Research On Signal Control Strategy Of Variable Approach Lane At The Intersection

With the continuous increasing of the number of motor vehicles,traffic congestion has become a major problem facing by the city.One of the keys to solve the problem of traffic congestion is to improve the efficiency of urban intersections.Whether the function of the road and the design of signal timing is reasonable will directly affect the running state of the whole urban traffic network.In order to solve the phenomenon that the traffic flow in the entrance of the intersection is unbalanced,variable approach lane arises spontaneously.It can adjust the lane function according to the traffic demand,so that to make full use of road resources at intersections.At the same time,with the change of the lane function,the signal timing should also be adjusted accordingly,in order to maximize the operating efficiency of the intersection.Firstly,this paper analyzes the road and signal timing conditions,defines the setting conditions of the variable approach lane at intersections,and briefly introduces its induction method and the calculation of empty time.According to the goal and principle of variable approach lane,this paper analyzes the control method and control logic of variable approach lane system.Secondly,based on the average delay of the entrance vehicles,establish the equal delay model.Use this as a threshold condition for the lane function to change,and verify the reliability of the model by an example.Through the analysis of critical flow value,find that the ratio of left turn flow to total flow of the entrance is between0.27~0.34.The results show that when the proportion of the left turn flow exceeds the critical range,the distribution of the lanes can not meet the turning requirements of left turn traffic flow.And in this time,the function of variable approach lane need to change.Then based on the delay time,the average number of parking and the capacity of the intersection,establish the signal timing model.Then,analyze the control strategy of variable approach lane system,and introduce the trigger time of lane function changing.Based on the model,discuss the control strategy of variable approach lane both in the single and double setting form.According to the number oftraffic flow,this paper discusses the different conditions of low flow and high flow states in each setting form,and formulates different signal control strategies.Finally,evaluate the effect of the control strategy of variable approach lanes under different traffic conditions.In the case of single setting form,select three different optimization schemes to compare and analyze.The results show that the optimization model proposed in this paper has better control effect.In the case of double setting form,two schemes are compared,which are do-not adjusting phase and adjusting phase.It is found that when the two directions are in the state of supersaturation,the improvement effect of adjusting phase is more obvious.