信号灯控制下的交通流数值模拟

Numerical Simulation of Light Controlled Traffic Flow

为研究信号灯控制下的交通流特性,利用先前提出的一个改进的NaSch模型对信号灯控制下的单车道交通流进行了建模和模拟,模型中考虑了司机和车辆的敏感性.模拟得到的流量-密度图包括3个不同的密度区域,即畅通交通、饱和交通和拥挤交通.结果显示:当信号周期T小于某个值时,饱和流量随着T的增大而增大,这与大多数微观模型的模拟结果不同.随后通过车辆演化时空图分析了其中的微观机理,得出司机和车辆的敏感性对流量的变化起着重要的作用.同时对交通拥堵特性也进行了研究,表明当处于饱和交通时,信号灯不仅会引起局部拥堵,还会对整体交通造成影响.

In order to investigate the properties of light controlled traffic flow, the traffic flow on a single-lane roadway is studied based on a modified NaSch model proposed by the authors, in which the sensitivity of drivers and vehicles have been taken into account. The flow-density diagrams are obtained and three regions with different traffic density, i.e., the undersaturated traffic, the saturated traffic and the oversaturated traffic, are observed. It is shown that the saturated capacity increases with the increase of cycle time T when T is less than a certain value. This result is different from most microscopic simulations. Then the underlying mechanism is analyzed by taking a deeper probe into the microscopic structure, and the spatial-temporal profiles are described on the basis of the numerical simulation. It is found that the sensitivity of drivers and vehicles plays an important role in the capacity variance. Also the jam transition is investigated, which indicates that traffic lights not only cause the local jam, but also have global effect on the traffic flow when the traffic is in the saturated region.