考虑时空相异的危险品运输车辆安全调度

为确保危险品运输车辆间的安全距离, 从时空角度优化了危险品运输车辆的行驶路径和发车时间间隔; 分析了危险品运输车辆发生事故对其他车辆的影响及其与时空距离的关系, 提出了危险品运输车辆间时空安全距离评价方法, 并以时空安全距离为约束, 提出了车辆安全出发时间间隔计算方法; 建立了满足时空相异约束的危险品运输车辆调度模型, 设计了用于生成车辆调度时刻表的两阶段求解方法, 第1阶段采用NSGA-Ⅱ算法优化车辆行驶路径, 第2阶段分别设计了遗传算法和基于插入思想的近似算法以优化发车时间间隔; 为了验证车辆调度模型与算法的有效性, 对比了每个阶段中不同算法的优劣, 并分析了危险品事故影响系数和事故影响接受度对车辆调度结果的影响。研究结果表明: 提出的方法可针对不同危险品事故影响系数获得危险品运输车辆调度时刻表, 生成的车辆调度时刻能够保证车辆在行驶过程中始终保持安全距离; 遗传算法和近似算法获得的平均运输总时间分别为2.45和2.49 h, 表明近似算法获得的解劣于遗传算法, 但运行时间仅为遗传算法的1/10 000~1/5 000;危险品事故影响系数或事故影响接受度越小时, 车辆发车时间间隔越大, 导致运输总时间变长; 考虑时空相异性的车辆调度可以弥补相异路径方法仅从空间上考虑相异性的不足, 同时能够避免采用相异路径方法可能遗漏最佳运输路径的问题。 

Safety scheduling of hazardous materials transportation vehicle considering spatio-temporal dissimilarity

To ensure a safety distance between the hazardous materials transportation vehicles, the travel routes and departure time intervals of hazardous materials transportation vehicles were optimized in term of space-time. The impact of hazardous material transportation vehicle accident on other vehicles and the relationship between the hazardous material transportation vehicle accident and the spatio-temporal distance were analyzed, an evaluation method of spatio-temporal safety distance between vehicles was proposed, and taking the spatio-temporal safty distance as a constraint, the calculation method of vehicle safety departure time interval was proposed. A scheduling model of hazardous material transportation vehicle satisfying the spatio-temporal dissimilarity constraint was established. A two-stage solution method was designed to generate the vehicle scheduling timetable. The NSGA-Ⅱ optimization algorithm was used to optimize the travel route of vehicle at the first stage. The genetic algorithm and approximation algorithm based on the inserting thought were designed to optimize the departure time interval at the second stage. To verify the effectiveness of vehicle scheduling model and algorithm, the advantages and disadvantages of different methods at each stage were compared, and the influences of hazardous material accident impact factor and accident impact acceptance on the scheduling results were analyzed. Research result shows that the proposed method can obtain hazardous material transportation vehicle scheduling timetables with different hazardous material accident impact factors, and always ensure the vehicles a safe distance during driving. The average total transportation times obtained by the genetic algorithm and approximation algorithm are 2.45 and 2.49 h, respectively, indicating that the optimal solution of approximation algorithm is inferior to that of genetic algorithm, but the run time is only 1/10 000-1/5 000 of that of genetic algorithm. The smaller the hazardous material accident impact factor or the accident impact acceptance, the larger the vehicle safety departure time interval is, which leads to a longer total transportation time. The vehicle scheduling considering the spatio-temporal dissimilarity can compensate for the deficiency of dissimilar routing method only considering the spatial dissimilarity. At the same time, using the dissimilar routing method can prevent the problem of missing the optimal transportation route.