The QMS is designed to reduce vessel waiting queues, by rationing the amount of coal each producer can export through the terminal so the amount handled by the terminal better matches the amount that can be delivered by the coal chain.

When the QMS was given approval in 2005 it was proposed as a short-term measure to manage the vessel queue while investment and capacity expansions took place.

While the ACCC said it was satisfied that the system is likely to result in a net public benefit, by reducing demurrage costs, it also said it was concerned about the long-term implications.

“The ACCC is concerned that the continued operation of the QMS has the potential to impact upon investment in the coal chain, reduce incentives for industry to develop a long-term solution, and reduce the likelihood of competitive entry in above-rail haulage services,” said the competition watchdog.

“As such, there are significant doubts as to whether the QMS will deliver a net benefit beyond 2008."