Consider the geometric and traffic characteristics shown below. Approach (Width) North (56 ft) South (56 ft) East (68 ft) West (68 ft) Peak hour Approach Volumes: Left Turn 165 105 200 166 Through Movement 447 400 590 543 Right Turn 162 157 191 200 Conflicting Pedestrian Volumes 900 1,200 1,200 900 PHF 0.95 0.95 0.95 0.95 For the following saturation flows: Through lanes: 1,600 veh/h/ln Through-right lanes: 1,400 veh/h/ln Left lanes: 1,000 veh/h/ln Left-through lanes: 1,200 veh/h/ln Left-through-right lanes: 1,100 veh/h/ln The total cycle length was 283 s. Now assume the saturation flow rates are 10% higher, that is, assume the following saturation flow rates: Through lanes: 1,760 veh/h/ln Through-right lanes: 1,540 veh/h/ln Left lanes: 1,100 veh/h/ln Left-through lanes: 1,320 veh/h/ln Left-through-right lanes: 1,210 veh/h/ln Determine a suitable signal phasing system and phase lengths (in s) for the intersection using the Webster method. (Enter the sum of green and yellow times for each phase, and afterwards the total cycle length. Ensure that enough green time is provided to allow for pedestrian movement. Assume each of the four approaches is divided into a left lane, a through lane, and a through-right lane. Assume the lost time due to acceleration and deceleration during each phase is 3.5 seconds, and the time lost due to the red clearance interval between each phase is 1.5 seconds. Also, assume the curb-to-curb distance is 56 ft when pedestrians travel during the N-S phases and 68 ft when pedestrians travel during the E-W phases. Finally, assume pedestrians walk at a speed of 3.5 ft/s through a crosswalk of width 10 ft.) Phase 1: N-S left turn __________? Phase 2: N-S through & through-right turn _____________? Phase 3: E-W left turn___________? Phase 4: E-W through & through-right turn________? Total cycle length_______? What effect does the increase in saturation flow rates have on cycle length?

Consider the geometric and traffic characteristics shown below. Approach (Width) North (56 ft) South (56 ft) East (68 ft) West (68 ft) Peak hour Approach Volumes: Left Turn 165 105 200 166 Through Movement 447 400 590 543 Right Turn 162 157 191 200 Conflicting Pedestrian Volumes 900 1,200 1,200 900 PHF 0.95 0.95 0.95 0.95 For the following saturation flows: Through lanes: 1,600 veh/h/ln Through-right lanes: 1,400 veh/h/ln Left lanes: 1,000 veh/h/ln Left-through lanes: 1,200 veh/h/ln Left-through-right lanes: 1,100 veh/h/ln The total cycle length was 283 s. Now assume the saturation flow rates are 10% higher, that is, assume the following saturation flow rates: Through lanes: 1,760 veh/h/ln Through-right lanes: 1,540 veh/h/ln Left lanes: 1,100 veh/h/ln Left-through lanes: 1,320 veh/h/ln Left-through-right lanes: 1,210 veh/h/ln Determine a suitable signal phasing system and phase lengths (in s) for the intersection using the Webster method. (Enter the sum of green and yellow times for each phase, and afterwards the total cycle length. Ensure that enough green time is provided to allow for pedestrian movement. Assume each of the four approaches is divided into a left lane, a through lane, and a through-right lane. Assume the lost time due to acceleration and deceleration during each phase is 3.5 seconds, and the time lost due to the red clearance interval between each phase is 1.5 seconds. Also, assume the curb-to-curb distance is 56 ft when pedestrians travel during the N-S phases and 68 ft when pedestrians travel during the E-W phases. Finally, assume pedestrians walk at a speed of 3.5 ft/s through a crosswalk of width 10 ft.) Phase 1: N-S left turn ____? Phase 2: N-S through & through-right turn _? Phase 3: E-W left turn_? Phase 4: E-W through & through-right turn? Total cycle length___? What effect does the increase in saturation flow rates have on cycle length?

Traffic and Highway Engineering

5th Edition

ISBN:9781305156241

Author:Garber, Nicholas J.

Publisher:Garber, Nicholas J.

Chapter7: Intersection Design

Section: Chapter Questions

Problem 9P

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Question

Consider the geometric and traffic characteristics shown below.

Approach (Width)	North (56 ft)	South (56 ft)	East (68 ft)	West (68 ft)
Peak hour Approach Volumes:
Left Turn	165	105	200	166
Through Movement	447	400	590	543
Right Turn	162	157	191	200
Conflicting Pedestrian Volumes	900	1,200	1,200	900
PHF	0.95	0.95	0.95	0.95

For the following saturation flows:

Through lanes:

1,600 veh/h/ln

Through-right lanes:

1,400 veh/h/ln

Left lanes:

1,000 veh/h/ln

Left-through lanes:

1,200 veh/h/ln

Left-through-right lanes:

1,100 veh/h/ln

The total cycle length was 283 s. Now assume the saturation flow rates are 10% higher, that is, assume the following saturation flow rates:

Through lanes:

1,760 veh/h/ln

Through-right lanes:

1,540 veh/h/ln

Left lanes:

1,100 veh/h/ln

Left-through lanes:

1,320 veh/h/ln

Left-through-right lanes:

1,210 veh/h/ln

Determine a suitable signal phasing system and phase lengths (in s) for the intersection using the Webster method. (Enter the sum of green and yellow times for each phase, and afterwards the total cycle length. Ensure that enough green time is provided to allow for pedestrian movement. Assume each of the four approaches is divided into a left lane, a through lane, and a through-right lane. Assume the lost time due to acceleration and deceleration during each phase is 3.5 seconds, and the time lost due to the red clearance interval between each phase is 1.5 seconds. Also, assume the curb-to-curb distance is 56 ft when pedestrians travel during the N-S phases and 68 ft when pedestrians travel during the E-W phases. Finally, assume pedestrians walk at a speed of 3.5 ft/s through a crosswalk of width 10 ft.)

Phase 1: N-S left turn __________?
Phase 2: N-S through & through-right turn _____________?
Phase 3: E-W left turn___________?
Phase 4: E-W through & through-right turn________?
Total cycle length_______?

What effect does the increase in saturation flow rates have on cycle length?

By increasing saturation flow rates by 10%, the recommended total cycle length decreased by ___
Show a detailed layout of the phasing system and the intersection geometry used.

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