TTE%204004%20Chapter%202%2C8%20Continued

TTE%204004%20Chapter%202%2C8%20Continued - 1 • Actuated...

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Unformatted text preview: 1 • Actuated Signals and Detection –Concept: Capacity should change to meet demand –Basic Types of Controllers: •Semi-Actuated •Full-Actuated •Volume-Density 2 • Detection: Point (6X6 feet)-counter Area (Long induction loop) • Wide Area Video Detection • Control Features and Operation –Minimum Green Time: initial green interval+unit extension –Passage Time: comparable to unit extension. Also define Maximum Gap. 3 • Maximum Green Time: Terminates when there is a “call” on another phase • Recall Switch: For each phase. “On” means green comes back after phase terminates, “Off” means green rests at the last phase • Change Interval (Amber), and Clearance Interval (All Red) 4 Total Green Period Minimum Green Period Extension Period Maximum Period Time Actuation on a conflicting phase 5 • Timing Parameters: • Minimum green time: • G min = 4 + [2*Integer(d/20)] • G min = initial interval in seconds • d = distance between detector and stop line • 4 = start up time • 2 = saturation headway 6 • Passage Time: • P = d/(1.468*S) • P = Passage Time in seconds • d = distance from detector to stop line in feet • S = approach speed , mph • Maximum Green Time: determine optimal cycle length 7 Approach Speed Detector Set-Back Minimum Green Passage Time 15 40 8.0 3.0 20 60 10.0 3.0 25 80 12.0 3.0 30 100 14.0 3.5 35 135 18.0 3.5 40 170 22.0 3.5 45+ 72+ Volume-density or multiple detectors 8 d d N B A 25 80 30 8 1650 2 10 1700 5 20 55 18 40 mph 5 mph PHF=0.90 Detector Placement <30 feet 9 • Example 1: • For 25 mph speed, recommended detector set back = 80 feet > 30 • G min =4+[2*integer(30/20)]= 8 sec....
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This note was uploaded on 01/13/2011 for the course CECS Transporta taught by Professor Essamradwan during the Spring '10 term at University of Central Florida.

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TTE%204004%20Chapter%202%2C8%20Continued - 1 • Actuated...

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