Traffic And Highway Engineering
5th Edition
ISBN: 9781133605157
Author: Garber, Nicholas J., Hoel, Lester A.
Publisher: Cengage Learning,
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Chapter 6, Problem 24P
To determine
The resultant effect of a sudden reduction of the capacity on a highway due to a bottleneck using appropriate diagrams.
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The relationship between flow and density on a four-lane highway (two lanes per direction) is
known to follow GreenShiled's model, with a free flow speed of 100 km/h and a jam density of
80 veh/km/lane. One of the two lanes of the EB direction will be closed for an entire month for
maintenance. The traffic demand for the highway on a typical weekday is shown in the table below.
a) What is the maximum length of the queue upstream of the bottleneck during both the
morning and afternoon peak hours?
b) At what time will the morning and afternoon queues be dissipated?
c) Draw the shock wave diagram (for the entire day) showing shock wave speeds, critical
times, and distances.
Time
7:00 AM - 9:00 AM
9:00 AM 3:00 PM
3:00 PM 7:00 PM
7:00 PM–11:00 PM
11:00 PM 7:00 AM
Average Demand (vph)
3000
1500
3200
1200
400
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
Traffic flow on a three-lane (one direction) freeway 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 2 hours. It is estimated that the capacity at the work zone will be reduced by 25 percent of that of the section just upstream of the work zone. The mean free flow 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 85 percent of the capacity, using the deterministic approach, determine the following.
the maximum queue length (in veh) that will be formed
the total delay (in h)
the number of vehicles that will be affected by the incident
the average individual delay (in min)
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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- Traffic flow on a three-lane (one direction) freeway 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 2 hours. It is estimated that the capacity at the work zone will be reduced by 35 percent of that of the section just upstream of the work zone. The mean free flow speed of the highway is 50 mi/h and the jam density is 115 veh/mi/In. If it is estimated that the demand flow on the highway during the emergency repairs is 85 percent of the capacity, using the deterministic approach, determine the following. (a) the maximum queue length (in veh) that will be formed Your response differs from the correct answer by more than 10%. Double check your calculations. veh (b) the total delay (in h) h (c) the number of vehicles that will be affected by the incident veh (d) the average individual delay (in min) minarrow_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_forwardThe average daily traffic on a stretch of road is 300 commercial vehicles per lane per day. Design traffic repetitions for 10 years when vehicle damage factor is 2.5 and traffic growth rate is 7% isarrow_forward
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- A 1.5-mile section of a two-lane road has an AADT of 10,000. In a three-year period, there have been 6 fatal accidents and 12 non-fatal accidents. The state allows 350 accidents per 100 mvm for three years, of which 100 are fatal. For which value of confidence level, this highway is considered safe? If the following countermeasures are implemented: widening the existing lane by 2 feet, and widening the existing shoulder by 2 feet paved, and widening the clear zone by 5 feet, what will be the number of accidents reduced if the AADT became 12,000?arrow_forwardTwo lanes of the four lanes on a highway section have to be closed to undertake an emergency bridge repair that is expected to take 120minutes hr. The highway's mean free speed is 90km/h, and the jam density is 140 veh/km/ln. If it is estimated that the demand flow on the highway during the emergency repairs is 80% of the capacity (max flow), using the deterministic approach, determine: 1. The maximum queue length that will be formed.2. The number of vehicles that will be affected by the incident.3. The average individual delay.arrow_forwardThe DDHV fora given highway project is 2200 veh/h and the design capacity is 1450 veh/h/ln. The calculated number of lanes in this case is aboutarrow_forward
- Traffic flow on a section of a 2 lane road can be described by the Greenshields model with a mean free speed of 80 kph and jam density of 95 veh/km/lane. At the time when a flow was 90% of the capacity of the road, a large dump truck loaded with heavy industrial machinery from an adjacent construction site joins the traffic stream and travels at a speed of 20kph for a length of 6.60 km along the upgrade before turning off onto a dump site. Due to the relatively high flow in the opposite direction, it is impossible for any car to pass the truck. Find how many vehicles will be in the platoon behind the truck by the time the truck leaves the road. Find also the shockwave speed created by the truck.arrow_forwardOne of the following choices is not among the aspects that ( AADT ) volumes are used for : * Development of freeway and major arterial streets system. Evaluation of economic feasibility of highway project. Highway improvement and maintanance. Measuring the present traffic flow.arrow_forwardA proposed improvement will widen a two-lane rural highway from 9-ft-wide (per lane) to 11-ft-wide (per lane) if the highway has an AADT of 2100 veh/day. If there are an average of 25 crashes per year on the segment proposed for improvement, and 67% of the crashes are of the type targeted by the improvement, estimate the expected number of crashes (per year) after the improvement is constructed.arrow_forward
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