At about 0011 on 10 April 2014, SCT Logistics train 3MP9 derailed after travelling over track that had been undercut by floodwaters near a culvert at the 535.150 km mark between Tarcoola and Malbooma, South Australia. The floodwaters caused scouring of the track formation, compromising its capacity to support the train.
About 300 metres behind the lead locomotive, the first of 18 wagons derailed including eight that rolled onto their sides.
There were no injuries to the train crew however there was significant damage to the track, rolling stock and freight goods.
What the ATSB found
The ATSB determined that runoff from the heavy rain that had fallen in the catchment area adjacent to Malbooma on 9 April 2014 caused a flash flood event. The volume of floodwater exceeded the capacity of a double drainage culvert designed for a 1:50 year average flood recurrence interval. This resulted in water overtopping the track formation with ballast and sub-grade scouring on the south side of the track.
The magnitude of the scouring meant that the track could not support the weight of train 3MP9 as it passed over the affected areas. The resulting deformation in the alignment of the track initiated the derailment.
From a risk control perspective, the ATSB found that the Australian Rail Track Corporation’s (ARTC) processes were ineffective in developing and implementing changes to operational procedures from the findings of previous incident investigations. The ARTC did not have a comprehensive system in place to identify and actively manage the risks to their network from severe weather events, and had not established a register for recording ‘special locations’ for the management of track infrastructure prone to flooding.
There were no anomalies found with the operation of the train or the condition of rolling stock before the derailment.
What's been done as a result
The ARTC has implemented Operational Procedure OPP-01-05 ‘Monitoring and Responding to Extreme Weather Events in the East-West Corridor’ and has purchased and installed remote weather monitoring and recording stations at Barton, Cook, Rawlinna and Zanthus. The weather station data will be linked to the Early Warning Network to provide automated alerts. Four water flow monitors have been installed at culverts identified through a hydrology study of the Trans Australia Railway. Field evaluation of this equipment is being undertaken.
Upgrades of the ARTC’s electronic asset management system are underway to optimise inspection and maintenance activities, including recording of ‘special locations’ affected by severe weather events.
To ensure that the safety of rail operations is not compromised during severe weather events, it is essential that rail transport operators have robust and responsive systems in place to actively monitor and manage the foreseeable risks.