9th WCTR, D2 A STRATEGIC MODEL FOR FREIGHT OPERATIONS ON RAIL TRANSPORTATION SYSTEMS

In this work we present a new strategic model for freight rail transportation systems. The objective of the model is predicting equilibrium flows and level of services, given O-D transportation demands for a set of different products. Programmed rail services, corresponding to trains that run over the rail network with fix schedules are considered. The model proposed has the following distinctive characteristics: i) Railway services and their operational characteristics are explicitly considered. ii) The distribution of empty cars and its assignment over the rail network is treated simultaneously with the assignment of products to be transported, considering the operating costs over the network and the transportation priorities. iii) Different priorities are assigned to different types of cars to be moved depending on the products transported. iv) Capacity constraints are considered for the movement of different products, depending on the availability of the type of cars necessary and the demands of products competing for the use of the same cars. This constraint makes that some shipments must wait longer in the origin or transfer yard if not enough capacity exists. A mathematical formulation of the problem described is develope