考虑交叉口影响的逆向路段选择优化

逆向车道作为提高路网整体通行能力的一种交通组织策略,已在疏散交通组织中得到了大量应用。以往关于逆向车道设置路段选择的研究,大多没有考虑交叉口影响。在拥挤的城市道路网中,这种忽略会导致过高的预期疏散通行能力估计。本文考虑交叉口影响,建立改进的最大流及其关键边模型,对疏散路网中逆向路段的选择进行优化。将交叉口分转向的通行能力表示为节点的方向性权重,将疏散路网抽象为方向性点权网络。定义该类网络中的最大流增流关键边,即一旦扩容会使网络最大流流值增加幅度最大的边。通过在方向性点权网络中寻找最大流增流关键边,得到考虑交叉口影响时疏散路网中对应的逆向车道设置路段。对经典最大流问题求解算法进行相应的改进,给出方向性点权网络中寻找最大流增流关键边的有效算法,并通过一个数值算例进行测试和仿真分析。结果表明,在考虑交叉口影响的情况下,得到的逆向车道设置路段更为合理,疏散时对其进行扩容能更有效地压缩总疏散时间。

Optimization of the Choice of Contra-flow Links Considering the Influence of Intersections

A reversible roadway (contra-flow) is one in which the direction of traffic flow in one or more lanes is reversed to the opposing direction for some period of time. Reversible lanes have been widely used, especially in recent years, for the evacuation of major metropolitan regions threatened by hurricanes etc. One important problem in the practice of evacuation traffic organization is to choose right road links for contra-flow. Most research on the choice of contra-flow links does not consider the influence of intersections, which may lead to overestimation of evacuation capacity especially in congested urban road networks. An evacuation road network is abstracted as a special network with directional node-weights by considering the capacity of intersection movements as directional weights of nodes. The critical edge for increasing the maximum flow value of such network is defined as the one that can maximize the range of flow value increase by increasing its capacity. Alternative links for contra-flow can be got by searching critical edges in such network. A modified algorithm is presented to find such critical edges on the basis of the maximal capacity path algorithm for the classical maximum flow problem. A numerical example is given and the effects are tested through traffic simulation. It is shown that the results when considering the influence of intersections are more reasonable. The total evacuation time can be compressed more effectively by increasing the capacity of road links when considering the influence of intersections.