It was deliberately derailed at a set of points, operated by a control centre, about 119km from Port Hedland.
Global miner BHP Billiton BHP.AX BLT.L expects its operations in western Australia to take around a week to recover after a almost 3-km long train loaded with iron ore enroute to the coast for export was forcibly derailed on Monday.
BHP was forced to derail a loaded iron ore train on Monday morning after it travelled 92km without a driver.
The 268-wagon train began its solo journey when the driver got down to carry out inspection, and was soon moving at up to 110 km per hour.
The ATSB said it expected to finish its investigation by the second quarter of 2019. No-one was injured in the incident.
The world's biggest mining company said that it was working to fix a stretch of track nearly a mile long that was damaged when the train was forcibly derailed after speeding 57 miles without a driver through the Australian outback early on Monday morning.
"We are working with the appropriate authorities to investigate the situation", a BHP spokeswoman said in a statement.
WA Premier Mark McGowan said he had not been briefed on what happened but it would have been very concerning for everyone involved.
"Usually, once the driver leaves the train, the brakes are on, there's procedures for that", Rail Safety Consulting Australia owner Phillip Barker told ABC.
There were no injuries in the derailment, but the train was extensively damaged.
Analysts think iron ore prices could see a short-term bump as a result of this derailment, according to the news service.
Australia is one of the world's major sources of iron ore.
The Rio Tinto company says it completed its first delivery of iron ore using an autonomous train in July.