The failure of a wagon axle due to fatigue cracking, which led a freight train to derail and for a second train to collide with one of its containers near Rockhampton, highlights the importance of systematic risk management, an ATSB final report explains.
On the evening of 29 January 2023, a Pacific National-operated freight train was approaching the town of Marmor, Queensland.
While travelling at about 100 km/h, an axle in the train’s sixth wagon fractured, and the rear 8 wagons of the train subsequently separated and derailed, piling up at the Bills Road level crossing.
The driver was initially unaware of the separation, but felt the train was not responding as expected, and then saw sparks in the locomotive mirrors, so applied braking.
The front section of the freight train remained on the tracks, and subsequently came to a stop about 1.3 km from the initial derailment location.
Around the same time, an Aurizon-operated coal train was travelling in the opposite direction on the adjacent track, when its driver saw the dust generated by the accident ahead, and applied emergency braking.
A short time later, the coal train passed the front section of the freight train, and its lead locomotive collided with a shipping container which was still attached to the front section of the freight train, but was fouling the track.
Fortunately, the coal train stopped before reaching the wreckage at Bills Road level crossing.
Both trains were substantially damaged in the accident, but each train’s crew was uninjured.
ATSB Chief Commissioner Angus Mitchell said the appearance of fracture surfaces on the failed axle was consistent with fatigue crack growth, followed by overstress fracture.
“The fatigue crack very likely initiated from impact damage to the axle surface at some time before the accident,” Mr Mitchell said.
“It was found the specific design of the fractured axle presented a greater risk of failing as a result of a damage-initiated fatigue crack than another axle design used by Pacific National.”
Since the accident, Pacific National has phased out all axles conforming to this design, which has a 154 mm diameter axle barrel.
“Importantly, the investigation found the operator’s risk controls before the accident did not provide the best opportunity to address axle damage capable of initiating a crack, or to ensure axles with growing cracks were removed from service.”
In addition, the operator did not ensure that the responsible work group within the organisation performed risk management activities in accordance with documented procedure, specifically regarding the use of risk registers and training.
This limited the group’s ability to systematically manage risks that fell within its scope.
Pacific National has subsequently taken several measures to address these issues, which are detailed in the final report.
“Systematic risk management, where risks are identified, assessed, eliminated, or controlled, is critical for rolling stock operators to remove safety risks as far as is reasonably practicable,” Mr Mitchell said.
The investigation report notes the national rail regulator expects operators to use risk registers to monitor and review identified risks and the adequacy of control measures, on an ongoing basis.
“Risk registers ensure that there is a mechanism promoting re-evaluation of a risk where controls have been implemented to ensure the controls are effective,” Mr Mitchell concluded.
Read the final report: Derailment of freight train 82P7 and subsequent collision with coal train 9F02, 3 km east of Marmor, Queensland, on 29 January 2023