Network models for the expansion of grain storage facilities

Abstract

This study was undertaken for a number of grain co-operatives from a certain region in South Africa. A previous study done for these co-operatives indicated that existing storage facilities should be extended to accommodate increased production in the region. The proposed extension plan recommended the phased construction of extensions to silos in the region. These extensions should have a predetermined total storage capacity. The questions that remained were: How many silos should be extended, which silos should be extended and what should the capacity of each extension be? The objective is to minimise the sum of construction costs and the total cost of transportation between farmers and silos. A linear mixed integer programming model can be used to solve this problem. However, given the computational facilities at the disposal of the researchers, it was decided to rather use a heuristic procedure based on a transshipment model. These network models, their solution and the recommendations made on the strength of those solutions will be discussed.