考虑风险取向差异的混合用户平衡模型

Mixed User Equilibrium Model Considering Travelers'Difference in Risk Taking Behaviors

为准确描述随机路网环境下出行者的择路行为,提出了考虑风险取向差异的混合用户平衡模型。根据风险取向不同,将出行者分为冒险型、中立型、保守型和超保守型,并考虑了出行者对出行时间的估计误差、路网服务水平对需求量的影响及路网拓扑关系等影响配流的关键因素。推导了需求服从对数正态分布、路段通行能力服从贝塔分布条件下,各类出行者出行成本的计算公式,建立了用等价变分不等式表示的平衡模型。研究结果表明:出行者的风险取向对配流结果会产生重要影响;随着需求水平的提高和路段通行能力退化程度的加剧,不同风险取向出行者具有不同择路倾向,冒险型出行者倾向于选择出行时间波动大的路径,中立型出行者选择期望出行时间最小的路径,保守型和超保守型出行者倾向于选择出行时间波动小的路径。

In order to precisely depict travelers＇ path choice behaviors in a stochastic road network, a mixed user equilibrium model considering travelers＇ difference in risk taking behaviors was proposed. In the model, the travelers were classified as risk-prone travelers, risk-neutral travelers, risk-averse travelers and extremely risk-averse travelers from the perspective of risk taking behaviors, and the key factors for traffic assignment including travelers＇ perception errors on travel time, the influence on traffic demand caused by the road network service level, and the road network＇s topological relationship were explicitly taken into account. The calculation formulas for the travel costs of four types of travelers, with traffic demand following log-normal distribution and link capacity following Beta distribution, were derived, and user equilibrium model, formulated as an equivalent variational inequality, was built. The results show that travelers＇ risk taking behaviors will have significant influence on the results of traffic assignment. As the demand level and the degradation degree of link capacity increase, different travelers will have different path choice behaviors. Specifically, risk-prone travelers prefer to choose the paths with higher fluctuation of travel time, risk-neutral travelers prefer to choose the paths with minimum mean travel time, while risk-averse travelers and extremely risk-averse travelers tend to choose the paths with the lower fluctuation of travel time.