The derailment of five freight train wagons highlights the importance of robust network rules that provide guidance for degraded condition operations, an ATSB investigation found.
During the 31 March 2019 incident, SCT Logistics freight train 7MB9 was exiting a refuge loop at Goulburn, New South Wales, when the five wagons derailed and obstructed both the Up and Down main lines.
Prior to the derailment, the driver of the train had been authorised to pass a signal at Stop, since the signal could not be cleared due to a track circuit fault. The fault had occurred the evening before, when another train passed through the refuge. At the time, the network controller and the on-call signal electrician had consulted on the problem, and agreed that trains could continue by passing the Stop signal.
A transport safety investigation into the incident, conducted on behalf of the Australian Transport Safety Bureau by NSW’s Office of Transport Safety Investigation (OTSI), found that the wagons had derailed due to a broken rail, which had likely broken under the previous train. The break, which had probably caused the signal to be stuck at Stop, had gone undetected.
Personnel need suitable guidance in assessing when it is safe to continue operating trains, and to judge under what conditions operations can continue safely.
Examination of the track identified that a crack had likely initiated from a lack of weld fusion at the foot of the rail in an aluminothermic junction weld. This defect area was located in a portion of rail not easily detectible through continuous ultrasonic testing and was not detected during routine maintenance.
“It is critical that areas of the rail that cannot be easily inspected during scheduled continuous ultrasonic testing are tested thoroughly at the time of welding to ensure that the weld is free from defects,” OTSI COO and Deputy Chief Investigator Kevin Kitchen said.
The investigation’s findings also noted other factors that increased risk in relation to this occurrence, in particular regarding the network rules in place by rail infrastructure manager ARTC.
“Network rules that permit degraded operations must be assessed to ensure that the application of these rules do not increase risk to an unacceptable level,” Mr Kitchen said.
“Personnel responsible for implementing these rules should have sufficient guidance to assess when it is safe to continue operating trains, or under what conditions operations can continue.”Last update 21 May 2020