随机时间依赖路网中危险品运输路径多准则优化

为实现动态路网中的危险品运输路径优化,以期为运输商的路径选择提供决策支持,分析了运输网络的随机时间依赖(STD)特征,对分段连续时间区间内各路段的行程时间和受影响人数进行曲线拟合.考虑到达时间窗的约束,以行程时间和运输风险的随机属性值为优化准则,建立0-1整数规划模型.结合STD网络的FIFO性质设计了两阶段多维标号修正算法,得到不同出发时刻以给定置信水平满足时间窗约束的非支配路径集合,并提出准则权重和阈值支配方法,实现计算效率和求解质量的均衡.研究结果表明:危险品在STD路网中的行程时间和运输风险与到达时间窗的设置和出发时刻的选取有关;生成的非支配路径取决于出发时刻和运输商的选择偏好,非支配路径的数量取决于支配阈值的大小;不同类型运输商可根据准时到达置信水平来选择出发时刻与运输路径的最优组合.

Multi-criterion path optimization for hazardous materials transportation in stochastic time dependent road networks

To optimize the hazardous materials (hazmat) transportation paths in dynamic road networks and make a decision on path selection for carriers, the stochastic time dependent (STD) characteristics of transport networks were analyzed, the travel time and the number of people affected around each link were fitted in piece-wise continuous time interval. The 0-1 integer programming model was formulated by taking the arrival time window as a constraint, and taking the stochastic attribute values of travel time and transport risk as optimization criteria. A two-stage multi-dimensional label correcting algorithm was designed with First-In-First-Out property of the STD road networks, and the non-dominated paths were generated at different departure time to meet the time window constraint with predetermined confidence level. The criterion-weight and threshold-dominate methods were proposed to balance computational efficiency and accuracy. Research results indicate that the travel time and transport risk of hazmat in STD road networks are related to the setting of arrival time window and the selection of departure time. The non-dominated path depends on the departure time and the choice of carrier''s preference, and the amount of non-dominated paths depends on the dominated threshold value. Different types of carriers can choose the optimal combination of departure time and transportation path according to the confidence level of arriving on time.