Brake failure has been blamed for the rollaway of an iron ore freight train that had to be deliberately derailed in Western Australia's north.
The nearly 3km-long runaway train hurtled along BHP's Newman to Port Hedland line for about 50 minutes on November 5, leaving behind the driver, who had stepped out to inspect one of its 268 wagons.
The locomotive was derailed by staff at a remote control centre more than 1500km away in Perth, who diverted it to Turner's Siding, about 120km south of the populated port.
Nobody was injured but about 1.5km of track was damaged.
WA Iron Ore asset president Edgar Basto said on Friday BHP had completed its preliminary internal investigation and initial findings showed the "emergency air brake for the entire train was not engaged as required".
"In addition, the electric braking system that initially stopped the train, automatically released after one hour while the driver was still outside," he said.
"Due to integration failure of the backup braking system, it was not able to deploy successfully."
