元胞自动机交通流模型中的车辆更新方式研究

STUDY ON VEHICLES REPLACEMENT PROCEDURES IN CELLULAR AUTOMATA MODEL OF TRAFFIC FLOW

基于TASEP(Totally Asymmetric Simple Exclusion Process)模型,使用蒙特卡洛方法模拟开放边界条件下不同车辆更新方式对稳态时车辆特性及相变行为的影响,得到不同注入概率α和输出概率β条件下的交通流基本图。结果表明,不同更新方式对系统的稳态特性及相变行为有较大影响,流量和密度随α和β的不同而变化,模拟结果与解析解吻合。随机更新方式下道路车流量的大小由输出概率决定,当输出概率达到一定值时,它的增大无法提高道路上的车流量;顺序更新方式的优点是仅当输入和输出概率都相等时,系统保持畅行相;而局部并行更新方式下得出的相图则与顺序和全局并行更新这两种方式下得到的相图类似且可以更好地反映交通流现实。

Based on TASEP model,we use Monte Carlo method to have simulated the impact of different vehicle replacement procedures under the condition of opened boundary on vehicle properties and phase transition behaviour in steady-state,and get the fundamental traffic flow diagrams on conditions of different injected probability α and removed probability β.The results show that,different replacement procedures have great influence on steady-state properties and phase transition behaviour of the system,the flow and density change along with the variation of α and β,the simulation results coincide with the analytical solutions.In random replacement procedure the value of traffic flow on the road is determined by the removed probability,when the removed probability β reached a certain value,its increase would be unable to improve the traffic flow on the road; For the replacement procedure in ordered sequence,its advantage is that only when the injected and the removed probabilities are equal,the system can then remain free flow; while the phase diagram derived from local parallel replacement procedure is similar to the phase diagrams obtained in ordered sequence and global parallel replacement,and can better reflects the real conditions of traffic flow.