Pacific National has been found to have failed to act upon recommendations from internal investigations of wheel fractures before a coal train derailment in August, 2015.
Pacific National recorded seven wheel fractures on coal wagons in NSW between May, 2013 and October, 2015, despite no record of any wheel failure in NSW in the previous six years.
The company failed to respond to an internal report in 2013 recommending earlier retirement of coal train wheels until the derailment of a fully laden coal train bound for Port Waratah from Maules Creek on August 28, 2015, an Australian Transport Safety Bureau (ATSB) report found.
“Despite a number of incidents Pacific National did not take adequate action, before the derailment, to reduce the risk of wheel defects, especially in light of previously identified contributors,” the ATSB found.
The failure of a bogie wheel with multiple fractures as it travelled through Pangela towards Port Waratah in August, 2015 came after a month of alerts indicating the likelihood of a fault.
No one was injured in the derailment that damaged 590 metres of train track and 963 sleepers.
Despite wheel impact load detectors showing increasing levels in the weeks before the incident, “no immediate action was taken to inspect the wheel before it eventually failed”, the ATSB report found.
An ATSB investigation after the incident found wheel inspection processes were not effective in detecting surface damage or cracks. The failed wheel was close to retirement and had a rim thickness less than a retirement level recommended in an internal report after wheel fracture incidents in 2013 at Metford and Greta.
“The failed wheel was approaching the end of its service life with a rim thickness of 25 mm. This low rim thickness increases propensity to thermal distortion and is likely a significant factor into the thermal crack formation and propagation that occurred,” the ATSB found.
Five of the seven wheel fracture incidents were detected at Pacific National’s rail maintenance facility at Greta. Only the Pangela incident resulted in a derailment.
Three incidents were reported before the August 2015 derailment, and three more were reported within a two-month period after the derailment.
“Following the first three wheel failures internal reports recommended changes to reduce the risk of wheel defects. Only limited action was taken by the operator prior to the derailment,” the ATSB found.
The first reported incident at Metford in May, 2013 involved a wheelset three weeks short of being removed from service. Pacific National said the incident was the first identified wheel failure since the installation of wheel condition monitoring in 1998.
The ATSB noted wheel fractures often occurred because of excessive loads on wheel treads associated with braking issues. Diminished wheel rim thickness increased risks and was a “likely contributory factor” in the wheel fractures.
A Pacific National spokesperson said the company had increased the minimum thickness of its coal fleet wheels from 25mm to 28mm and modified bogies to reduce the risk of thermal cracking.
“This involved thousands of wheels and the project was completed well before the regulator issued its recommendations,” the spokesperson said.
“This project means we have dramatically decreased the chances of this kind of incident from ever re-occurring.”