CHAPTER 20 - BASIC PRINCIPLES OF INTERSECTION SIGNALIZATION

CHAPTER 20 - BASIC PRINCIPLES OF INTERSECTION...

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Unformatted text preview: Chapter 20 Chapter 20 Basic Principles of Intersection Signalization Basic Definitions 1. Cycle 2. Cycle Length ( C ) 3. Interval Green Interval Change Interval Clearance Interval Red Interval 4. Phase Types of Signal Control 1. Pretimed Operation 2. Semi-Actuated Operation 3. Full-Actuated Operation Types of Signal Coordination Master Controllers Computer-Controlled Systems Adaptive Traffic Control Systems: SCOOT (Split Cycle Offset Optimization Technique) SCATS (Sydney Coordinated Adaptive Traffic System) RHODES (Real-Time Hierarchical Optimized Distributed Effective System) Application of Types of Signal Control: Type of Fixed Applicable Principal Operation Cycle? Conditions Benefits Pretimed YES Detection Temporary Isolated not available installation Pretimed YES Consistent Predictable operations; Coordinated demand; Lowest costs of Closely- operation and spaced maintenance. intersections. Application of Types of Signal Control: Type of Fixed Applicable Principal Operation Cycle? Conditions Benefits Semi-Actuated NO Light x-street Low-cost for Isolated traffic. flexibility Full Actuated NO Isolated Responsive to wide Isolated location. variation in demand. Coordinated YES Arterial with Lower arterial varying side- delay; lower system street demands. delay potential. Permitted Left Turns Protected Left Turns Compound Left Turns Protected Plus Permitted Permitted Plus Protected Left-Turn Options Four Basic Mechanisms: Four Basic Mechanisms: DISCHARGE FROM A STANDING QUEUE DISCHARGE FROM A STANDING QUEUE Start-Up Lost Time: Start-Up Lost Time: Clearance Lost Time: Clearance Lost Time: Total Lost Time Per Phase: Total Lost Time Per Phase: Basic Concepts Basic Concepts Saturation Headway: Saturation Headway: Saturation Flow Rate: Saturation Flow Rate: ) / ( ) / ( ) / ( ln) / / ( 600 , 3 ) / ( 2 1 2 1 phase s t phase s phase s e hg veh h s veh s h L i + = = = āˆ‘ Basic Relationships Time Required to Move ā€œNā€ Vehicles Through a Single Green Phase (T): Effective Green Time for Phase i (g i ): Capacity of an Intersection Lane: h N T + = 1 = C g s c i i i e G g e Y ar y Y t t Y G g i i i i i i L L i i i +- =- = + = + =- + = 1 2 2 1 Sample Problem C = 90 seconds G = 40 seconds Y = 4 seconds l 1 = 2 seconds/phase e = 2 seconds/phase h = 2.2 seconds/vehicle Find: Capacity of Movement Per Lane NOTE: l 2 =Y-e=4-2=2 secs Cycles Per Hour : h cycles N c / 40 90 600 , 3 = = Time Available for Use at Saturation Headway : Seconds in Hour: 3,600 Deduction for Red Time: (90-40-4) 40 = -1,840 Deduction for Lost Times: (2+2)40 = -160 Time Available (secs) = 1,600 Capacity Per Lane : h veh c / 727 2 . 2 1600 = = Alternative Approach : Find the Saturation Flow Rate: Find the Capacity of a Lane: Find the Effective Green Time: ln / / 636 , 1 2 . 2 3600 hg veh s = = s e G g . 40 . 2 . 2 . 40 1 = +- = +- = h veh C g s c / 727 90 40 636 , 1 = = = Four Basic Mechanisms:...
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This note was uploaded on 01/18/2011 for the course PROJECT MA PM 587 taught by Professor Lee during the Spring '10 term at Keller Graduate School of Management.

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CHAPTER 20 - BASIC PRINCIPLES OF INTERSECTION...

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