元胞自动机交通流NS模型相图研究

Study on phase diagram based on NS model

基于开放边界条件下元胞自动机交通流NS模型,模拟入口概率α、出口概率β、车辆最大速度Vmax以及随机慢化概率ρ对系统流量J的影响,根据不同流相中流量J的变化规律,建立NS模型的相图。结果表明,车辆最大速度在一定范围内的增加能提高系统流量,车辆的随机慢化概率在小于临界随机慢化概率ρc时,不会对系统流量造成影响,而超过ρc时,随机慢化概率越大,对系统流量的反作用越明显。Vmax和ρ决定系统相图。当Vmax=5,ρ<ρc时,系统相图只由自由流相和堵塞流相构成,自由流相和堵塞流相被一条曲线分开;ρ>ρc时,最大流相出现,最大流相区域随着ρ增大而增加。

Based on the NS traffic model with open boundary conditions, the influence of the injected probability α, the removed probability β, the maximum velocity Vmax and the randomization probabilities ρ on the flow J is simulated. Then the phase diagrams are constructed due to the change of J in different regimes. Results show that J can be improved along with the increase of Vmax within a certain range. When ρ is smaller than the critical randomization probability ρc , it will not affect J . Whenρexceeds ρc , the bigger the ρ is, the more obvious reaction on J is. Vmax and ρ determinate the phase diagrams. When ρ〈ρc , the phase diagram only consists of the free flow regime and the jamming regime, and the two regimes are separated by a curve. When ρ〉ρc , the maximum current occurs and it will increase with the increase of ρ.