Scheduling optimisation for rail to ship dry bulk export stockyards

Large dry bulk stockyards provide a crucial interface between rail and sea transportation of high-volume export commodities such as coal and iron ore. Due to the high cost of demurrage for queuing vessels, in the order of AUD40,000 per day, there is a strong focus on receiving and loading ships as quickly as possible with minimal queuing delays. However, due to capacity limitations of rail systems, typically the unloading of trains is prioritised over loading ships which puts upward pressure on demurrage costs and negatively impacts the capacity of the out-loading systems. A key factor in the efficiency of stockyard operations is decision making for allocation of stockpiles and stacker-reclaimers to fulfil each train unloading or ship loading task. The sequencing of tasks on stacker-reclaimers influences the delays incurred waiting to reposition the machines from one task to the next. Allocation of stockpiles to specific tasks influences the delays incurred through conflicts between two or more parallel tasks requiring common machines and stockpiles, and the need to pre-empt ship loading tasks to serve higher priority train unloading tasks. For each task there are typically multiple combinations of machine and stockpile that can be used. This makes for a complex decision problem, particularly with the scheduling horizon extending out to several days.

QUT has been working with engineering consulting firm Aurecon to develop algorithms capable of finding near-optimal solutions to this complex scheduling problem. The ultimate aim of the project is to deploy the developed algorithms into one or more Australian bulk terminals to which Aurecon is a trusted partner for engineering and advisory services.