Research On Traffic Signal Timing Method Based On Bus Priority Strategy

With the continuous improvement of social and economic level and the rapid development of automobile industry,the number of automobiles is increasing,which also brings serious urban traffic congestion problems.In order to solve the problem of traffic congestion,the state has increased investment in road infrastructure,made reasonable planning for urban traffic,and vigorously developed urban viaducts,subways and other three-dimensional transportation,but due to the limited space resources of urban roads,road construction has been unable to meet the growing traffic demand.How to improve road efficiency and reduce road congestion without increasing road space has become a top priority for current research.Public transportation vehicles have the advantages of high passenger numbers and high transportation efficiency.Therefore,vigorous development of public transportation has become one of the main solutions to relieve road pressure at present,and the bus priority mechanism is supported by the government.However,with more and more buses on the road,the conflict of multiple buses requesting priority passage at the same time in active bus priority control becomes more and more inevitable,and passive priority control is more suitable for this situation.Therefore,this paper optimizes single-intersection bus priority timing parameters based on passive bus priority control and applies bus priority control to arterial coordination on this basis.The following research results are achieved in this paper:For single intersection bus priority signal control,this paper designs a two-layer optimization model and implementation method for intersection bus priority timing based on the bus priority control method with minimum per capita delay,considering the high impact of priority phases on non-priority phases when the intersection road saturation is high.The model takes the sum of intersection traffic flow rate ratio as the weight and the weighted minimum of per capita delay and vehicle delay as the objective,establishes the green ratio timing optimization model,and establishes the dual-objective optimization model to optimize the intersection cycle with the intersection per capita delay and traffic capacity as the optimization objective,and finally combines the two to get the intersection bus priority timing two-layer optimization model.The simulation validation uses the general-purpose VISSIM software,selects an intersection in Xi’an city as the simulation object,collects the traffic flow data in flat and peak hours respectively,writes an algorithm to solve the optimization model and obtains the parameters of the intersection bus priority timing scheme,and selects the per capita delay,average vehicle delay,maximum queue length and vehicle traffic volum as the evaluation indexes in the simulation to validate the timing scheme.The results show that the intersection bus priority timing two-tier optimization method proposed in this paper can effectively reduce the per capita delay and the average bus delay at intersections,and reduce the intersection vehicle queue length and improve the intersection traffic efficiency.Based on the study of bus priority timing at single intersections,this paper combines the theoretical knowledge of bus priority and arterial coordination to apply the bus priority control mechanism to arterial coordination.Based on the classical number solution method,a multi-objective optimization model is developed to optimize the arterial public cycle and offset with the arterial green wave bandwidth,per capita delay and traffic capacity as the optimization objectives.Suitable arterial coordination sections are selected,peak hour traffic flow data are collected,algorithms are written to solve to obtain the arterial bus priority coordination control scheme,VISSIM software is used to build the arterial coordination system control scheme for simulation and validation,and the control effect is evaluated using arterial travel time,average vehicle delay,number of stops and average queue length as evaluation indicators.The results show that the arterial bus priority coordination control approach proposed in this paper can more effectively reduce the travel time of arterial passage of bus vehicles and reduce the average delay and average queue length of vehicles,alleviate traffic congestion and improve the efficiency of arterial system passage.