环形快速路交通流的改进元胞传输模型建立与仿真

An Improved Cell Transmission model for Simulation of Traffic Flows of Ring Roads

交通流模型一直是交通系统中最基本的研究内容。适当的交通流模型可用于路网交通流预测和信号控制。以北京环形快速路为背景,采用改进的元胞传输模型(modified cell transmissionmodel,MCTM)进行建模。在MCTM模型中,放宽了原始CTM模型均等划分元胞的限制,并采用密度代替车辆数表示元胞状态,对不同元胞连接方式(简单连接、融合、分离)建立了元胞交通流传输关系。与广泛应用的微观仿真软件Paramics进行了仿真对比分析。结果表明,与原始CTM相比MCTM虽然大大减少了计算复杂性,但仍然可以准确地描述环形快速路交通流动态特性,从而为进一步的交通流预测和匝道控制提供模型基础。

Traffic flow modeling has always been a foundational component of transportation studies. Traffic flow models can be used for forecasting traffic flows and then providing a basis for signal control. In this study, an improved cell transmission model （MCTM） is developed for the ring roads in Beijing. The MCTM removes the restriction of the o- riginal CTM that requires equally partitioning space to develop cells, but it takes density as its state variable, instead of the number of vehicles in the cell. Traffic flow transmission rules between cells are defined for different connection mecha- nisms between cells, including simple connection, merging and diverging. A comparison is made between the simulated results of the MCTM and those from the microscopic traffic simulation model Paramics, The results show that, although it is less complex than CTM in computation, the MCTM still can describe the dynamic characteristics of traffic flow on the ring road accurately and effectively, and can be used in the future for traffic flow forecasting and ramp metering.