路径选择准则对随机供需路网运行效率的影响

The influence of route choice criteria on the operating efficiency for road network with stochastic supply and demand

为研究不同路径选择准则对随机供需路网运行效率的影响,在假定需求服从对数正态分布、容量服从Beta分布的前提下,构建了三种路径选择准则:期望行程时间最短、行程时间预算最短以及超预算期望行程时间最短。基于这三种准则,分别构建了相应的交通分配变分不等式模型,并设计了求解算法。从交通周转角度出发,提出了路网运行效率的测算方法。通过算例分析,探讨了三种路径选择准则以及路段容量降级程度、需求结构、需求总量和行程时间可靠度对路网运行效率的影响。研究结果表明:期望行程时间最短择路准则下的路网运行效率最高,而超预算期望行程时间最短准则下的路网运行效率最低;无论采用哪种择路准则,路网运行效率均随路段容量降级程度的增加而显著下降;当路段容量降级程度与需求的“均值-方差比”一定时,在三种路径选择准则下,均存在一种特定的需求结构与总量,使运行效率达到最大值;在行程时间预算和超预算期望行程时间最短准则下,路网运行效率随行程时间可靠度的增加而显著下降。

To investigate the impact of different route choice criteria on the operational efficiency of road networks,three criteria based on mean travel time,travel time budget,and mean-excess travel time are established,assuming that OD(origin-destination)demand follows a Log-normal distribution and link capacities follow a Beta distribution.Traffic assignment variation inequality models are constructed according to those criteria,and algorithms are developed to solve them.From the perspective of traffic turnover,a calculation method for road network operating efficiency is proposed.The influence of three route choice criteria,degree of link capacity degradation,demand structure,demand quantity,and travel time reliability on road network operating efficiency are analyzed through case studies.The results show that:1)Road network operational efficiency is highest under the mean travel time(MTT)criterion and lowest under the mean-excess travel time(METT)criterion;2)Operational efficiency decreases notably as link capacity degradation increases;3)There exists a specific demand structure and volume that maximizes operational efficiency under each criterion when the degree of link capacity degradation and demand mean-variance ratio are fixed;4)For travel time budget(TTB)and METT route choice criteria,operational efficiency decreases significantly as travel time reliability increases.