19 September 2012
The Australian Transport Safety Bureau (ATSB) has concluded that freak weather was to blame for the partial collapse of a rail bridge in December.
Rail company Genesee & Wyoming Australia (GWA) welcomed publication of the report into the freight train derailment at the Edith River bridge in the Northern Territory.
“While we appreciate that many people were affected by the accident, we are pleased that the report acknowledges the accident was clearly one created by a severe weather event and Genesee & Wyoming was not found to be at fault for the bridge’s collapse,” said GWA managing director Bert Easthope.
Isolated, torrential rains after Cyclone Grant increased the river’s depth from less than 4m when a GWA train crossed the bridge on 26 December to more than 11m when the next GWA train rounded the left-hand-curve approach seven hours later. The train reached the submerged bridge, causing it to partially collapse and derail the train as it attempted to stop.
The flood’s magnitude vastly exceeded the one-in-100-year event that the bridge was designed to withstand, and the ATSB report found that “in these circumstances it is not unreasonable to expect partial failure of the bridge structure or approaches.”
Operating under its Cyclone Response Plan, GWA had held back the two freight trains and inspected the rail line for flood damage prior to releasing the two trains. The ATSB report found that “there was no record of any previous flood event, since the construction of the Edith River Rail Bridge, at or near the site that would have heightened the alertness of GWA to the risk of a wash-away as occurred on 27 December 2011.”
The company had already been acting on certain recommendations identified in the report, including installing water-level-detection units on the six major bridges north of Katherine to alert train control and crews when water levels present a danger. GWA is also establishing closer relationships with a range of government agencies regarding the monitoring and reporting of extreme weather events and potential flooding. These new measures will be in place prior to the onset of the 2012/13 cyclone season.
“The report highlights one indisputable issue; any piece of infrastructure as extensive as the Adelaide to Darwin rail line cannot be risk-free. It traverses the length of Australia and some of the most exposed land in the country. We should take pride from the fact that we manage one of the longest rail lines in the world with remarkably limited interruptions,” said Easthope.
In August, GWA replaced two girders on the Edith River bridge that received temporary repairs following the derailment. Replacing the girders removed restrictions on the speed and axle loading of trains crossing the bridge since the flood.