Improving the Operational Reliability of Scheduling and Routing for Multi-Type Freight Locomotives

The emergencies caused by some factors that would interfere with freight locomotives to accomplish train services on time and result in the delay of subsequent train services as well as failures of locomotive scheduling and routing. It is actually necessary to formulate a high-reliable daily working diagrams for locomotives, which can adapt to uncertain environment changes. Through the assumption that the delay time of the trains follows the negative exponential distribution, this paper analyzes the connection reliability of the adjacent train services once a train is delayed. The problem is then transformed into a multiple traveling salesman problem (MTSP) considering some complicated constraints including multi-type locomotives, train services and maintenance tasks, etc. The proposed model aims to minimize the total operational costs of locomotives. The ant colony algorithm is developed to solve the proposed model. A case study is finally given to verify the validity and effectiveness of the proposed model and algorithm.