Modelling of empty containers repositioning problem

This paper deals with the problem of positioning empty containers in a region including a port with multiple overseas ports and inland depots. A shipping line is required to satisfy demand of empty containers from both regional customers and foreign branches of the same company. Demand and returning containers from both customers and overseas ports per period of time are assumed to be serially-correlated and dependent random variables. We addressed completely integrated models that include both transportation and inventory control for repositioning empty containers. First, a mathematical model is established for current operations including four network elements which are overseas ports, a regional port, local depots and customers. Improved models are proposed to overcome some limitations at each connection link: overseas-port, port-depots, and depots-customers, respectively. New empty containers moving policy among depots are updated. The objective is to minimise total relevant costs over planning horizon, including inland and overseas transportation costs, order cost, inventory costs and lost-sales. A real case study of Vietnam shipping line is investigated to analyse the performance of the improved models over the current model in different aspects.