Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Chapter 6, Problem 25P
To determine
The percentage reductions in space mean speed at the vicinity of the work zone, if the flow upstream is
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Traffic flow on a four-lane (one direction) freeway can be described by the Greenshields model. Two lanes of the four lanes on a section of this freeway will have to be closed to undertake an emergency bridge repair that is expected to take 2 hr. The mean free speed of the highway is 60 mi/h and the jam density is 140 veh/mi/ln. If it is estimated that the demand flow on the highway during the emergency repairs is 80% of the capacity, using the deterministic approach, determine: (a) The maximum queue length that will be formed (b) The total delay(c) The number of vehicles that will be affected by the incident(d) The average individual delay
Using 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:
What would be the capacity of the highway if the jam density 200 veh/km, and having a flow rate of 500 veh/hr whebn density is 155 veh/km?
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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- If the mean free speed and jam density for a highway were 60 mph and 160 vehicles per mile respectively, what would be the expected volume if the space mean speed of the traffic was 45 mph? At what other speed might this volume occurs?arrow_forwardA freeway with two northbound lanes is shut down because of an accident. At the time of theaccident, the traffic flow rate is 1200 vehicles per hour per lane and the flow remains at this level.The capacity of the freeway is 2200 vehicles per hour per lane when not impacted by an accident.The freeway is shut down completely for 20 minutes after the accident and then one lane is openfor 20 minutes and finally both lanes are opened (40 minutes after the accident). What is theaverage delay per vehicle resulting from the accident (assuming D/D/1 queuing)?arrow_forwarddue to closure of certain lanes of a highway, the capacity is reduced to 75% of its normal capacity. If in normal capacity the jam density of the highway is 103 veh/km, and the free flow speed is 58 kph, determine what would be the maximum flow if the flow is limited to 85% of its current state.arrow_forward
- Three routes connect an origin-destination pair with performance functions:t₁ = 20 +0.5x1t2 = 4+ 2x2t3=3+0.2x3with t in minutes and x in thousand vehicles per hour.(a) Determine the User Equilibrium flow on each route if q = 4000veh/h. (b) What is the minimum q (origin-destination demand) to ensure that all the three routes are used under user equilibrium? (c) Suppose that Route 1 is closed for repair. Find the system optimal flow on routes 2 and 3 and compute the total travel times.arrow_forwardWhat would be the capacity of the highway if the jam density 200 veh/km, and having a flow rate of 500 veh/hr when density is 155 veh/kmarrow_forwardPlease show me the process and steps. A) Traffic on a highway is said to follow the Greenshields model with jam density of 196 pc/mi/ln. The measured capacity is 3250 pc/h/ln. What is the free flow speed?arrow_forward
- Given a freeway flow study at a certain highway. The speed- density relationship is described in thegiven equation or relationship:V s = 60- 0.48kDetermine the following:a. Free-flow speed and jam densityb. Derive the equation describing flow and speed.c. Derive the equation describing flow and density.d. Determine the capacity of highwayarrow_forwardA traffic engineer has set up a one-mile study segment of a corridor. He measures the speed of 10 vehicles. Calculate the space mean speed and time mean speed of these vehicles. If the space mean speed occurs at an optimal flow with a density of 75 veh/mi, what is the capacity of this roadway?arrow_forwardA two-lane, one-way, rural freeway segment is being designed to service a demand volume of 4,000 vehicles per hour. The PHF is expected to be 0.95. If the combination of trucks, buses, and recreational vehicles is represented by a heavy vehicle adjustment of 0.85, what is the flow rate (pcphpl)? Provide your answer to the nearest integer.arrow_forward
- A stretch of four-lane, two-way highway 5.0 km long has a traffic volume of 35,000 vehicles per day. If for the last three years, the total number of accidents recorded was 1,900, determine the accident rate per 100 marrow_forwardTwo routes connect an origin and a destination and the flow is 15000 veh/h. Route 1 has a performance function t1=4+3*x1, and route 2 has a function of t2=b+6*x2, with the x's expressed in thousands of vehicles per hour and the t's in minutes. (a) If the user equilibrium flow on route 1 is 9780 veh/h, determine the free-flow speed on route 2(i.e. b) and equilibrium travel times. (b) If population declines reduce the number of travelers at the origin and the total origin-destination flow is reduced to 7000 veh/h, determine user equilibrium travel times and flows.arrow_forwardA one-way road is found to have a capacity of 2000 veh/hr. If a traffic enforcer says thatt thetraffic volume there is only 150 veh/hr, can you conclude that the traffic condition is not congested? Why or why not? Illustrate using a diagram.arrow_forward
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