Research On Signal Timing Optimization Based On Left-turn Modes Of Non-motor Vehicles

Compared with western developed countries,the proportion of non-motor vehicles in the urban road traffic system in China is larger,and non-motor vehicles often do not abide by traffic rules in traffic activities,resulting in traffic disorder and frequent accidents,especially at intersections.The traditional intersection signal timing scheme only considers the motor vehicles at each entrance of the intersection for planning,with the goal of minimizing the average delay of motor vehicles but does not involve non-motor vehicles.However,at intersections,there is a great conflict between the non-motor vehicle flow and the motor vehicle flow,especially the conflict caused by the left-turn non-motor vehicle flow,which not only affects the traffic efficiency of the intersection,but also threatens the traffic safety of the intersection.Taking the left-turn non-motorized vehicle flow as the main research object,this paper carries on the signal phase combination and phase sequence optimization of the intersections under different left-turn modes,and obtains the optimal phase sequence scheme in each mode.On this basis,considering the operating benefits of motor vehicles,non-motor vehicles and pedestrians at the same time,and aiming at per capita delay,per capita conflict,and the average number of stops of motor vehicles,the signal timing of intersections is optimized.And the applicability of non-motor leftturn mode and the optimal signal control scheme at intersections were analyzed.Firstly,the characteristics of different street crossing modes and related traffic channelization setting methods of left-turn non-motor vehicles at signalized intersections are analyzed.Through field investigation and consulting literature,the traffic organization forms,advantages and disadvantages,traffic conflicts,green light interval,and the channelization of intersections in different crossing modes of non-motor vehicles at intersections are analyzed.Secondly,based on the analysis of the influence factors and design principles of phase sequence design under the condition of mixed traffic flow at signalized intersections,the phase sequence design process considering different left-turn modes of non-motor vehicles is discussed.At the same time,according to the difference of traffic flow demand in the same phase and the difference of switching time between phases,the phase combination optimization model based on multi-step clustering and the phase sequence optimization model based on the least loss time are established,respectively.Then,taking the per capita delay,per capita conflict,and the average number of stops at intersections as optimization objectives,a multi-objective timing optimization model based on left-turn modes of non-motor vehicles is designed.The model is transformed into a single objective function through the fuzzy preference thought,and then solved by the improved genetic algorithm.Finally,an intersection in Chengdu is selected for signal timing optimization analysis.After the basic data of intersections are obtained through field traffic investigation,the phase sequence optimization model and signal timing optimization model are solved,to analyze the applicability of left-turn modes of non-motor vehicles and optimal signal control scheme at intersections under the current conditions.The result of example analysis shows that the signal timing optimization model in this paper can significantly improve the operational quality of the intersection,reducing per capita delay by 28.1%,and reducing per capita conflict by 20.2%,which improves the traffic efficiency and traffic safety of the intersection.In addition,the nonmotor vehicle once crossing mode is more suitable for intersections with a large left-turn flow,but there is an upper limit of saturation constraint.