Policies for Positioning Empty Containers in an Inland Multi-depot System

This research focuses on the problem of positioning empty containers in a port area with multiple depots. Three options are considered to prepare the required extent of positioning: positioning from other overseas ports, inland positioning between depots, and leasing. The policies for empty-container management are as follows: a coordinated (s, S) inventory policy for overseas positioning, (ri, Ri) policy at each depot for inland positioning; and a simple leasing policy with zero lead-time. For inland positioning policy, four different methods are proposed to reposition empty containers between depots. Customer demands and returning containers in depots and lead-time for positioning from overseas are considered as uncertain factors. The objective is to obtain the optimal policy in order to minimize the expected total cost including inventory holding, overseas positioning, inland positioning and leasing costs. Different optimal policies are obtained corresponding to different methods of inland positioning and they are then compared with those of non-inland-positioning (NIP) policy so as to prove the effectiveness of the proposed approach. A simulation-based genetic algorithm is developed to find the optimal policies. Numerical examples are given to demonstrate the results.