SIDING ROSTER OPTIMISATION: CASE STUDIES IN THE MACKAY REGION

We address the issue of optimising the allocation of harvesting groups to sidings for a whole harvest season, once a harvester roster has been produced. Mackay Sugar’s aims in optimising a siding roster were to show that harvesters had sufficient opportunity to access sidings without exceeding siding and branch line capacities and provide a better means for harvesting groups to manage their own day-to-day movements across sidings. The task is difficult and time-consuming manually, because of the need to consider all of these criteria simultaneously. To overcome this, we applied operations research techniques to develop a model to optimise the siding rosters, resulting in the ability to produce an optimal roster for the entire Mackay region within 30 minutes on a standard PC. The optimal siding roster was made available to all harvesting groups within the Mackay region for the 2002 harvest season. The roster was not prescriptive but it was used as the basis for resolving clashes of two or more harvester operators wishing to use the same siding on the same day. The model was also used to conduct scenario analysis that would lead to harvesting groups reducing their number of movements across sidings.