Optimal Strategies for Energy-Efficient Train Control

Over the past decade, the Scheduling and Control Group has conducted an extensive program of research into the theory and practice of energy-efficient train control. Two distinct systems have been developed for providing train drivers with advice on energy-efficient driving strategies. In normal operation, the Metromiser system for suburban railways is achieving fuel savings in excess of 13% and dramatic improvements in timekeeping. The more recently developed Cruisemiser is designed to provide driving advice for freight trains on long-haul journeys. The theoretical basis for the work is discussed and the results are illustrated with selected examples. The following specific problem is considered. A train travels from one station to the next along a track with non-constant gradient. The journey must be completed within a given time, and it is desirable to minimise fuel consumption. It is assumed that only certain discrete throttle settings are possible, and that each setting determines a constant rate of fuel supply. This assumption is based on the control mechanism of a typical diesel-electric locomotive. The formulation and solution of a well-posed control problem will be discussed. This paper will present some recent results and show how these results can be used to determine a strategy of optimal type on a track with continuously varying gradeint. A series of examples will be used to illustrate the effect of gradient on energy-efficient driving strategies.