冰雪条件下城市路网容量可靠性

Urban road network capacity reliability under ice and snowfall conditions

为研究冰雪条件下城市路网容量可靠性,采用路段行程时间可靠性及容量为约束条件进行研究.定义了冰雪条件下的路网容量可靠性概念,以BPR(Bureau of Public Roads)函数为基础,通过引入自由行程时间及通行能力修正函数,建立了适用于冰雪条件的ISB-BPR(Ice and Snowfall Based-Bureau of Public Roads)函数,并以路段容量和遵循ISB-BPR函数的行程时间可靠性作为约束条件构建了上层规划,以符合冰雪条件出行特征的弹性需求分配模型作为下层规划,提出了适用于冰雪条件的双层规划模型.根据模型反映的路径选择行为特点,设计了灵敏度分析法求解交通量分配模型,以Monte Carlo仿真算法求解路网容量可靠性.并给出1简单算例,计算结果表明:冰雪强度及交通供需对冰雪条件下路网容量可靠性有很大影响.该模型能够用于评估冰雪条件下的路网性能,并为路网规划、设计、维护提供依据.

To develop an approach to evaluate the capacity reliability of road network based on ice and snowfall conditions,the capacity reliability was studied on the basis of travel time reliability and capacity of links.The concept of network capacity reliability was proposed.Through the introduction of free travel time and capacity correction functions for Bureau of Public Roads （BPR） model,an Ice and Snowfall Based-Bureau of Public Roads （ISB-BPR） function was proposed.Then the bi-level programming model of road network capacity reliability was developed.The travel time reliability and link capacity as restrictions were proposed in the upper programming model.To follow the characteristics of route choice under ice and snowfall conditions,the elastic demand user equilibrium （EDUE） was set up in the lower programming model.An assessment methodology integrating sensitivity analysis of EDUE and Monte Carlo simulation was proposed to evaluate the capacity reliability.A numerical case was also given to demonstrate the practicality of the given model.The results show that the ice and snowfall intensity,traffic supply and demand all have great influence on the capacity reliability.The methodology is useful and applicable.It may provide a basis for network planning,design and maintenance.