Research On Vehicle Lane Changing Safety In The Downstream Area Of Toll Station Based On Trajectory Data And Dynamic Simulation

As the key node of the expressway,the toll station directly affects the overall service level,traffic safety and capacity.In the downstream area where the toll station connects with the urban road,the limited road space and the overlapping diversion decision of drivers will cause frequent vehicle speed changes and lane-changing.Its safety characteristics and traffic flow characteristics are significantly different from those of ordinary sections,which is very easy to lead to traffic flow disorder and increase the risk of accidents.The reliability and efficiency of vehicle lane changing trajectory have a close impact on traffic safety characteristics.Exploring the characteristics of dynamic parameters in the process of vehicle lane changing can accurately analyze the safety of lane changing process,so as to expand the research scope of lane changing safety.Based on the study of the traffic flow characteristics and traffic conflict distribution characteristics in the downstream area of the toll station,this paper focuses on the simulation research on the dynamic parameters of vehicles in the process of lane-changing and puts forward the corresponding safety control measures.Firstly,Huai’an toll station was taken as the research area,then a large amount of vehicle micro trajectory data was extracted from the video through the YSKT vehicle detection and tracking technology framework,and then mathematical statistics on the vehicle speed characteristics,lane changing characteristics,vehicle lane selection characteristics and vehicle driving time characteristics of different sections and vehicle types were made based on reasonable division of the research area,which revealed the difference of driving characteristics between ETC vehicles and MTC vehicles in the target area.Secondly,the traffic conflict technology was taken as the traffic safety evaluation method and two typical alternative indicators of traffic conflict ETTC and PET were selected to evaluate the potential traffic conflict risk in the downstream confluence area of the toll station,and the spatial distribution characteristics and severity characteristics of traffic conflict,as well as the impact of toll channel selection and termination lane selection on traffic conflict were analyzed.The results indicated that there existed significant differences in the distribution characteristics of traffic conflicts between ETC vehicles and MTC vehicles.At the same time,the choice of the different initial lane and termination lane would lead to different conflict distributions due to the different initial speed,spatial position and driving demand of vehicles.Thirdly,based on the research on the characteristics of traffic flow and the distribution of traffic conflicts,the kinetic parameters of vehicles in the process of lane-changing were studied.A framework based on quintic polynomial lane-changing trajectory planning and model predictive control algorithm(MPC)was constructed.The mathematical statistics results of the actual trajectory were input into Car Sim and Simulink joint simulation platform to simulate six typical working conditions of ETC vehicles and MTC vehicles in the downstream area to comprehensively compare the safety,comfort and handling stability of various kinetic parameters.Then a simulation model of the same scene of toll station in VISSIM was built to supplement and analyze the safety characteristics of traffic flow and lane-changing behavior.Finally,reasonable suggestions were made on the improvement of safety level based on the study of traffic flow characteristics,driving behavior characteristics,traffic conflict characteristics and vehicle lane changing dynamic parameters in the area.