DIEM, Sez. Matematica Finanziaria, Facoltà di Economia Università di Genova, Via Vivaldi 5, Italy. E-mail: sciomach@economia.unige.it

Abstract

In this paper we analyse the impact of the yard organisation on container stowing operations. We deal with the Master Bay Plan problem (MBPP), that consists in stowing containers of different types into available locations on a containership; the aim is to minimise the berthing time in such a way that structural and operational constraints, related to both the containers and the ship, are satisfied. In particular, we study how the total stowage time changes due to possible reloading operations, when different picking sequences are considered. We use a binary linear programming model for MBPP that has been recently proposed in literature considering two main scenarios. First, we assume to have all containers ready to be loaded on board in the quay independently of their stack position in the yard. In this case, we solve MBPP as it is having as objective function just the minimisation of the loading time. Then, we take into account the yard constraints following the directions of the planning office, which makes the bay plans according to the stocking area requirements and the picking list for the containers to be loaded. In the third case, we present a procedure that enables us to consider different lot arrivals and opportunely relax some constraints. Moreover, we assume that the containers are stored in the yard into different stacks on the basis of their size, destination and weight, depending on the storage strategy chosen by the yard managers. We evaluate alternative yard storage strategies with real size stowage plans of a containership located at a maritime terminal in Genoa. The results show that, when we look for the berthing time minimisation, it is quite important to think about the optimisation of the flow of containers from the yard to the quay.