Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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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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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
15
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?
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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- 6-5 The data shown below were obtained on a highway. Use regression analysis to fit these data to the Greenshields model and determine (a) the mean free speed, (b) the jam density, (c) the capacity, and (d) 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 55.0 15arrow_forwardProblem 6 Traffic on a single-lane urban street observes the following flow-density relationship: q=30k(1-k/180), where q is the traffic flow in vehicles per hour (VPH), and k is the traffic density in vehicles per mile (VPM). Answer the following questions: a. | Calculate the free flow speed, capacity, and jam density of the traffic flow. b. What is the minimum spacing and the minimum (time) headway of the traffic flow? What is the traffic volume when the travel speed is 20 MPH? C.arrow_forwardFor the following speed-density relationship of a highway, determine 1) mean free-flow speed, 2) jam density, and 3) capacity from the given data shown in table. The regression model is following Eq.1. Also, assess when this model could be used? U = U; * e kj) Eq.1 K (vpm) U (mph) 43 38.4 50 33.8 8 53.2 31 42.3arrow_forward
- 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?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_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 following. Speed (mi/h) Density (veh/mi) 16.7 84 25.7 69 35.2 54 43.1 40 54.4 19 56.1 14 (a) the mean free speed (in mi/h) mi/h (b) the jam density (in veh/mi) veh/mi (c) the capacity (in veh/h) veh/h (d) the speed at maximum flow (in mi/h) mi/harrow_forward
- .) A study of freeway flow at a particular site has resulted in a calibrated speed- density relationship as follows: V=57.5 (1-0.008 D); From this relationship, Find the free flow speed and the Jam density. Derive equations describing flow versus speed and flow versus density.arrow_forwardSpeed 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?arrow_forwardGiven Length of segment highway = 0.3 miles AADT = 1600 vehicles / day Test factor = 1.96 for 95% confidence level For a 4 year period: Average crash rate per million entering vehicles. Property damage = 250 Fatal (Death) = 120 Calculate the critical crash rate. 730 crashes O 973 crashes O 937 crashes O 708 crahsedarrow_forward
- 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 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_forwardThe number of crashes involving trucks (“truck crashes”) has continuously increased as thenumber of truck increases. To analyze the association of truck crash rates with the number oflanes, truck crash rates were compared between two-lane and multi-lane highways as shown inthe table below. Is the standard deviation of truck crash rates significantly higher for two-lanehighways than multi-lane highways?Note: Final answer should be either “The standard deviation of truck crash rates is significantlyhigher for two-lane than multi-lane highways” or “The standard deviation of truck crash rates isnot significantly higher for two-lane than multi-lane highways”.Truck crash rates (crashes/million vehicle-km)Site No. Two-lane highways Multi-lane highways12345670.2560.3420.8421.0210.3610.2620.8610.1880.3120.4210.2850.2250.183arrow_forwardQ1 (a) i. 10,000 vehicle speed traffic data were collected during the weekday on route FT050 at Batu Pahat, Johor. Suggest how to quantify and describe the basic characteristic of this data. Then explain how the method you suggested can help others to understand the data. (4 marks) ii. Consider the following data from 11 truck speed data climbing a hilly road. Compute 5 (FIVE) basic statistics of the sample speed as following: Sample mean Median а. b. с. Variance d. Range Standard error of the mean е. Speed (km/h) 25 Truck 1 2 35 3 55 4 15 40 6. 25 7 55 8. 35 9. 45 10 11 20arrow_forward
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