Traffic and Highway Engineering
5th Edition
ISBN: 9781305156241
Author: Garber, Nicholas J.
Publisher: Cengage Learning
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Chapter 6, Problem 21P
To determine
Number of vehicles that will be in the platoon behind the truck by the time the truck leaves the highway.
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Traffic flow on a section of a two-lane highway can be described by the Greenshields model, with a mean free speed of
54 mi/h and a jam density of 146 veh/mi/In. At the time when the flow was 90 percent of the capacity of the highway, a large
dump truck loaded with heavy Industrial machinery from an adjacent construction site joins the traffic stream and travels at a
speed of 18 mi/h for a length of 3.5 mi 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. Determine how many vehicles will be in the platoon
behind the truck by the time the truck leaves the highway.
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.
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)
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 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 delayarrow_forwardTraffic 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)arrow_forwardQuestion A linear relationship is observed between speed and density on a certain section of a highway. The free flow speed is observation to be 80 km per hour and the jam density is estimated as 100 vehicles per km length. Based on the above relationship, the maximum flow expected on this section and the speed at the maximum flow will respectively bearrow_forward
- The traffic demand for a six-lane urban arterial road (three lanes per direction) is given in the table below. The relationship between flow and density for this road follows GreenShiled's model, with a free flow speed of 105 km/h and a jam density of 92 veh/km/lane. Two of the three lanes of the EB direction were closed at 5:00 AM for maintenance. The two lanes were re-opened at 8:00 AM, allowing the traffic to be released at capacity conditions. a) What is the maximum length of the queue upstream of the bottleneck? b) At what time the queue upstream of the bottleneck will be fully dissipated? c) What is the furthest point upstream of the bottleneck that will be impacted by the lane closure? d) Draw the shock wave diagram showing shock wave speeds, critical times, and distances. Time 5:00 6:00 AM 6:00 7:00 AM 7:00 8:00 AM 8:00 9:00 AM 9:00 10:00 AM 10:00 11:00 AM Demand (vph) 2000 4000 6400 6000 3600 3000arrow_forwardThe 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 400arrow_forwardEx2/ The speed density relationship of traffic on a section of free way lane was Vs =18.2ln 220 1- what is the max flow, speed and density at this flow ? 2- what is the jam density ?arrow_forward
- A freeway is being designed for a location in mountainous terrain. The expected free-flow speed is 55 mi/h. Lane widths will be 12 ft and shoulder widths will be 6 ft. During the peak hour, it is expected there will be a directional peak-hour volume of 2700 vehicles, 12% large trucks and buses and 6% recreational vehicles. The PHF and driver population adjustment are expected to be 0.88 and 0.90, respectively. If a level of service no worse than D is desired, determine the necessary number of lanes.arrow_forward3.2 A roadway with only one lane in each direction carries traffic of 1200 veh/h at a point where there is a no passing solid line. The density is 20veh/h. A truck carrying a heavy load enters the traffic at 34km/h and this continues for a stretch of 5km before there is a passing lane and the truck can move over to the left hand lane. During this time the vehicle density increased to 80veh/km, decrasing the flow to 900veh/h. Calculate the length of the platoon and the number of vehicles involved.arrow_forwardA segment of rural freeway is being designed for a FFS of 70 mph through rolling terrain. The directional (i.e. one-way) design volume is 3,000 vehicles per hour. If 10% of the design volume is expected to be heavy vehicles (i.e. trucks and buses), what is the heavy vehicle adjustment used to determine the flow rate? Provide you answer to the nearest hundredths.arrow_forward
- 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 55 mi/h and the jam density is 130 veh/mi/ln. It is estimated that the demand flow on the highway during the emergency repairs is 84 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 (b) the total delay (in h) (c) the number of vehicles that will be affected by the incident (d) the average individual delay (in min)arrow_forwardConsider 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 28 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. 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 (b) the total delay (in h) (c) the number of vehicles that will be affected by the incident (d) the average individual delay (in min) (e) Plot a graph of average individual delay…arrow_forward..Average free flow speed and the jam density observed on a road stretch are 60 km/h and 120 vehicles/km, respectively. For a linear speed-density relationship, the maximum flow on the road stretch (in vehicles/h) is_arrow_forward
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