将备用能力的概念与城市交通离散网络设计问题结合在一起,一方面通过对路口的信号进行最佳设置使交通网络可以容纳最大的交通需求量;另一方面,通过在交通网络中添加新的路段来提高整个交通网络的通行能力.给出了最优信号控制条件下城市交通离散网络设计问题备用能力的优化模型及其启发式求解算法.最后,通过一个简单的算例,说明该算法是可行并且有效的. The concept of reserve capacity is combined with the problem of discrete network design in urban traffic. On the one hand, the traffic network can accommodate the maximum traffic demand by optimally setting the signal of intersection; on the other hand, by adding new Road segment to improve the traffic capacity of the whole traffic network.An optimization model and its heuristic algorithm for solving the reserve capacity of urban traffic discrete network design under the optimal signal control are given.At last, a simple example shows that the algorithm is Feasible and effective.