基于交通实测的交通流密度特性分析

Density Property of Traffic Flow based on Traffic Measurement

为揭示交通流密度的本质特征,对上海延安高架和郑州金水路高架上交通流实测密度值进行了统计分析.利用贝塔函数对数据进行曲线拟合,得出了车辆密度的概率密度分布基本符合贝塔分布的结论;进而基于Na Sch元胞自动机交通流模型,考虑车辆密度的概率密度特征,通过数值模拟得到了交通流的流量—密度图,呈现出一个二维分布的区域,与实测结果吻合良好,进一步验证了车辆密度的概率密度特征.结论可为交通流建模以及交通工程的规划和管理提供理论参考.

The probability density characteristic of the vehicle density is investigated based on the empirical data obtained from the Yan＇an Elevated Road of Shanghai and Jinshui Elevated Road of Zhengzhou, for the purpose of exploring the properties of traffic density. It is found that the probability densities of the vehicle density agree well with the Beta function by means of curve fitting. Taking the properties into account, the numerical simulation is carried out based on the NaSch model. The result is obtained in the form of the flux-density diagram. It is shown that the steady state of the congested traffic occupies a two-dimensional region in the flow-density plane, and is in much better agreement with the traffic measured data. In so doing, the probability density characteristic of the vehicle density is thus reconfirmed.