Study On Setting Condition And Evaluation Method Of Displaced Left-turn Signal Control Intersection

With the development of urban traffic,the urban traffic congestion phenomenon has become increasingly serious.The congestion at the intersection is the main bottleneck of the urban road network,so how to make better use of resources of time and space plane intersection is one of the keys to solve the urban road network traffic congestion.the optimization of plane intersection of left turn traffic flow organization is the key point to improve intersection capacity and security.In order to optimize the organization of leftturn traffic flow,traffic management departments have implemented a series of organization methods of left-turn traffic,such as banning left-turn,increasing the number of left-turn lanes,and making a roundabout left-turn,but the traditional method of left turn traffic flow organization,implementation effect is not ideal,and domestic and foreign scholars proposed a new type of left-turn traffic flow organization-Displaced Left-turn Signal Control Intersection.The displaced left-turn signal control intersection is opened at a specific position upstream of the main entrance of the main intersection,and a special left-turn lane is set at the outmost side of the right-turn lane,and the left-turn traffic is guided to the shift left turn lane through the sign and marking line,thus with straight traffic at the same time get the right of way,DLT changed the traditional left traffic transportation organization,so as to reduce the main intersection control phase and the conflict.However,the research on DLT is mainly based on foreign scholars,and there are few domestic studies.Therefore,this paper mainly focuses on the setting conditions and setting methods of shifting leftturn signal control,and through reasonable organization and signal control to achieve better traffic efficiency,and propose a comprehensive evaluation method for DLT to provide a scientific decision-making basis for traffic managers.Firstly,the basic concept and traffic operation mode of DLT are expounded,and the applicability condition of shift left turn signal control is summarized,including the feasibility condition and flow constraint condition,and then the lane number of DLT,the length of shift left turn dedicated lane and the design of auxiliary facilities are studied.Secondly,constructing the shifting left-turn vehicle queue length constraint model,and detailed analysis traffic capacity and the average vehicle delay of DLT based on traffic flow,and building the maximize capacity and the minimize average vehicle delay double target of DLT signal control timing model is used to solve the model based on NGSA-II algorithm.The DLT evaluation system is established,and the entropy weight method and the improved matter element extension method are combined to be used as DLT evaluation method.Finally,taking an intersection in chongqing as the case study object,the north and south entrances are set with the DLT,and the traffic operation of the intersection is studied and analyzed through the traffic simulation software.The results show that the setting of DLT can greatly improve the intersection capacity,reduce the average delay of the vehicle,and the traffic flow is smoother.DLT can be promoted and applied in China.