Combined Dynamic Route Guidance and Signal Timing Optimization for Urban Traffic Congestion Caused by Accidents

When traffic congestion caused by accidents occurs on urban roads, the current signal control scheme may face failure. It is necessary to establish an effective dynamic route guidance scheme and formulate a reasonable signal timing scheme to alleviate the impact of the accident on urban traffic. In this paper, traffic congestion is divided into three states and the traffic evacuation strategies are formulated, respectively. Then, on the basis of analyzing the internal mechanism and spatiotemporal variation of queuing at intersections, a two-stage model is proposed to optimize the signal timing parameters. In the first stage, the basic timing parameters of each intersection, such as signal cycle and green ratio, are obtained. In the second stage, the offset optimization model is constructed to minimize the total delay time of the coordinated phase of all detour routes in the control scope, considering the early dissipation of queuing vehicles at the entrance of the intersection. This model is solved with a particle swarm optimization algorithm and simulated to the actual road network with VISSIM. As the experimental results show, this control method can greatly reduce the average vehicle delay, stop times, queue length, and the number of vehicles passing.