Research On Signal Timing Method Of Left Turn Traffic Design And Optimization

In the urban road networks,intersection plays a very important role in gathering and dispersion of vehicles.At isolated intersections,a lot of conflicts can caused by left-turn traffic,it’s the main factor affecting the straight-through traffic flow.Therefore organization of the left-turn vehicles is significant for guidance of intersection’s traffic flow.At present,most of the planning,design timing scheme.Not only can it not effectively solve traffic jam of intersections,but also and management of intersections in China just use a fixed organization and signal generates some other traffic problems,such as low traffic capacity at intersections,increased vehicle exhaust emission.Based on the study of signal timing of left-turn traffic organization,this paper studies the design of a new type of left-turn traffic flow(continuous flow design),discusses organization and operation characteristics of left-turn traffic at continuous flow intersections.Besides,this paper also studies reasonable value of relevant parameters of continuous flow intersections,establishes a signal timing optimization scheme.The main work of this paper is as follows:Firstly,this paper introduces a new design method of left-turn traffic flow(continuous flow design).Based on queuing theory,the model of vehicle queue length is established.Then,the reasonable distance of primary and secondary intersections in continuous flow intersections is analyzed,queue length of vehicles,safety spacing,lane change and braking operations are taken into account.Secondly,traffic flow characteristics of continuous flow intersections and signal coordination control between the primary and secondary intersections are analyzed.Based on the different scenarios of the traffic flow,the analysis is carried out separately to establish a signal timing optimization model based on minimum delay of primary and secondary intersections.Thirdly,a typical intersection in Beijing is selected for case study.Based on geometric layout of current intersection,traffic data,spacing model of continuous flow primary and secondary intersection and signal timing optimization model proposed in this paper,continuous flow design scheme is carried out for the intersection.Then the traffic simulation software VISSIM is used to simulate operation of traffic flow,the simulation results of current situation and continuous flow scheme are analyzed.Finally,this paper summarizes research content and points out some inadequacies of the research.