Multi-objective Optimization Of Intersection Signal Timing In Urban Traffic Congestion Sections

With the rapid development of the economy,the demand for transportation is increasing.Nowadays,traffic congestion has become a serious problem in cities.Its direct impact is long delays and long queues of vehicles,which leads to the reduction of traffic operation efficiency.In addition,it will also lead to reduced transport performance,such as an increased indicators such as fuel consumption and air pollution.With sustainable development becoming the theme of contemporary world development,in recent years reducing energy consumption and tail gas emission has become a research hotspot.However,most of the existing signal timing models focus on the efficiency of traffic operation and rarely consider the benefits of the external environment.Therefore,it is of great theoretical and practical significance to make a meaningful trade-off between traffic efficiency and environmental benefits through the control and optimization of road traffic.This paper mainly studies the multi-objective optimization and adjustment strategy of signal timing at urban traffic congested sections of an intersection.The three objective functions to measure the time signal optimization of the intersection are the total vehicle delay of the intersection,the queue length and the CO emissions.A PSO-GA hybrid algorithm is proposed to solve the model,which introduces crossover and mutation operators of genetic algorithm(GA),and combines with the global optimal guidance capability of particle swarm optimization(PSO).The optimal solution can be obtained better and faster.Synchro traffic simulation software is combined with various schemes and algorithms to evaluate the advantages and disadvantages of different timing schemes(including existing schemes,Synchro optimization schemes,GA models and proposed PSO-GA models).The main research results of the thesis are as follows:(1)A multi-objective optimization model for signal timing of urban intersections under low carbon conditions is established,and the PSO-GA hybrid algorithm is used to solve the model.Two weight coefficients reflecting traffic efficiency and environmental benefit preferences are introduced to transform the multi-objective optimization problem into a single-objective minimization problem.The PSO-GA hybrid algorithm is used to solve multi-objective problems.The algorithm is based on the GA algorithm and the PSO algorithm,and combines the benefits of the two algorithms,which has the characteristics of fast convergence and good stability.Under the existing traffic conditions,the PSO-GA scheme can improve the traffic conditions and the external environment to the greatest extent.(2)Synchro simulation software is used to simulate and optimize the intersection.According to the intersection signal optimization function of Synchro system,the intersection timing and optimization are re-carried out to generate Synchro optimization scheme.At the same time,Synchro system is used to simulate different timing schemes of intersections.Based on the simulation results,the optimal scheme under the current traffic flow condition is obtained,and the advantages and disadvantages of different signal timing schemes are evaluated.(3)Taking an intersection in Wuhan as an example,multi-objective optimization of urban intersection timing under low-carbon conditions is carried out.Comparing the performance index values of GA algorithm and PSO-GA algorithm,it is found that the PSO-GA hybrid algorithm is an effective method to solve the signal timing problem.Nine different scenarios(indicating different traffic efficiency and environmental benefit preferences)under the PSO-GA model are evaluated using the Synchro system.Through the analysis,the optimal weight optimization strategy is obtained,and it is found that the emission level is determined by the environmental benefit and traffic efficiency comprehensively,and reducing the environmental benefit does not mean the improvement of traffic operation condition.By comparing the road optimization effects of various timing schemes,the PSO-GA optimal scheme proposed can achieve better signal optimization control and achieve higher traffic efficiency under low carbon conditions.