Empty Wagon Distribution Optimization

Empty wagon redistribution is one important link in railway freight transportation.An optimized empty railcar redistribution schedule is crucial to transportation production efficiency,especially in the situation where shortages of empty wagons occur,which is common in many third world countries.This paper introduces a mixed linear integer programming model aiming to optimize the empty wagon distribution schedule under the situation of wagon shortage.A network model is constructed to reflect empty wagon flows among origin and destination yards,with the optimization pursued through the minimization function of comprehensive distribution cost on one hand,and with the balance ensured by penalties imposed on unmet demands on the other hand.The model is then simplified for ease of solving thus the simplex method can be used in real circumstances.A case study of Zambia Railways is also done to test the model that has been developed for the problem being investigated.The results for this case study indicate that proper empty wagon redistribution can result in saved costs for the railway operator as well as improving the availability of empty wagons throughout the railway network of Zambia Railways Limited.