At about 0834 on 10 August 2013, freight train 9101 derailed at a failed mechanical rail joint between Tempy and Bronzewing in Victoria. Nine wagons located mid-consist derailed and separated from the consist with three wagons ending on their side. The two locomotives and the leading 21 wagons and the last 10 wagons remained on the track. Approximately 300 m of track was destroyed as a result of the derailment. There were no injuries to train crew in the incident.
What the ATSB found
The ATSB found that the mechanical rail joint failed due to the development of fatigue cracks in both fishplates resulting in their subsequent overload fracture. The fatigue cracks had originated in the top surface of each fishplate and it is possible that differential sleeper support may have contributed to higher than normal cyclic tensile stress in the fishplates. Lower than required fishbolt torque was also identified and it is possible that movement within the joint may also have contributed to the development of the fatigue cracks, and the subsequent joint failure.
The fatigue cracks had developed over a period of time and the overload fractures had occurred prior to train 9101. Movement of the separated rail ends during the passage of train 9101 resulted in a lateral discontinuity in the running rail at the joint and the train’s derailment.
The ATSB found that the degraded and deteriorating condition of the rail joint was not detected by track inspections. In the 27 months preceding the derailment, visual inspections of this section of track had been conducted solely from rail vehicles and track walking inspections had not been conducted at intervals specified by maintenance procedures.
What's been done as a result
V/Line has updated its maintenance system to generate automated work orders for track walking inspections. In order to improve the detection of track defects, maintenance staff have been provided with specific inspection criteria for track infrastructure including joints and fastenings in their work orders.
The implementation of effective inspection and maintenance regimes for the early detection and management of track defects is critical to the safety of rail operations.