• Author / Uploaded
• Belal AL Qaisi

Citation preview

TRANSPORTATION ENGINEERING HOMEWORK # 1 SOLUTION Problem # 1

Downgrade S = 1.47(60)(2.5) + (60)2 / 30(0.35 – 0.04) S = 220.50 + 387.10 S = 607.60 feet Upgrade S = 1.47(60)(2.5) + (60)2 / 30(0.35 + 0.04) S = 220.50 + 307.70 S = 528.19 feet Use the downgrade (607.6 ft)

Problem 2

1

Problem 3

Problem 4

Problem 5

2

Problem 6 Speed data collected on an urban roadway yielded a standard deviation in speeds of ±4.8 mi/hr. (a) If an engineer wishes to estimate the average speed on the roadway at a 95% confidence level so that the estimate is within ±2 mi/hr of the true average, how many spot speeds should be collected? (b) If the estimate of the average must be within ±1 mi/hr, what should the sample size be? SOLUTON

3

Problem 7 An engineer wishing to obtain the speed characteristics on a bypass around her city at a confidence level of 95%, and an acceptable limit of ± 1.0 mi/hr collected a total of 130 spot speed samples and determined that the variance is 25 (mi/hr)2. Has the engineer met all of the requirements of the study?

SOLUTION

Problem 8 An engineer wishing to determine whether there is a statistically significant difference between the average speed of passenger cars and that of large trucks on a section of highway, collected the data shown below. Determine whether the engineer can conclude that the average speed of large trucks is the same as for passenger cars.

SOLUTION

4

Problem 9 A local jurisdiction has determined that for a given set of geometric conditions, a maximum rate of 8 crashes/million entering vehicles can be tolerated. At an intersection of two roadways with ADTs of 10,000 and 7500, how many crashes can occur before corrective action must be sought?

SOLUTION

5

Problem 10 Studies were conducted at two sites on rural roads with similar characteristics. The first site was 5.1 miles in length with an ADT of 6500. Over the year-long study period, 28 crashes occurred on this portion of roadway, five of them resulting in fatalities. The second site was a 10-mile section with an ADT of 5000. There were 32 crashes in this section with four fatalities. Determine the appropriate crash rates for both locations, and discuss the implications (i.e., which site is more dangerous?).

SOLUTION Site 1

Site 2

6