An optimization model to utilize regenerative braking energy in a railway network

In this paper, we study the railway timetabling problem to utilize regenerative braking energy produced by trains in a railway network. An electric train produces regenerative energy while braking, which is often lost in present technology. A positive overlapping time between braking and accelerating phases of a suitable train pair makes it possible to save electrical energy by transferring the regenerative energy of the braking train to the accelerating one. We propose a novel optimization model to determine a timetable that saves energy by maximizing the total overlapping time of all suitable train pairs. We apply our optimization model to different instances of a railway network for a time horizon spanning six hours. For each instance, our model finds an optimal or near-optimal timetable within an acceptable running time. We observe significant increase in the final overlapping time compared to the existing timetable for every instance, thus making it possible to save the associated electrical energy.