Strategic Gang Scheduling for Railroad Maintenance

We address the railway track maintenance scheduling problem. The problem stems from the significant percentage of the annual budget invested by the railway industry for maintaining its railway tracks. The process requires consideration of human resource allocations (gangs), as well as effective logistics for equipment movement and routing around the rail network under time window constraints. We propose an efficient solution approach to minimize total costs incurred by the maintenance projects or jobs within a given planning horizon. This is accomplished by designing a job-time network model to capture feasible schedules under the constraints of job precedence and developing a mathematical programming heuristic to solve the underlying model. The key ingredient is an iterative process that extracts and then re-inserts jobs based on an integer programming model. Computational experiments show the capability of the proposed heuristic to schedule more than 1,000 jobs and more than 30 gangs.