Abstract
Effective railway freight transportation relies on a well-designed train service network. This paper investigates the train service network design problem at the tactical level for the Chinese railway system. It aims to determine the types of train services to be offered, how many trains of each service are to be dispatched per day (service frequency), and by which train services shipments are to be transported. An integer programming model is proposed to address this problem. The optimization model considers both through train services between nonadjacent yards, and two classes of service between two adjacent yards ( i.e., shuttle train services directly from one yard to its adjacent yard, and local train services that make at least one intermediate stop). The objective of the model is to optimize the transportation of all the shipments with minimal costs. The costs consist of accumulation costs, classification coststrain operation costs, and train travel costs. The NP-hard nature of the problem prevents an exact solution algorithm from finding the optimal solution within a reasonable time, even for small-scale cases. Therefore, an improved genetic algorithm is designed and employed here. To demonstrate the proposed model and the algorithm, a case study on a real-world sub-network in China is carried out. The computational results show that the proposed approach can obtain high-quality solutions with satisfactory speed. Moreover, comparative analysis on a case that assumes all the shuttle train services between any two adjacent yards to be provided without optimization reveals some interesting insights.
Highlights
Railway freight is an important logistical system supporting both global and regional economies
(2) An optimization model for the problem of train service network design is proposed with respect to minimizing car-hour consumption across all the yards in the railway network
Consider as an example the cars going from yard 2 to yard 9: they are rstly classi ed at yard 3, where they are merged with cars traveling from yard 3 to yard 9; these cars are reclassi ed at yard 8, and merged with cars from that yard going to yard 9; the nal leg is the local service from yard 8 to yard 9
Summary
Railway freight is an important logistical system supporting both global and regional economies. (2) An optimization model for the problem of train service network design is proposed with respect to minimizing car-hour consumption across all the yards in the railway network. Represents accumulation car-hour costs when a shuttle and a local train service are dispatched simultaneously between two adjacent yards; in this case, the shipments between two adjacent yards are transported by the shuttle train service. Considering that the rst classi cation yard of cars between two yards is an integer value, it is convenient to implement encoding in a genetic algorithm, which is applied here to solve the model. (4) Penalty function: e penalty function guarantees that the constraints (formulae 5 and 8) are satis ed
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