弹性需求下路段通行能力的退化状态分析

Capacity Deterioration with Elastic Demand in Road Segment

基于行程时间对交通需求的影响,建立路段交通流模型,对路段交通流量稳定性及通行能力的退化状态进行分析.在出行者的交通需求具有弹性的情况下,路段行程时间越长,交通需求越低.模型中行程时间由道路上的交通状态决定,车辆行驶过程的计算利用MITSIM模型,通过数值模拟方法分析弹性需求对交通流的稳定性及通行能力的影响.仿真结果表明,在交通需求和路段性能相互作用下,路段交通流量趋向于稳定,非饱和状态下的稳定流量随着交通压力的增加逐渐上升到最大通行能力,而饱和状态下的稳定流量小于最大通行能力且交通压力越高通行能力退化越严重.因此在城市路网规划时,应综合考虑路网中各路段通行能力,避免路段通行能力下降.

To explicitly analyze the stability of traffic flow and the capacity drop, the paper develops a link traffic simulation model based on the elastic demand depending on travel time. The traffic demand decreases when the travel time is prolonged under the elastic traffic demand. The travel time lies on the traffic condition of road segment, and the traffic state is evaluated with the MITSIM model. The results show that the link flow will be stable under the natural restrictions of traffic demand and travel time. The unsaturated stable flow will reach the maximum capacity with the traffic pressure boost. The saturated stable flow will below the maximum capacity and the flow volume will decrease with the increase of traffic pressure. To avoid the travel capacity reduction, all the link capacities should be considered in traffic planning for the entire transport network.