基于精细微观交通流模型的信号交叉口人-车相互干扰研究

Pedestrian-vehicle interference at a signalized crossing based on detailed microscopic traffic flow models

采用微观离散模型研究信号交叉口的人-车相互干扰机理,其中车辆运动描述基于细化NaSch模型并考虑了司机对交通灯信号切换的预期效应;行人运动描述则基于多步格子气模型并考虑了过街绿灯周期内行人过街速度逐渐增加的特征.机动车与行人之间相互干扰表现为交通灯信号切换时由于车辆(行人)滞留冲突区而造成行人(车辆)运动的延误.通过数值模拟得到了车辆运动的基本图、行人等待时间以及相应的相图,并给出行人(车辆)滞留冲突区内造成车辆(行人)延迟的定量特征.模拟结果发现存在一个临界绿信比.当绿信比小于临界值时,随着密度的增大,车流出现自由流相、饱和流相和拥堵流相;而当绿信比大于临界值,则出现自由流相、共存相、饱和流相和拥堵流相.由人-车相互干扰所导致的延误与车流和行人流的运行状态密切相关.当行人到达率和绿信比都比较大时,等待区内的行人无法在行人绿灯周期内一次清空.文中详细地讨论了人-车相互干扰的定性和定量特征.发现通过合理设置绿信比,可以在保证车流运行效率的同时,减少行人过街的等待时间.

Interference between pedestrians and motor vehicles at signalized intersections not only leads the traffic to delay and traffic efficiency to decrease,but also induces traffic crashes to happen frequently.In this paper,a microscopic discrete model for traffic flow is adopted to study the mutual interference mechanism between pedestrians and vehicles at signalized intersection.The vehicular traffic flow model is based on the refined NaSch model,and traffic lights are introduced to consider the driver anticipating in traffic signal switching.Based on the multi-step lattice gas model,the pedestrian flow model considers the fact that the pedestrians’speed increases gradually during pedestrian cross-street green time.Both models reflect real features of movement of vehicles(pedestrians)in daily life.When the traffic light signal switches,the vehicles(pedestrians)staying in the conflict area result in the delay of pedestrians(vehicles).It is assumed that pedestrians and vehicles cannot coexist in the conflict area at the same time.In the simulation,the periodic boundary condition is applied to the lane,and the open boundary condition is applied to the crosswalk.The arrival rate of pedestrian is assumed to satisfy the Poisson distribution.Both the fundamental diagram of vehicular traffic flow and the pedestrian waiting time are calculated,and the phase diagram revealing the global nature of the presented model is obtained accordingly.The quantitative characteristics of vehicle(pedestrian)delay time caused by pedestrians(vehicles)staying in the conflict area are given as well.Simulation results show that there is a critical split.When the split is less than the critical value,three kinds of traffic phases,i.e.,free flow phase,saturated flow phase,and jamming flow phase,appear with the increase of density.When the split is larger than the critical value,four kinds of traffic phases,i.e.,free flow phase,coexisting phase,saturated flow phase,and jamming flow phase are distinguished.The delay caused by the mutual interference between pedestrians and motor vehicles is closely related to the state of vehicle flow and the state of pedestrian flow.When the arrival rate of pedestrians is quite large and the split is large enough,these pedestrians in the waiting area cannot be emptied once in a single pedestrian cross-street cycle.The qualitative and quantitative characteristics of mutual interference between pedestrians and vehicles are discussed in more detail.The setting of a reasonable split not only ensures the efficiency of traffic flow,but also reduces the waiting time of pedestrians to cross the street.