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为评价道路网络性能所具有的在不确定性,提出一种基于灵敏度分析的模拟方法,以分析随机网络中路段流量的波动特性。将路径选择分散参数假定为一个正的随机变量,以反映在不确定环境下出行者路径选择行为的随机特性。对于任一个路径选择分散参数随机变量的实现,用基于Logit的随机用户平衡获取对应的路段流量,从而得到随机路段流量的分布特性。为避免重复求解随机用户平衡问题,建立随机用户平衡路段流量关于路径选择分散参数的偏导数公式并用于随机用户平衡路段流量的估计。计算这些偏导数的一个关键是有效求得路段使用概率。分析解决了采用Dial算法计算路段联合使用概率时的路径集一致性问题。用一个算例对所提出的方法的可行性进行了说明。
In order to evaluate the uncertainty of road network performance, a simulation method based on sensitivity analysis is proposed to analyze the fluctuation characteristics of road traffic in random networks. The path selection scatter parameter is assumed to be a positive random variable to reflect the random characteristics of the traveler’s path selection behavior in uncertain environment. For any random selection of distributed routing variables, Logit-based random user equilibrium is used to obtain the corresponding link traffic, and the distribution of random link traffic is obtained. In order to avoid the problem of repeated user equilibrium, a formula for partial derivative of the path parameter of the random route balancing is established and used to estimate the traffic of the random segment. One of the keys to calculating these partial derivatives is to find the probability of using the link effectively. This paper analyzes and solves the consistency problem of path set when using Dial algorithm to calculate the joint use probability of road segments. An example is given to illustrate the feasibility of the proposed method.