Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Question
Chapter 4, Problem 6P
To determine
The speed of the road, estimate of 85th percentile speed.
Expert Solution & Answer
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Students have asked these similar questions
For a spot speed study in which 100 observations were obtained, the mean speed was 52km/h and the standard deviation was 4.6 km/h.
1.What is the margin of error on the estimate of true mean speed obtained from this sample?
2.What is a reasonable estimate of the 85th percentile speed based on the information available?
Use N = ( )2 in your determinations. In addition read up on 85th percentile speed.
For a spot speed study in which 100 observations were obtained, the mean speed was 52 km/h and the standard deviation was 4.6 km/h. (BO0K: Traffic % Highway engineering, N. Gruber SI unit)
What is the margin of error on the estimate of true mean speed obtained from this sample?
What is a reasonable estimate of the 85th percentile speed based on the information available?
Speed data collected on an urban roadway yielded a standard deviation in speeds
of 4.8 mi/h.
(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/h of the true average, how
many spot speeds should be collected?
(b) If the estimate of the average must be within 1 mi/h, what should the sample
size be?
Chapter 4 Solutions
Traffic and Highway Engineering
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Similar questions
- engineer wishing to determine the travel time and average speed along a section of an urban highway as part annual trends analysis on traffic operations conducted a travel time study using the floating -car technique .He carried out 10 runs and obtained a standard deviation of +-3 mi/h in the speeds obtained .if 5% significance level is assumed is the number of test runs adequate?arrow_forwardAn engineer wishing to obtain the speed characteristics on a bypass around her city at a confidence level of 95%, and an acceptable limit of 2.0 km/h collected a total of 104 spot speed samples and determined that the variance is 4.8 km/h. Has the engineer met with all of the requirements of the study? 1.What is the variance in this question; 'the lambda'? 2.What is acceptable error in this question 3.What is the minimum number of observations to meet the requirements of the study 4. Has the engineer met with the requirements of the study? File a YES or NO responsearrow_forwardAn engineer, wishing to determine the travel time and average speed along a sectionof an urban highway as part of an annual trend analysis on traffic operations, conducteda travel time study using the floating-car technique. He carried out 10 runs andobtained a standard deviation of ±3 mi/h in the speeds obtained. If a 5% significancelevel is assumed, is the number of test runs adequate?arrow_forward
- An engineer, wishing to determine the travel time and average speed along a section of an urban highway as part of an annual trend analysis on traffic operations, conducted a travel time study using the floating-car technique. He carried out 10 runs and obtained a standard deviation of ±3.4 mi/hin the speeds obtained. If a 5 percent significance level is assumed, is the number of test runs adequate?arrow_forwardA spot speed study was conducted on a freeway on which the mean speed and standard deviation were found to be 72.4 km/h and 5.4 km/h, respectively. What is the range of values that would be expected to contain the middle 95% speeds 1 what is top and the lowest rangearrow_forwardThis is a three-part question. Data obtained from aerial photography showed eight vehicles on an 800 ft-long section of road. Traffic data collected at the same time indicated an average time headway of 3.7 sec. Part A. Determine the density on the highway in vehicles per mile. Part B. Determine the flow on the road in vehicles per hour. Part C. Determine the space mean speed in mph.arrow_forward
- The accompanying data show spot speeds collected at a section of highway located in a residential area. Using the student's t test, determine whether there was a statistically significant difference in the average speeds at the 95% confidence level.arrow_forwardThe data shown below were obtained by time-lapse photography on a highway. Use regression analysis to fit these data to the Greenshields model and determine The mean free speed The jam density The capacity The speed at maximum flow Speed(mi/h) Density (veh/mi) 14.2 85 24.1 70 30.3 55 40.1 41 50.6 20 55 15arrow_forwardData obtained from aerial photography showed 8 vehicles on a 356 m-long section of road. Traffic data collected at the same time indicated an average time headway of 4.8 sec. Determine the space mean speed in km/hr to one decimal place in accuracyarrow_forward
- A spot speed study was conducted on a freeway on which the mean speed and standard deviation were found to be 72.4 km/h and 5.4 km/h, respectively. What is the range of values that would be expected to contain the middle 95% speeds 1 what is top range 2. what is the lowest rangearrow_forwardTo measure the spot speed of vehicles on a certain accident-prone location along MacArthur Highway, a trap length equal to 40 m long was set. The times in seconds clocked by an observer for 24 vehicles were: (see table below). Determine the spot speed or time mean speed. If the maximum speed limit at the location was set at 60 kph, determine the percentage of drivers violating the regulation? (Note: This is just an illustrative problem; more data are actually needed for this kind of analysis.)arrow_forwardFor this question, you will be required to upload your approach and solution. Determine the AADT on a rural primary road for the following data: Time of day Volume 0600 - 0700 435 0700 - 0800 550 0800 - 0900 572 Data collected was on a Wednesday during the month of August.arrow_forward
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