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城市道路网运行中受多种因素干扰，系统运行经常处于非稳定状态，出行者不仅要求尽量减少出行时间，而且越来越重视保障出行时间的稳定性、强调交通系统的可靠性.考察智能交通系统中人们出行选择的偏好，80%以上的通勤者认为行程时间可靠性是他们出行时第一或者第二位的要求，因此，本文以行程时间可靠性和行程时间作为出行者路径选择的两个主要因素,建立混合随机路网模型.借鉴随机平衡分配模型的求解方法，设计混合随机路网模型的求解算法.同时，通过熵来考察行程时间可靠性和行程时间在出行者路径选择中所占比例不同对道路网交通状态的影响.此模型可描述智能交通系统下，有无信息出行者的比例对路网交通状态的影响.通过案例研究发现，只有拥有信息的出行者比例达到一定程度时,路网才最稳定.

Stochastic Road Network Model and Network Stability Analysis

The sources of disruption to road network are numerous and travelers expect not only less travel time but also high reliability under the uncertainty of travel.More than 80 percent of commuters’ route choices rely on travel time reliability as their primary or second factor according to an route choice investigation.Therefore,the combined stochastic road network model is proposed in this paper which adapts travel time reliability and travel time as the main factors to make route choice.The algorithm can be obtained to solve the proposed model with the help of the stochastic user equilibrium(SUE) model.Meanwhile,the entropy can be obtained to show the stability of road network according to the ratio of travel time reliability and travel time among route choice.These are reminiscent of the situation in ITS where users having information care more about travel time reliability and others having no information emphasize on travel time.An example is illustrated and the road network is more stable when the ratio of the user having information reaches a certain value.