Mixed integer programming based maintenance scheduling for the Hunter Valley coal chain

Abstract

We consider the scheduling of the annual maintenance for the Hunter Valley Coal Chain. The coal chain is a system comprising load points, railway track and different types of terminal equipment, interacting in a complex way. A variety of maintenance tasks have to be performed on all parts of the infrastructure on a regular basis in order to assure the operation of the system as a whole. The main objective in the planning of these maintenance jobs is to maximize the total annual throughput. Based on a network flow model of the system, we propose a mixed integer programming formulation for this planning task. In order to deal with the resulting large scale model which cannot be solved directly by a general purpose solver, we propose two steps. The number of binary variables is reduced by choosing a representative subset of the variables of the original problem, and a rolling horizon approach enables the approximation of the long term (i.e. annual) problem by a sequence of shorter problems (for instance, monthly).