Energy saving in railway timetabling: A bi-objective evolutionary approach for computing alternative running times

• Computing alternative train running times is tackled with a bi-objective evolutionary algorithm.
• Running time and energy consumption are optimized concurrently.
• Compromise solutions are produced to help train-practitioners for building train timetables.
• Speed profiles are built in function of the train optimal control theory.
• Results obtained on two lines are detailed and analyzed.

The timetabling step in railway planning is based on the estimation of the running times. Usually, they are estimated as the shortest running time increased of a short time supplement. Estimating the running time amounts to define the speed profile which indicates the speed that the train driver must hold at each position. The approach proposed in this paper produces a set of solutions optimizing both the running time and energy consumption. The approach is based on an original method of speed profiling performed by a multi-objective evolutionary algorithm. The speed profiles found by the evolutionary algorithm are all compromises between running time on the one hand and energy consumption on the other hand. A set of results obtained on two lines are analyzed and discussed to highlight the relevance of such an approach in a practical context.