Optimization of Simultaneous Delivery and Pickup Wagon Scheme on Hybrid Siding Network of Railway Terminal

Aiming at the local freight train transit system in railway terminal, the optimization of simultaneous delivery and pickup wagon scheme on hybrid siding network is presented. The problem is formulated as a mathematical programming model. The objective function intends to minimize shunting engines’ operating cost, wagons’ travelling cost, and penalty cost for exceeding the retrieval time window. Some constraints indicating the relationship between delivery and pickup wagons, relationship between radial branches and operation batches, relationship between local wagon groups’ retrieved time and outbound train departure time, and relationship between tasks and operation batches are considered in the model. As an NP problem, using traditional method to solve the model is difficult and inefficient. A novel two-stage hybrid optimization procedure is proposed. Firstly, the three-phase approach composed of coding task sequence, dividing task batch, and generating access order sequence population is developed to generate initial solution. Secondly, an asynchronous iteration heuristic is provided. The iteration object is given as the expression form of the solution representing the delivery and pickup wagon sequence and then the initial iteration population is generated. Furthermore, the primary updating iteration population with pending and remaining groups is introduced to optimize iteration object Then, the senior updating iteration population with Lévy flight searching is also introduced to optimize further iteration object. Finally, the experimental scenarios are designed to test the proposed approach. Also, the proposed approach is compared with some other approaches and the performance of the proposed approach is evaluated by some different sized instances.