Stowage planning in the maritime container transportation to reduce the number of shifts

Abstract

In this thesis, we consider the stowage planning problem of arranging containers on board the containership in the maritime transportation system. In the stowage planning, it is important to minimize handling costs and the containership operation costs as well as to maintain the stability of ships. Since containers are accessible only from the top of the stack, undesirable additional handling such as shifting (temporary unloading and reloading of containers) is unavoidable if containers are stored on the container required to be unloaded at the current port. The main objective of stowage planning is to minimize the number of shifting for a tour of a containership. We decompose the stowage planning problem into two subproblems, assignment of container groups into decks and determination of loading patterns of containers in decks. For the first subproblem, we formulate a mathematical model to minimize the number of shifting and the crane movement time in ports, and suggest a greedy algorithm based on the primal network algorithm to solve the fixed charge transportation problem. For the second subproblem, we suggest a tree search method. To see the performance of the suggested algorithm, computation experiments are carried out on randomly generated problems based on real situation of an ocean container liner in Korea. Results showed that the suggested algorithm gave good solutions compared wit the solution of simplified model of Botter and Brinati solved by CPLEX 4.0, a commercial package to solve mixed integer programs.