Let's read COURSE HANDOUT HOW to DESIGN TRAFFIC LIGHT???
TERM OF TRAFFIC LIGHT CIRCULATION PHASE DESIGN Lost time : Time during which the intersection is not effectively utilized for any movement. Actual green time : It represents the time allocated for vehicles in that phase to proceed through the intersection without encountering a red signal. Effective green time : Green time plus the change interval minus the lost time for a designated phase Red time : A period during which all signal faces show red (for clearing off the vehicles in the intersection. Amber/ Yellow time : A time is provided after green time for movement. The purpose is to warn approaching driver during the end of a green time about the coming of a red signal. Cycle length : The time in seconds that it takes a signal to complete one full cycle of indications Interval : Indicates the change from one stage to another
02 03 05 The maximum capacity of vehicles that can pass through an intersection or a specific traffic lane during a given traffic signal cycle. It represents the highest number of vehicles that can move through the intersection under optimal conditions, assuming that all vehicles move smoothly and efficiently without any delays. Saturated Flow, S (pcu/hr) DESIGN PRINCIPLE Traffic Flow, q (pcu/hr) It refers to the movement of vehicles through an intersection or along a roadway, and it is a crucial factor considered when determining the timing and phasing of traffic signals. The Total Lost Time is an essential consideration in optimizing traffic signal timings to improve traffic flow and reduce delays at intersections. During the TLT period, no vehicles can progress through the intersection, and this time is considered unproductive as it doesn't contribute to the movement of traffic. Total Lost Time, L (s) It refers to the most efficient and effective duration of a complete signal cycle at an intersection. A signal cycle is the complete sequence of all traffic signal phases (green, yellow, and red) for all traffic movements at the intersection. It refers to the level of utilization or presence of vehicles and pedestrians within the intersection area. To determine the occupancy of the entire intersection, the lane occupancies from all approaches or lanes are combined. Y value (occupancy of the intersection) Optimum Cycle Time, Co (s)
STEP TAKEN IN DESIGN CALCULATE Y VALUE CALCULATE THE TOTAL LOST TIME CALCULATE THE CYCLE LENGTH OPTIMUM CALCULATE THE EFFECTIVE GREEN TIME CALCULATE THE ACTUAL GREEN TIME
TERM OF TRAFFIC LIGHT CIRCULATION PHASE DESIGN LET'S CREATE THE TIME PHASING GET DATA FROM PREVIOUS SOLUTION PUT THE ACTUAL GREEN TIME = 10 SEC AT PHASE 1 PUT THE INTERGREEN TIME = 4 SEC AFTER ACTUAL GREEN TIME PHASE 1 PUT THE ACTUAL GREEN TIME = 24 SEC AT PHASE 2 AFTER INTERGREEN PHASE 1&2 PUT THE INTERGREEN TIME = 4 SEC AFTER ACTUAL GREEN TIME PHASE 2