A SIMULATION MODEL FOR U-TURN TRAFFIC CAPACITY

Abstract One of the common traffic management techniques for left turns in Cairo urban intersections is replacing direct left-turns with U-turns; basically to eliminate direct left turn movements at the intersection. Currently there is a lack of models that estimate the capacity of U-turns at median openings. Congested U-turns make traffic traveling very slowly and create some opportunities for vendors which further slowing down the already congested vehicular traffic. The objective of this paper is to develop a simulation model to determine capacity of U-turns at uncontrolled mid-block median openings with no police control. The proposed model is based on the gap acceptance process. Results showed when the median width was comfortably sufficient; it leaded to a higher U-turn capacity. The U-turn movement at a wide median can reach a maximum capacity of about 985 veh/hr when there is no conflicting traffic. The capacity of U-turn decreases as the conflicting volume increases. The capacity is reduced to 540 veh/hr and 380 veh/hr when the conflicting volume is 1000 and 1500 veh/hr per lane.