Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Question
Chapter 6, Problem 7P
To determine
(a)
Using regression analysis to fit these data to the Greenshields model and find the mean free speed.
To determine
(b)
Using regression analysis to fit these data to the Greenshields model and find the jam density.
To determine
(c)
Using regression analysis to fit these data to the Greenshields model and find the capacity.
To determine
(d)
Using regression analysis to fit these data to the Greenshields model and find the speed at maximum flow.
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Use linear regression to fit the highway speed/density data shown here to the Greenshields model, and use it to determine:
a. The mean free flow speed
b. The jam density
The capacity
The speed at max flow
R² of this data
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?
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 6 Solutions
Traffic and Highway Engineering
Ch. 6 - Prob. 1PCh. 6 - Prob. 2PCh. 6 - Prob. 3PCh. 6 - Prob. 4PCh. 6 - Prob. 5PCh. 6 - Prob. 6PCh. 6 - Prob. 7PCh. 6 - Prob. 8PCh. 6 - Prob. 9PCh. 6 - Prob. 10P
Ch. 6 - Prob. 11PCh. 6 - Prob. 12PCh. 6 - Prob. 13PCh. 6 - Prob. 14PCh. 6 - Prob. 15PCh. 6 - Prob. 16PCh. 6 - Prob. 17PCh. 6 - Prob. 18PCh. 6 - Prob. 19PCh. 6 - Prob. 20PCh. 6 - Prob. 21PCh. 6 - Prob. 22PCh. 6 - Prob. 23PCh. 6 - Prob. 24PCh. 6 - Prob. 25PCh. 6 - The arrival times of vehicles at the ticket gate...Ch. 6 - Prob. 27P
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, civil-engineering and related others by exploring similar questions and additional content below.Similar questions
- The 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 six vehicles on a 200 metre long section of road. Traffic data collected at the same time indicated an average time headway of 4 sec. Determine (a) the density on the highway, (b) the flow on the road, and (c) the space mean speed.arrow_forwardengineer 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_forward
- Data obtained from aerial photography showed nine vehicles on a 720 ft-long section of road. Traffic data collected at the same time indicated an average time headway of 4.2 sec. Determine the following. (a) the density on the highway (in veh/mi) veh/mi (b) the flow on the road (in veh/h) veh/h (c) the space mean speed (in mi/h) mi/harrow_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_forward1. Data on density and speed were obtained from a four-lane, two-way rural highway (in one direction only): Fitting the recorded data using linear regression, determine: a.the speed-density relationshipb.the correlation coefficientc.The capacity of the road.arrow_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 and the lowest rangearrow_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_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
- Consider only a single lane of a highway. Based on extensive data from an urban freeway it is assumed thatfree-flow speeds (i.e., there are no jams) can best be represented by a Normal distribution with mean andstandard deviation 119 km/h and 13.1 km/h, respectively.1. What is the probability that the speed of a randomly selected vehicle is between 100 and 120 km/h?2. What is the expected number of vehicles between two vehicles that exceed the posted speed limit of100 Km/h? You can use the Z table for calculating the final answer. You can also write your final answer in form ofR functions or as PDF/CDF of statistical distributions with correct arguments.arrow_forwardUsing Greenshields' model, for a highway with a mean free flow speed of 76 mi/h and jam density of 128 veh/mi, determine the density (in veh/mi) when the mean speed is observed to be 58 mi/h:arrow_forwardLinear regression analysis was performed on a set of traffic data using speed and density measurements from a highway segment. The following equation was developed. ?? = 57.5 − 0.457?? Use this equation, as well as the fundamental relationship equations to answer the following questions. What is the free-flow speed for this data? What is the jam density of this data? What is the maximum flow of this highway segment? What is the mean speed at this maximum flow?arrow_forward
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