A main component of total cost, transportation costs depend on the empty freight car mileage and include, for example, energy costs and freight car wear costs. Transportation costs can be modeled as proportional to the number of moved cars and the transportation distances. Tactical planning impacts transportation costs through the design of the timetable, while the operational planning stage does so by changing the routes of the freight cars.
Transportation costs are of particular interest to the distribution of empty cars, since the origin-destination flows of empty cars are not given, but can be influenced during operational planning. We thus include a transportation cost that is proportional to the number of cars moved for each origin-destination pair, and the corresponding distance.