SIMULTANEOUS LOCOMOTIVE AND CAR ASSIGNMENT AT VIA RAIL CANADA

Given a periodic train schedule and a fleet composed of several types of equipment, the simultaneous locomotive and car assignment problem is to determine a set of minimum cost equipment cycles such that every train is assigned appropriate equipment and some side constraints are satisfied. The authors present a model and heurisitic solution approach based on mathematical optimization to solve the problem of assigning locomotives and cars to passenger trains. They first present a basic formulation that translates maintenance requirements and other fundamental difficulties of the problem. Next, they discuss several extensions, such as substitution possibilities and the minimization of switching operations, which are required in a real-life application. The resulting model is optimized through a branch-and-bound method in which the linear relaxations are solved by column generation. The model and solution strategy were tested on data from VIA Rail in Canada and a complete system based on this approach is now implemented ate the company