Integrated optimization of railway freight service: express trains and ordinary trains

Currently, in the process of rail cargo transportation, except for entire trains for bulk cargo, the operation plan of express trains is always provided firstly, and then, the formulation of ordinary trains is determined. However, this way does not take into account the attraction of cargo flow between the two services and does not correspond to actual requirements. Therefore, an integrated optimisation model of railway freight service is proposed to determine which freight train service should be provided between which stations and which shipment assigns to which freight service, including express and ordinary trains. The objective aims to maximise the total revenue of carrier; also, the additional service fee of direct express trains is added to the objective system. For the carrier, it only needs to deliver the cargos to destination before the transportation due date; thus, this model includes the due date constraint requested by shipper. Moreover, a test instance is accomplished to prove the validity of method, and a real instance is constructed, the results of which show that an optimal solution of 268,846.47 CNY can be obtained in acceptable time. Finally, the method proposed in this study can provide theoretical support for the decision-making of railroad management department.