An Improved Green Ratio Model Based on Attemperment Priority in Oversaturated Traffic

The green ratio model of Webster ignores the difference of traffic flow in different traffic state. The paper introduces an idea of traffic priority. It deals out more green time for the phase which has the highest traffic demand in oversaturated traffic, so as to prevent and clear off the crowded traffic flow as soon as possible. Each phase gets the priority by turns, so the improved green ratio model can realize the goal of preventing traffic congestion and clearing off traffic blockage quickly. It is more effective than the Webster´s one in dealing with oversaturated traffic flow by simulating experiment based on VISSIM. And when vehicle arrival rate of each phase varies much, the improvement is obviously more.