A Mathematical Approach for Reducing the Maximum Traction Energy : The Case of Korean MRT Trains

This paper describes a reduction in the peak traction energy of mass rapid transit (MRT) railways through timetabling. We develop a mixed integer programming (MIP) model that minimizes the maximum traction energy that occurs when trains are running simultaneously. We tried two approaches. In the first approach, we use the commercial MIP solver CPLEX. In the second approach, we propose a heuristic algorithm. We applied both methods to the current daily timetable of the Korea Metropolitan Subway. We determined a feasible solution that results in an improvement of approximately 32% over the current timetable.