Capacity Deterioration with Elastic Demand in Road Segment

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.

摘要道路交通网络脆弱性是道路网络单元遭到突发事件攻击后在路网单元间相互作用以及外界持续影响下引起的路网整体损失的量度。道路交通网络脆弱性评估除了考虑路网内部单元间相互作用外还应考虑路网节点单元的恢复能力。本文在提出路网脆弱性的概念和分析模型的基础上，综合考虑路网结构、交通流运行状态、应急救援点设置等因素，以路网用户最终损失旅行时间为测度进行了路网脆弱性评估，通过一个简单的路网进行了实例分析，并从新建、改扩建道路、改变救援点设置等方面提出了改善的建议。