Spotlight on derailment
RAINFALL and insufficient drainage have been pointed to as the primary causes that led to a dramatic train derailment near a drainage culvert southwest of Townsville.
The derailment, which occurred on the Mount Isa line near Charters Towers, saw 11 wagons of a loaded Aurizon freight train derail as it travelled through the area early on December 30, 2020 towards Townsville Jetty.
No crew were injured during the crash, and the locomotive itself stayed on track, however damage to the track and surrounds and the stock being transported were ‘substantial’.
The Australian Transport Safety Bureau’s investigation findings align with initial reports of the scene that indicated a ‘washout’ of the tracks was responsible for the conditions that caused the derailment.
ATSB Director Transport Safety Dr Stuart Godley said a series of rainfall events in the days prior had contributed to the crash.
“While the rainfall was heavy, the ATSB’S calculations did not indicate it exceeded the design flow of the culvert itself,” Dr Godley said.
“It is therefore likely the pipe’s throughput was restricted.” The culvert itself had been cleaned and cleared earlier in the month on December 6, suggesting other factors had played a hand in limiting the pipework.
“The throughput restriction could have been due to sinking, debris blocking the pipe, collapse of the pipe itself due to an exceedence of its service life – or a combination of the three,” Dr Godley said.
The investigation found that pooled rainwater on the upstream side of the culvert led to the track being undermined by the water, weakening it by the time the train travelled through the next morning.
“To minimise the risk of system inundation and track overtopping, rail infrastructure managers should ensure their drainage systems are fit for purpose, and are clear, open, and in a serviceable condition,” Dr Godley said.
According to the report prepared by the ATSB, the driver of the train noticed debris across the track, but was unable to stop the train in time. The weight of the lead locomotive then ‘lurched and dipped’ as it travelled through the washed out area.
The track, owned by Queensland Rail, has since undergone drainage improvements, with the 1,050mm pipe replaced by three new 900mm pipes. They have also hired a contractor to conduct a hydrology study along the rail line.