考虑交叉口特性的疏散交通路线研究

疏散是应急管理中的重要措施,在应急计划中有必要制定合理的疏散路线以确保疏散车辆尽快到达终点。以往有关最佳疏散交通路线的研究没有考虑交叉口延误和通行能力等因素,若疏散路线经过城市内拥挤路段,忽略交叉口的这些特性会导致结果不尽合理。将交叉口分方向延误和通行能力作为节点权重,建立了点权交通网络,通过在点权网络中求解最小费用流来优化事故地点至安全地点的最佳疏散交通路线及相应的疏散流量,设计了一种最小费用路算法求解该点权网络中的最小费用流。最后以一个数值算例说明了方法的应用,并对考虑和忽略交叉口特性2种情况下得出的路线进行了对比。结果表明该方法能很好地兼顾路网特点和疏散路线优化的要求;若执行忽略交叉口特性的疏散路线方案,极易造成交叉口的拥堵,延长车辆的走行时间。

Optimization of evacuation routes considering movements at intersections

Evacuation plays an important role in emergency management.Efficient tools are needed to produce evacuation route plans that identify routes of evacuation vehicles to minimize the time to evacuate people from affected sources to safety sites.Most research on the optimization of evacuation routes does not explicitly consider intersection movements.However,in congested street networks,turning movement delays traffic and capacity limitations at intersections may be significant,and thus ignoring them may lead to suboptimal or illogical routes.Considering the turning movement at intersections,a special network is constructed with the capacity and delay of intersection movements as the weights.Evacuation routes and the flow assigned to each route considering intersection movements can be obtained by searching the minimum cost flow in such network,with cost representing time.A successive shortest path algorithm is presented to find the minimum cost flow in such network.The validity of the method is demonstrated via a numerical example.The routes obtained for the example,when considering or ignoring intersection movements,are compared and analyzed,which indicates that congestion is quite likely to occur if executing a route plan that ignores movements at intersections.