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.
The train, comprising four locomotives and 268 wagons, travelled 92km before being deliberately derailed at a set of points operated by BHP's Integrated Remote Operations Centre, around 119km from Port Hedland.
The miner suspended all of its rail operations on Monday after it derailed the iron ore train, damaging 1.5 kilometres of track and crushing numerous 268 fully-laden wagons in the process. No-one was injured in the incident.
The ATSB said it expected to finish its investigation by the second quarter of 2019.
'We are working with the appropriate authorities to investigate the situation, ' a BHP spokesperson said.
"Obviously it would have been very concerning for everyone involved - BHP and the workforce, and the people of Port Hedland - that a train was traveling down the track without a driver and obviously out of control", McGowan said.
There was no indication of what had caused the train to move without its driver.
With the capesize market already plagued by lacklustre Chinese demand for coal and iron ore, the BHP outage has depressed the sentiment further, according to Banchero Costa's head of research Ralph Leszczynski.
Despite that, BHP have said there is enough iron ore stockpiles Port Hedland for their operations to continue around Western Australia.
In July rival mining giant Rio Tinto clocked up a world first when its maiden driverless train voyage carried 28,000 tonnes of iron ore 280 kilometres from its Mount Tom Price mine to a WA port.