epsilon-constraint method for dynamic multi-objective model of optimal fleet sizing and allocating wagons: a case study

In this paper, the modeling of determining the optimal number and allocation of freight wagons of an iranian railway company is presented in the form of a pure integer programming model. first, a dynamic single-objective model considering the owned wagons was presented. by using gams software, the model was solved and 35% of the demand was not met. then an innovative dynamic multi-objective model was proposed. to deal with this multi-objective model, ε-constraint method was used. the multi-objective model increased the profit compared to the single-objective model, and in addition, all demands were met. according to the results obtained from this model, the minimum number of wagons that the company must rent from other companies to meet all demands is 555 wagons.