Multi-objective Signal Simulation Optimization For Urban Oversaturated Arterial

The urban traffic congestion problems become increasingly prominent,it has become norm that the arterial keep oversaturated in case of the peak.Signal timing control thoroughfare of vehicles directly at intersections,thereby affecting the efficiency of arterial.How to optimize the oversaturated arterial signal timing schemes must be studied.To resolve signal timing optimization problem of urban oversaturated arterial,a method that combined with microscopic traffic simulation was implemented for multi-objective and multi-variable optimization by comparing the differences and applicable conditions of the existing methods.The main work is as follows :(1)According to analyzing the characteristics of grid map,the automation extraction and construction of arterial network was accomplished by using the image processing method.Car following and lane-changing model was studied by combining with the traffic characteristics of urban car.Then a microscopic simulation environment was constructed independently for evaluating the signal scheme;(2)The fast nondominated sorting genetic algorithm(NSGAII)was selected to implement multi-objective optimization.Based on the study of effect of repeated individuals on the algorithm results,the pre-selection strategy and a fast repetition detection method was proposed to eliminate the repeated individuals for improving the algorithm performance;(3)Based on the related theories of traffic signal control,the influence of different target and optimized parameters on traffic efficiency was analyzed under saturated condition,and then a traffic signal simulation optimization model was putted forward,this model took green split,phase sequence,offset and cycle as optimized parameters,meanwhile,vehicle average delay,system average queue-lane length ratio and system capacity were selected as optimized goals,combined with the simulation environment and optimization algorithm to optimize the signal timing scheme of all intersections of arterial.The collected traffic data from arterial consisted of three intersections was used to verify the model.The experimental results show that under the oversaturated state,the signal optimization method proposed by this thesis not only effectively control the vehicle queue length and balance the vehicle distribution,but also has better performance on the system capacity and average delay.