关键词: 城市交通, 客货混运, 双目标优化, 开行方案, 货物时效性差异

Abstract: The idle capacity in urban rail transit during off-peak hours offers the potential for passenger-freight mixed transportation. To address the mixed transportation under cross-line operation, this study takes the Y-shaped network as the research object and achieves a cross-line freight transport through trunk-branch line coordination. Building on this, an optimization framework is constructed that integrates the differences in time sensitivity among three cargo types: express, general cargo, and heavy cargo. With minimizing passenger and freight transportation times and operating costs as its two objectives, the model differentiates the departure frequencies for pure passenger trains and three types of mixed trains: passenger-express, passenger general cargo, and passenger-heavy cargo, and uses the ideal point method to convert the bi-objectives into a single objective. To address the nonlinear characteristics of the model, a PCCO-VNS (Passenger-Cargo Coordination Optimization based Variable Neighborhood Search) algorithm is designed, which employs hierarchical passenger-cargo optimization, adaptive neighborhood adjustment, and cargo-priority-oriented repair to improve the search efficiency and solution quality of the algorithm. Case results show that the optimized scheme reduces the comprehensive objective function by 10.00%, passenger waiting time by 11.44%, transfer time by 7.19%, and the platform dwell times for the three cargo types by 10.59%, 16.35%, and 17.79% respectively. Sensitivity analysis indicates that setting the passenger weight to 0.6 achieves a balance between cost control and service level. These findings provide a decision support for the planning and operation of passenger-freight mixed transportation systems under cross-line operation.

Key words: urban transportation, mixed passenger-cargo transport, bi-objective optimization, train operation plan, cargo timeliness differences