A Comprehensive Formulation For Railroad Blocking Problem

In rail transportation, there have been several attempts to determine the best routes for shipments (a number of cars with the same origin-destination) through the network. Shipments enter into several intermediate yards on their routes to separate and regroup shipments into new trains. Most of time, every entering into a yard includes excessive delay for shipments; therefore it is an ideal plan that each shipment has been transported by an exclusive train service. Mainly because of restriction on a number of running trains, this plan cannot be adapted in most cases. Finding the optimal route over the rail network with above and other common constraints would be handled by railroad blocking problem. From 1980 to the present, many mathematical programs have been proposed in this issue. In literature, however, there has not been any model with all realistic constraints. In this article, we give a brief literature review on railroad blocking problem. Afterwards, we present a comprehensive mixed integer programming formulation for this problem. Finally, we solve a test instance to show our model is in line with our expectation.