交通运输工程与信息学报

【背景】城市轨道交通线路平峰时段客流需求较少、发车间隔较大，利用其富余能力提供货物运输服务可有效提升线路经济效益，缓解道路货运压力。【目标】针对城市轨道交通线路双方向货运需求，在客运列车时刻表不变的条件下，通过增开大、小编组货运列车进行货物运输。针对列车灵活编组，货运列车可在线路终点站通过解编、连挂作业进行编组转换。【方法】以货运列车的时刻表、编组形式、车底周转计划和货单分配方案为决策变量，考虑列车运行间隔、列车容量、装卸作业时间、车底周转、货物运输时效性等约束，构建以货运净收益最大为目标的城市轨道交通货运列车运行计划优化模型。【数据】以某城市轨道交通线路为例创建了50个订单规模的算例，以验证模型的有效性，并分析灵活编组的优势和适用性。【结果】案例分析表明，考虑可变编组模式可更好地满足线路货单需求，且相较于固定多编组模式可以使货运利润提升1.29%。灵敏度分析表明，当货运列车满载率到达60%～70%、上行和下行方向货运需求存在一定量的差值、货单运输时效性要求高时，采用可变编组模式的优势更为明显，但当编组转换的解挂编成本增加时，采用可变编组模式的效果下降。

[Background] Urban rail transit lines often experience low passenger demand and long departure intervals during off-peak hours. Utilizing the surplus capacity of these lines for freight transport can enhance economic efficiency and reduce the burden on road freight systems. [Objective] This study proposes a freight transport strategy for bidirectional urban rail transit lines, which involves operating additional freight trains with both large and small compositions, while maintaining the existing passenger train timetable. A flexible composition approach is introduced, enabling freight trains of different sizes to be coupled or uncoupled at terminal stations to carry out freight tasks in opposite directions. [Method] The optimization model aims to improve freight train service planning based on a flexible composition mode. It is developed with the objective of maximizing freight profit by determining the train timetable, train composition, rolling stock circulation plans,and shipment allocation plans for freight trains. The proposed method considers constraints such as train operation intervals, train capacity, loading/unloading time, rolling stock circulation, and freight transportation time requirements. [Data] A simulation instance with 50 freight orders, based on a real urban rail transit line, was created to evaluate the performance of the model and to assess the benefits and feasibility of the proposed flexible composition strategy. [Results]The case study of an urban rail transit line demonstrates that the flexible composition mode proposed in this paper better meets the cargo demand along the line. Compared with the fixed composition mode of multiple-unit trains,the flexible composition mode increases cargo profit by 1.29%. Sensitivity analysis shows that when the full load rate of freight trains reaches 60%～70%, when there are significant differences in freight volume between the up and down directions, or when freight transportation time requirements are stringent, the advantages of the flexible composition mode become more apparent. However, as the cost of train composition and decomposition increases, the effectiveness of the flexible composition mode decreases.