 1960

-000 -000

.ooo

..ooo ..0 0 0 000

000

IO00 ,0 0 0

.ooo

.000

IO00 2000 201 0

READ

I N G R I D I S P L A C E M E N T I I N C R E M E N AT N D S I Z FE O R

c C

60

R E A D ( ~ , ~ ~ O ) G X I D G X ~ X K I G Y I D I F T HNEU M B E R OF LINES (XK OR I F (X K .GT. ZERO) GO TO 70 X M A X = 0.0 D O 6 0 M A X X = IINW I F X( C M A X X ) .GT. X M A XX)N A X = CONTINUE G X = 0.0 XK=10.0 G X ) /2.0 / (XK-1 DGX= ( XMAX I F Y( K .GT. Z E RGTOO 90 Y M A X = 0.0 D O 80 M A X Y = I r N W I F Y( C M A X Y ) ,GT, Y M A XY)M A X = C ONT I N U E G Y = 0.0 Y K = 10.0 D G Y = ( Y M A X - G Y/ Z) , O / ( X K - I . O > CONTINUE K X = XK K Y = YK REA ND UMBE O DR E FPTH AN S DD E P ITNHC R E M E (NCTA R TY DP E R E A D ( 5 r 9 4 0 Z) K l D Z KZ=ZK M =O

-

.

.

3-283

70

80

90

c

C

**************

c c

R E A D NO.

c c

OF

SETS

OF

X A N YD - A X I S '5') (CARD TYPE

G Y ~ Y K Y K ) I S N OI TN P U T I S EDTE F A U L T S .

X(4AXX)

.O)

Y(MAXY)

'6')

M A S S # T Y RPER E S S ,M# A SOSM N A IG N E A RN# O . OLFE G S ( C A R TD Y P E

R E A D ( 5,941 ) I P R =I/ IPR D O4 5 0 0I P R S READ AIRCRAFM T ASSeTYRE P R E S S . Y# A S S

ON M A I NG E A R # NO,OF ( C A R TD Y P E

'7') LEGS

'8')

R E A D ( S r 9 4 0A )M A S S ~ P R S W I P M M G I A M L G WT=AMASS*9,8f5/1000.0 TLMG=WT*PMMG/100.0 TLSMG=TLMG/AMLG W N = NW TLSW=TLSMG/WN ARESW=TLSW*lOOOO.O/PRSW RESW=SQRT(ARESW/PI) PESW=PRSW/1000.0 C A R E A = RESW * RESW * P I RESW2 = RESW * RESW CAREA=CAREA/(XINCH*XINCH)

25110185 No. 1

ICAO 9357 P A R T M 3 '

3-284

IO00 204 0 2050 100

.. .. .OOO .. .

000 000 000 000 110

000 000 000 t 000 000 000 2070 2080

.ooo

,000

.

41145436 0 0 5 9 b b 3 283 Aerodrome Design M a n u a l

.

2020 2030

..

**

RESWi?=RESW2/(XINCH*XINCH) D O 100 I ' l r N W PRS(f)=PRSW P R ( 1 ) = PESW R A D C I ) = RESW IF(IPRS.EQ.1) G O T O 120 D O 110 I o l r N W X ( I ) = X ( I ) * XINCH Y ( f ) = Y ( 1 ) * XINCH CONTINUE GX = GX XINCH DGX DGX * X I N C H GY = GY * XINCH DGY D6Y * X I N C H DZ = DZ * XINCH

*

TO 1 5 0 F O R ACN CALCULATIONS ONLY T H E R E A D NO. O F P A S S LEVELS.

GO C C

c

10000 C O V E R A G E VALUE (CARD

R E A D ( 5 r 9 4 1 ) NAL 2100 IF( MODE .EQ.II) NAL=I .ooo c R E A D PASSES. 2120 READ(Sr941)(NCC(I)rI=Ir~AL) 21 30 I F C M O D E .EQ. 1 1 ) NCC(1) = 1 0 0 0 0 R E A D ALPHA'S ,000 C 2150 READ(5/94O)(B(I)rI=lrNAL) 2160 C F O R ACN CALCULATIONS S E T F I R S T ALPHI\ 21 70 I F ( M O D E .NE, 1 1 ) G O TO 130 I F ( NW . E Q . 1) B ( 1 ) = 0.995 2180 2 1 90 I F ( N W .Ea, 2) B ( 1 ) = 0.9 2200 I F ( NW . E Q . 4 ) E l ( ? ) = 0.825 221 0 I F ( N U .EQ. 6) B ( 1 ) 0.788 2220 I F ( NW .EQ. 8) B ( 1 ) = 0.755 2230 I F ( N W .EQ,12) B ( 1 ) = 0.722 2240 IF( N W .EQ,18S B ( 1 ) = 0.700 2250 I F ( NW .EQ.24) B ( 1 ) 0 0.689 2260 N C C ( 1 ) = 10000.0 2270 130 C O N T I N U E R E A D CBR D E S I R E D ( T A R G E T ) -000 c 2290 READ(Sr940)(SCBR(I)rI=Ir4) 2300 I F ( M O D E .NE. 1 1 ) GO T O 140 231 0 S C B R ( 1 ) = 3.0 2320 S C B R ( 2 ) :: 6.0 2330 SCBR(3) = 10.0 2340 SCBR(4) = 15.0 2350 140 C O N T I N U E 000 150 WRITE(6r9001 2380 WRITE (68901 1 2390 WRITE(6r902)KTITLE iJRITE ( 6 ~ 9 0 3 ) N W r M O D E 2400 241 0 W R I T E ( 6 r 9 0 4()X ( 1 ) r I S l r N U ) 2420 WRITE(br905) ( Y ( I Y r E * ? r N W ) f430 WRITE(6r906) G X r D G X r X K r G Y r D G Y r Y K 000 I F f I P R S . N E . 1 ~ G O TO 760 2440 WRITE(br9072 Z K r D Z 0 000 '1-60W R I T E ( 6 ~ 9 0 9 ) I P R

I S USED. TYPE

'9')

120

.

25/10/8-5 No. 1

( C A R D TYPE

'19')

( C A R D TYPE

'11')

T O 10000 C O V E R A G E VALUE.

(CARD

TYPE

'12')

P a r t 3 . - Pavements

IO00 2470 000 2480 2490 2 500 2510 2520 2530 2540 2550 2560 2570 2580 2590 2600 2610 2620 2630 2640 2660

.

1000 0000 000 2680 2690 2700 2710 2720 2730 2740 2750 2760 2770 2780 2790 2800 281o 2820 2 a30 2840 2850 2 860 2870 2880 2890 2900 2910 2920 2930 2940 295 0 2960 2970 2980 2990 0

3-285

WRITE (68910) AMASS WRITEC6r911) (PRS(I)rI=l,NW) W R I T E (6,950) PMMG WRITE(6r912) ( R A D ( I ) r I = l r N W ) W R I T E ( 6 8 9 1 3( )N C C ( I ) r I = l r N A L ) W R I T E ( 6 8 9 2 5()B ( I ) r I = l r N A L ) W R I T E (68927) (SCBR( I) I 1 " l 8 4 ) D O 1 7 0I = I / N W X(I) = X(I)/XINCH Y