The volume at a section of a two-lane highway is 1500 veh/h in each direction and the density is about 25 veh/mi. A large dump truck loaded with soil from an adjacent construction site joins the traffic stream and travels at a speed of 10 mi/h for a length of 2.5 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. Vehicles just behind the truck therefore have to travel at the speed of the truck which results in the formation of a platoon having a density of 100 veh/mi and a flow of 1000 veh/h. Determine how many vehicles will be in the platoon by the time the truck leaves the highway

The volume at a section of a two-lane highway is 1500 veh/h in each direction and the density is about 25 veh/mi. A large dump truck loaded with soil from an adjacent construction site joins the traffic stream and travels at a speed of 10 mi/h for a length of 2.5 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. Vehicles just behind the truck therefore have to travel at the speed of the truck which results in the formation of a platoon having a density of 100 veh/mi and a flow of 1000 veh/h. Determine how many vehicles will be in the platoon by the time the truck leaves the highway

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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The volume at a section of a two-lane highway is 1500 veh/h in each direction and the density is about 25 veh/mi. A large dump truck loaded with soil from an adjacent construction site joins the traffic stream and travels at a speed of 10 mi/h for a length of 2.5 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. Vehicles just behind the truck therefore have to travel at the speed of the truck which results in the formation of a platoon having a density of 100 veh/mi and a flow of 1000 veh/h. Determine how many vehicles will be in the platoon by the time the truck leaves the highway. Draw the figure.
From an aerial photograph, one observes that on a level section of a (multilane) highway, 25% of the vehicles are trucks, 75% are cars, and there are 50 vehicles per mile of highway. The trucks travel at 40 mph and the cars at 60 mph. This highway also has a section with a steep grade on which the speed of the trucks drops to 25 mph and the speed of the cars to 55 mph. No vehicles enter or exit the subject highway sections (except at the ends). The flows on these highway sections are stationary, which means that the flows on the level section are equal to those on the grade. Determine (a) the flow of vehicles on the level section; (b) the density of vehicles on the grade; (c) the percent of trucks on the grade as seen from an aerial photo; (d) the percent of trucks as seen by a stationary observer on the grade.
What 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/km
A six-lane freeway (three lanes in each direction) in rolling terrain has 10-ft lanes and obstructions (fLW = 6.0 mph) 4 ft from the right edge of the traveled pavement (fLC = 0.8 mph). There are five ramps within three miles upstream of the segment midpoint and four ramps within three miles downstream of the segment midpoint. A directional peak-hour volume of 2000 vehicles (primarily commuters) is observed, with 600 vehicles arriving in the highest 15-min flow rate period. The traffic stream contains 12% large trucks (ET = 2.5) and buses and 6% recreational vehicles (ER = 2.0). What is the estimated free-flow speed of the traffic stream in mph (whole number, nearest 5)? Blank 1 What is the peak-hour factor (3 decimal places)? Blank 2 What is the heavy-vehicle adjustment factor (2 decimal places)? Blank 3 What is the service flow rate (whole number, nearest 5)? Blank 4 What is the service measure value if the average speed of the traffic stream is 65 mph (one decimal place)? Blank 5
A six-lane freeway (three lanes in each direction) in rolling terrain has 10-ft lanes and obstructions (fLW = 6.0 mph) 4 ft from the right edge of the traveled pavement (fLC = 0.8 mph). There are five ramps within three miles upstream of the segment midpoint and four ramps within three miles downstream of the segment midpoint. A directional peak-hour volume of 2000 vehicles (primarily commuters) is observed, with 600 vehicles arriving in the highest 15-min flow rate period. The traffic stream contains 12% large trucks (ET = 2.5) and buses and 6% recreational vehicles (ER = 2.0). What is the estimated free-flow speed of the traffic stream in mph (whole number, nearest 5)? What is the peak-hour factor (3 decimal places)? What is the heavy-vehicle adjustment factor (2 decimal places)? What is the service flow rate (whole number, nearest 5)? What is the service measure value if the average speed of the traffic stream is 65 mph (one decimal place)?
A six-lane freeway (three lanes in each direction) in rolling terrain has 10-ft lanes and obstructions (fLw = 6.0 mph) 4 ft from the right edge of the traveled pavement (fic = 0.8 mph). There are five ramps within three miles upstream of the segment midpoint and four ramps within three miles downstream of the segment midpoint. A directional peak-hour volume of 2000 vehicles (primarily commuters) is observed, with 600 vehicles arriving in the highest 15-min flow rate period. The traffic stream contains 12% large trucks (ET = 2.5) and buses and 6% recreational vehicles (ER = 2.0). 1.) What is the estimated free-flow speed of the traffic stream in mph (whole number, nearest 5)? 2.) What is the peak-hour factor 3.) What is the heavy-vehicle adjustment factor? 4.) What is the service flow rate? 5.) What is the service measure value if the average speed of the traffic stream is 65 mph
A highway section has an average spacing of 7.62m under jam conditions and a free-flow speed of 88km/hr. Assuming that the relationship between speed and density is linear, determine the jam density, the maximum flow, the density at maximum flow, and the speed at maximum flow.
The free-flow speed at section of an expressway is 85 mph and density at flow = 0 is 120 vehicle/mile. Determine the density when the flow is at maximum. Determine the maximum capacity. Determine the speed at maximum flow.
A four-lane freeway (two lanes in each direction) is located on rolling terrain and has 12-ft lanes, no lateral obstructions within 6 ft of the pavement edges, and there are two ramps within three miles upstream of the segment midpoint and three ramps within three miles downstream of the segment midpoint. The traffic stream consists of cars, buses, and large trucks (no recreational vehicles). A weekday directional peak-hour volume of 1800 vehicles (familiar users) is observed, with 700 arriving in the most congested 15-min period. If a level of service no worse than C is desired, b.) Determine the adjustment factor (Express in three decimals)
A four-lane freeway (two lanes in each direction) is located on rolling terrain and has 12-ft lanes, no lateral obstructions within 6 ft of the pavement edges, and there are two ramps within three miles upstream of the segment midpoint and three ramps within three miles downstream of the segment midpoint. The traffic stream consists of cars, buses, and large trucks (no recreational vehicles). A weekday directional peak-hour volume of 1800 vehicles (familiar users) is observed, with 700 arriving in the most congested 15-min period. If a level of service no worse than C is desired, c.) Determine the maximum number of large trucks and buses that can be present in the peak-hour Traffic stream. (Round off to nearest integer)
A four-lane freeway (two lanes in each direction) is located on rolling terrain and has 12-ft lanes, no lateral obstructions within 6 ft of the pavement edges, and there are two ramps within three miles upstream of the segment midpoint and three ramps within three miles downstream of the segment midpoint. The traffic stream consists of cars, buses, and large trucks (no recreational vehicles). A weekday directional peak-hour volume of 1800 vehicles (familiar users) is observed, with 700 arriving in the most congested 15-min period. If a level of service no worse than C is desired, a.) Determine the Freeflow Speed
A four-lane freeway (two lanes in each direction) is located on rolling terrain and has 12-ft lanes, no lateral obstructions within 6 ft of the pavement edges, and there are two ramps within three miles upstream of the segment midpoint and three ramps within three miles downstream of the segment midpoint. The traffic stream consists of cars, buses, and large trucks (no recreational vehicles). A weekday directional peak-hour volume of 1800 vehicles (familiar users) is observed, with 700 arriving in the most congested 15-min period. If a level of service no worse than C is desired, determine the maximum number of large trucks and buses that can be prersent in the peak hour traffic stream