Consider the problem of traffic flow on a three-lane (one direction) freeway which can be described by the Greenshields model. One lane of the three lanes on a section of this freeway will have to be closed to undertake an emergency bridge repair that is expected to take several hours. It is estimated that the capacity at the work zone will be reduced by 29 percent of that of the section just upstream of the work zone. The mean free flow speed of the highway is 65 mi/h and the jam density is 125 veh/mi/In. It is estimated that the demand flow on the highway during the emergency repairs is 86 percent of the capacity. Using the deterministic approach, determine the following for the expected repair periods of 1 h, 1.5 h, 2.5 h, 2.75 h, and 3 h. (a) the maximum queue length (in veh) that will be formed 1 h 1.5 h 2.5 h 2.75 h 3 h (b) the total delay (in h) veh veh veh veh veh 1 h h 1.5 h h 2.5 h h 2.75 h 3 h h h (c) the number of vehicles that will be affected by the incident 1 h 1.5 h 2.5 h 2.75 h 3 h veh veh veh veh veh (d) the average individual delay (in min) 1 h min 1.5 h min 2.5 h min 2.75 h min 3 h min (e) Plot a graph of average individual delay versus the repair period. Average Delay (h) Average Delay (h) 0.7 0.6 3 0.5 0.4 2 0.3 0.2 1 0.1 Repair Period (h) 1 2 3 4 Average Delay (h) 3 2 1 Repair Period (h) 0.2 0.4 0.6 Average Delay (h) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Repair Period (h) Repair Period (h) 0.2 0.4 0.6 1 2 3 4 (f) Use this graph to discuss the effect of the expected repair time on the average delay. The increase in expected repair time causes a decrease in average delay; the relationship is linear. ○ The increase in expected repair time causes an increase in average delay; the relationship is not linear. ○ The increase in expected repair time causes a decrease in average delay; the relationship is not linear. ○ The increase in expected repair time causes an increase in average delay; the relationship is linear.
Consider the problem of traffic flow on a three-lane (one direction) freeway which can be described by the Greenshields model. One lane of the three lanes on a section of this freeway will have to be closed to undertake an emergency bridge repair that is expected to take several hours. It is estimated that the capacity at the work zone will be reduced by 29 percent of that of the section just upstream of the work zone. The mean free flow speed of the highway is 65 mi/h and the jam density is 125 veh/mi/In. It is estimated that the demand flow on the highway during the emergency repairs is 86 percent of the capacity. Using the deterministic approach, determine the following for the expected repair periods of 1 h, 1.5 h, 2.5 h, 2.75 h, and 3 h. (a) the maximum queue length (in veh) that will be formed 1 h 1.5 h 2.5 h 2.75 h 3 h (b) the total delay (in h) veh veh veh veh veh 1 h h 1.5 h h 2.5 h h 2.75 h 3 h h h (c) the number of vehicles that will be affected by the incident 1 h 1.5 h 2.5 h 2.75 h 3 h veh veh veh veh veh (d) the average individual delay (in min) 1 h min 1.5 h min 2.5 h min 2.75 h min 3 h min (e) Plot a graph of average individual delay versus the repair period. Average Delay (h) Average Delay (h) 0.7 0.6 3 0.5 0.4 2 0.3 0.2 1 0.1 Repair Period (h) 1 2 3 4 Average Delay (h) 3 2 1 Repair Period (h) 0.2 0.4 0.6 Average Delay (h) 0.7 0.6 0.5 0.4 0.3 0.2 0.1 Repair Period (h) Repair Period (h) 0.2 0.4 0.6 1 2 3 4 (f) Use this graph to discuss the effect of the expected repair time on the average delay. The increase in expected repair time causes a decrease in average delay; the relationship is linear. ○ The increase in expected repair time causes an increase in average delay; the relationship is not linear. ○ The increase in expected repair time causes a decrease in average delay; the relationship is not linear. ○ The increase in expected repair time causes an increase in average delay; the relationship is linear.
Traffic and Highway Engineering
5th Edition
ISBN:9781305156241
Author:Garber, Nicholas J.
Publisher:Garber, Nicholas J.
Chapter6: Fundamental Principles Of Traffic Flow
Section: Chapter Questions
Problem 21P
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