Research On Traffic Signal Control Methods Of Network Equilibrium Under Overstaturated State

The wide range of traffic congestion is frequently spread by the blocking of oversaturated intersection, and its distinguishing feature is that the traffic demand is greater than the traffic supply, then the vehicles cumulated. With the super saturation sustained, if the stranded vehicles cannot be reasonably redistributed, it will reach the upstream intersection and cause large traffic jams or transportation network gridlock. Therefore, the key to ensure a pourable road network is to control the demand of oversaturated intersection by inducing the traffic flow reasonably.This paper aims at transportation network equilibrium, prevent the queue upstream, and then redesign the related traffic signals by seeking for the reasonable path. At first, the paper analyzes the oversaturated traffic flow characteristics, identifies the state of intersection to ascertain the evaluation index which impact the operational efficiency of the traffic signal. And then the calculation model of equivalent queue length based on traffic wave theory and traffic flow theory is build. Secondly, the paper analyses the transportation network equilibrium theory, explains how to choose the reasonable path, and uses LOGIT function to compute the selection probability of each element in transportation network, and it also lays a foundation to raising control method. Once more, the paper uses queue length to restraint, considering the storage of the patch, raising the control method of the signal for the transportation network equilibrium. It focus on the principles of how to search the reasonable path, computing the intersection correlation degree, and also the signal control of transportation network equilibrium. Finally, the paper make the evaluation of the control effect by using VISSIM, by means of imitation, it shows that the control method of the signal in transportation network equilibrium could effectively remit the imbalances which are caused by the super saturation in the whole transportation network.