A new mathematical model for heterogeneous rail freight car fleet sizing problem

In the field of freight transport, the railroads of developing countries confront with many profound difficulties such as prominent trend of market reduction and decrease of customer satisfaction. In order to prevent these issues, operators should develop better strategies for more effective utilization of freight cars which requires appropriate fleet size. There are important interactions between decisions on sizing a railcar fleet and utilizing that fleet. Because transportation vehicles are expensive capital items, procurement the fleet always has been a crucial challenge. In this paper, a new formulation model for heterogenous rail freight car fleet sizing in the presence of economic factors is proposed. The mathematical model is dynamic and multi-periodic and car demands and travel times are assumed deterministic. Cars distribution and different procurement strategy is also considered in this model. The paper includes numerical example which check the efficiency and validity of the model.