Investigation reveals how a runaway 10,000-tonne coal train was stopped

An interim report has revealed how a runaway Hunter coal train was finally stopped after it took off suddenly as crew members were attempting to fix a fault.

The Office of Transport Safety Investigations (OTSI) has released its Interim Factual Statement into the extraordinary operational failure, which took place on July 25, finding the train was stopped when it came to a hill.

The fully laden and unmanned Pacific National locomotive had travelled downhill before coming to a stop at Nundah Bank about 1am.

Initial reports suggested the incident was triggered after the locomotive's computer caused the train to stop when it detected a problem with the braking system.

Crew members were attempting to rectify the fault when the locomotive suddenly took off.

The runaway 10,000-tonne train reached speeds of up to 90kmh while the network operator issued an emergency warning to other trains in the area.

The interim OTSI report found the train had "runaway approximately 20 kilometres on the Up Main Northern rail line".

"The runaway train started at Newdell Junction reaching speeds up to 90kmh before rolling to a stop on the uphill grade near Camberwell Junction," the report stated.

The investigation is focusing on "locomotive and wagon specifications and braking systems ... along with data loggers and CCTV".

Investigators will also review "the actions of the train crew and organisational processes for responding to train brake faults".

Operating procedures and maintenance systems, audio recording systems and network incident response systems will also be examined.

Pacific National is cooperating with investigators.

"Safety is Pacific National's highest priority," the operator said in an earlier statement.

"We take this incident extremely seriously and are fully cooperating with the regulator and all relevant authorities to understand exactly what occurred and identify any actions required to prevent a recurrence."

OTSI said the final report would be provided to the minister for tabling in both Houses of the NSW Parliament in accordance with section 46D of the Passenger Transport Act 1990.

Transport advocates have called on Pacific National to introduce additional operational requirements, including ensuring that train crew members do not exit locomotives or trains in operational environments without another authorised person present and on board where practicable.

"Operators shouldn't have to rely on luck when it comes to the safe operation of heavy rail. Ensuring workers, in such a freight-heavy region as the Hunter, have appropriate support and backup when performing safety-critical duties should be a priority across the industry," Sylvia Duong, head of the North Sydney Transport Association Commission into the Newcastle region, said.