Research On Priority Control Method Of Bus Signal At Intersection Based On Pre-signal

With the improvement of the national economy and the improvement of the quality of life,the number of motor vehicles has increased year by year,and the traffic congestion has become more and more serious.Bus is an effective way to solve residents’ travel and relieve traffic congestion.Aiming at the priority of the right of way for buses at intersections,this paper adopts the combined model of "entrance channelization design +signal optimization" to further optimize the process of bus parking,queuing,entering and exiting,and improve the efficiency of traffic.First,analyze the current status of bus operation at intersections,and summarize the advantages and disadvantages of different types of intersection bus priority modes,including no bus-only entrance lanes,bus-only entrance lanes,shared lanes for bus and right-turning vehicles,and dedicated phases.There are differences in indicators such as the number of stops,the length of the queue,and the delay among several modes.Summarized the current signal phase inconsistency of bus priority at intersections,insufficient queuing space,and still large delays.Then,the principle of bus priority at intersections based on pre-signal is studied,and the space optimization design and phase optimization design method based on pre-signal are introduced.First,the optimization design of bus pre-signal space.Analyzed the road conditions and facility conditions of the pre-signaling of bus at intersections,combined with the geometric characteristics of the intersection,proposed a "special entrance lane +dedicated queuing space" waiting area channelization program.By analyzing the process of accelerating lane change,decelerating to stop,and stopping queuing,the length of the bus waiting area is determined;the width of the bus waiting area is calculated according to the space requirements of bus and lane change;The impact of the passage of direct buses has determined the form of dedicated lanes for bus sections and the layout of presignal entrance lanes;taking into account the unevenness of bus arrival time,queuing rules for bus waiting areas have been formulated.Second,the phase design optimization method based on pre-signal.Analyzed the coordination relationship between the main signal and the pre-signal,and determined the pre-signal traffic light early time according to the constraints of clearing the waiting area,reducing the effective green light loss time,and secondary parking;analyzed the passengers in ordinary lanes,dedicated lanes,and pre-signal lanes for the total delay,the main signal optimization objective function is determined,and the main signal optimization model is established with the cycle length,minimum green light time,and saturation as constraints,and the genetic algorithm is used to find the optimal solution to the model.Finally,the case analysis and simulation evaluation of the "canalization design +signal optimization" combination mode proposed in this paper are carried out.Use MATLAB software to solve the main signal timing optimization model,and obtain the cycle time of the optimization plan and the green light time of each phase;use the Vissim simulation platform to evaluate the effect of setting pre-signals,and conduct a pre-and post-contrast analysis from the four indicators of vehicle delays,per capita delays,average queue length and average parking times.The results showed that the operating efficiency of bus vehicles at intersections has been significantly improved.Among them,with the pre-signal entrance lane,the average delay of buses and vehicles was reduced by36.3% and 25.4%,respectively.Considering the impact on social vehicles,the average delay of bus passengers + car passengers was calculated,and the average delay per capita was reduced by 28.6% and 18.2%,the average queue length and average number of stops have also been improved to varying degrees.Since this scheme only occupies one straight entrance lane,the impact on social vehicles is small.