Abstract
The saturation flow rate in peak hours is different from saturation flow rate in non- peak flow times. New factors regarding the effect of heavy vehicles have been ascertained. The traffic volume which can enter a traffic signal- controllers intersection depends on the rate of flow of vehicles passing the stop line during the green period and on the length of green time available with an investigation at signalized intersections of major highways in large cities the effect of different traffic flow by time of day on capacity (saturation flow rate) has been analyzed. The result shows that in peak traffic flow the time gap at the stop line for passenger cars is about 8% shorter than in the time between peak hours.