RECOGNISING cracking in axles is fundamental to rail safety, the Australian Transport Safety Bureau says.
The Bureau has finished investigating a September 2017 incident near Kimburra in North Queensland, west of Charters Towers, where a wagon from an acid train derailed.
The train was carrying about 1.67m litres of sulphuric acid in freight tanker wagons and the crew initially failed to notice the derailment as it had little effect on the train’s performance.
After seeing sparks from the derailed wagon, the driver braked, the train stopping about 2km from the derailment point. There were no injuries nor sulphuric acid spill.
The train was repaired and the rail line reopened the following afternoon.
Then in August last year, a second derailment involving the same type of train occurred, with the ATSB analysing evidence from the second derailment as part of the investigation.
Both derailments were found to be from axle failure.
The ATSB also identified a fatigue crack existed and was of a detectable size at the time of the previous routine axle inspection.
However, anomalies in the inspection procedures likely led to the crack not being identified.
“Axles with undetected fatigue cracks that propagate to failure will usually result in a derailment,” the Bureau stated.
“Recognising that axles should be resilient to fatigue cracking from in-service damage, effective axle inspection techniques that detect cracking prior to failure are fundamental to rail safety.”