1模型 1.1城市交通网的结构设城市交通网由有向图G=(N,A)表示;其中N为节点集,A为有向弧集。在以往的文献中,节点代表道路交叉口、居民集中区等;有向弧代表路段。在交通分配中,则把交叉口费用视为常数或者干脆不考虑;这种处理方法,在交通规划中是可以的,而在交通管理中,它和实际情况存在较大差 1 Model 1.1 Structure of Urban Traffic Network The urban traffic network is represented by a directed graph G = (N, A); where N is a node set and A is a directed arc set. In the past literature, nodes represent road intersections and residential areas; arcs represent sections. In the distribution of traffic, the cost of the intersection is considered as a constant or not considered at all. This method of handling can be used in traffic planning. In traffic management, there is a big difference from the actual situation