Optimal Pacing of Trains in Freight Railroads: Model Formulation and Solution

Recent developments in location systems technology for railroads provide a train dispatcher with the capability to improve the operations of a rail line by pacing trains over a territory; i.e., to permit trains to travel at less than maximum velocity to minimize fuel consumption while maintaining a given level of performance. Traditional railroad dispatching models assume that the velocities of the trains moving over a dispatcher's territory are fixed at their maximum value and, thus, are incapable of dealing with a pacing situation. This paper presents a mathematical programming model for the pacing problem and describes alternative solution procedures for this model. Analytical and numerical evidence are presented that confirm the applicability of a heuristic solution procedure for this problem, as well as providing evidence that a pacing approach versus the traditional dispatching approach is an efficient and potentially cost effective method for the control of train movements.