Formulation and solution of a multi-commodity, multi-modal network flow model for disaster relief operations

This paper presents a formulation and two solution methods for a very complex logistical problem in disaster relief management. The problem to be addressed is a large-scale multicommodity, multi-modal network flow problem with time windows. Due to the nature of this problem, the size of the optimization model which results from its formulation grows extremely rapidly as the number of modes and/or commodities increase. The formulation of the problem is based on the concept of a time-space network. Two heuristic algorithms are proposed. One is a heuristic which exploits an inherent network structure of the problem with a set of side constraints and the other is an interactive fix-and-run heuristic. The findings of the model implementation are also presented using artificially generated data sets. The performance of the solution methods are examined over a range of small and large problems.