Container Pre-marshalling Problem Minimizing CV@R under Uncertainty of Ship Arrival Times

Abstract

This paper is concerned with the container pre-marshalling problem which involves relocating containers in the storage area so that they can be efficiently loaded onto ships without reshuffles. In reality however ship arrival times are affected by various external factors which can cause the order of container retrieval to be different from the initial plan. To represent such uncertainty we generate multiple scenarios from a multivariate probability distribution of ship arrival times. We derive a mixed-integer linear optimization model to find an optimal container layout such that the conditional value-at-risk is minimized for the number of misplaced containers responsible for reshuffles. Moreover, we devise an exact algorithm based on the cutting-plane method to handle large-scale problems. Numerical experiments using synthetic datasets demonstrate that our method can produce high-quality container layouts compared with the conventional robust optimization model. Additionally our algorithm can speed up computations for solving large-scale problems.