Periodical Rail Inspection Scheduling in Railroad Networks

Railroads use a set of rail inspection teams to periodically examine the status of rail tracks across the railroad network, so that rail defects can be identified and repaired before potential train accidents can occur. The rail inspection scheduling problem (RISP) is a large-scale routing and scheduling problem where thousands of inspection tasks are to be scheduled subject to many complex side constraints such as periodicity constraints and discrete working time constraints. This paper proposes a vehicle routing problem formulation for RISP and a customized heuristic solution algorithm. The algorithm iteratively applies a constructive heuristic and a local search algorithm in an incremental scheduling horizon. The proposed model and algorithm have been adopted by a Class I railroad for field implementations, and real-world case studies show that the proposed approach significantly outperforms the state-of-art manual solution approach. The proposed model can also be used to provide managerial insights and answer long-term resource planning questions.