Signal Cooperative Control Based On Mixed Traffic Supply And Demand On A Single Intersection

The increasing travel volume has intensified the contradiction between demand and supply of mixed traffic flow on a single intersection,accompanying with unreasonable resources allocation,making traffic issues including traffic congestion and traffic chaos caused by human-vehicle conflict increasingly severe.Traffic signal control which plays a crucial role in regulating the release of traffic flow in short term can reasonably allocate green resources according to the actual state on a single intersection to effectively improve the releasing efficiency of mixed traffic,as well as alleviate traffic congestions.However,the existing research on traffic signal optimization generally adapts the control strategy merely based on vehicle demand,taking insufficient account of the reality that there exits supply ceiling in the exit lane and pedestrians’ crossing demand is hardly fully met,which is easy to lead to queue spillbacks and human-vehicle conflicts in the application.Although progress has been made in research on the supplydemand traffic signal optimization at present,resources are still not optimally allocated on a single intersection because low attention has been paid to pedestrians’ crossing needs.Therefore,it is urgent to carry out research on the optimization method of mixed traffic flow control on a single intersection under the framework of supply and demand cooperation,so as to achieve a reasonable and efficient allocation of resources which can improve the operation efficiency and safety level on a single intersection.In order to meet the requirement of maintaining the efficient and safe operation of mixed traffic flow on a single intersection,a supply-demand cooperative signal control idea is put forward in this paper.A signal control system has been constructed according to the supply-demand cooperative control process of mixed traffic flow on a signalized intersection.On this basis,to represent the problem of signal cooperative control based on mixed traffic flow supply and demand on a single intersection,time-varying calculation models of mixed traffic supply and demand have been constructed,and mixed traffic supply matrix,demand matrix,green time matrix and other matrixes have been introduced in the same time.In order to obtain the global optimal solution of signal scheme under the cooperative constraint of supply and demand,the problem of supply-demand cooperative signal control optimization of mixed traffic flow on a single intersection is simplified to the optimization problem of basic signal parameters which include phase,phase sequence and timing.To construct the signal control optimization model,an expression form of variables is put forward based on the Ring-Barrier phase structure,constraint conditions are established according to the requirements of supply-demand cooperative and RingBarrier phase structure,and release efficiency of mixed traffic flow is selected as the target.Considering the advantage of particle swarm optimization in solving large-scale problems and the disadvantage of easily falling into local optimum,an improved particle swarm optimization algorithm based on the adaptive adjustment method of population size and inertia factor is selected to solve the optimization model.According to the optimization model and the particle swarm optimization process,the representation of particle individuals and functions of search space and fitness are built to achieve a fast solution of signal control problem.To validate the optimization model,simulation experiments are carried out in six mixed traffic flow situations which are set up according to the diverse states of vehicles and pedestrians.The convergence results show that the algorithm can achieve fast convergence under different mixed traffic flow conditions on a single intersection.And the optimized model presented in the paper is compared with two other signal control models which include control model based on mixed traffic supply and signal cooperative control with vehicle supply and demand model in six mixed traffic flow situations.The comparative experimental results show that the optimization model can not only effectively avoid queue overflow and human-vehicle conflict,but also improve the mixed traffic release and delay to some extent.The optimization of mixed traffic flow control method on a single intersection put forward in this paper from the perspective of supply and demand cooperation can not only effectively avoid spillbacks but also improve low resource utilization rate,providing a new research idea for improving the operation efficiency and safety level when mixed traffic crossing a single intersection.