An Australian Transport Safety Bureau investigation into a derailment in Central Queensland has made a range of findings related to procedures during and after track disturbance maintenance works.
A transport safety investigation was launched after 20 empty coal wagons and two remote locomotives (mid-train) derailed near Mount Rainbow and Dumgree, resulting in substantial damage, but fortunately no injuries, on 30 October 2021.
“The investigation found the derailment likely occurred due to a track irregularity following ballast undercutting work completed two days prior,” ATSB Director Transport Safety Kerri Hughes said. “This irregularity likely developed during the passage of the train over that section of track.”
The ATSB found the rail stress-free temperature near the point of derailment was not adjusted following the track work, as planned.
“This is what is specified in the rail design as the temperature at which the rail is neither contracting nor expanding,” Ms Hughes explained.
“As the track near the point of derailment was not re-stressed (adjusted) after the track work, this left the track in a stressed condition when handed back for service.
“Additionally, a temporary speed restriction was not applied following works, as it should have been, further increasing risk.”
An additional factor increasing risk, identified by the investigation, was a lack of temporary track monuments being regularly placed throughout the worksite, during the track works.
“These temporary track monuments help reduce the risk of a track not being returned to the correct position following track disturbance work,” Ms Hughes noted.
Since the derailment, the track operator, Aurizon, has implemented various safety actions, including developing and implementing a rail stress worker course.
“This accident highlights the importance of assuring track stability following disturbance work, through having a correct rail stress-free temperature,” Ms Hughes explained.
“Likewise, track stability assurance also relies on the use of accurate track offsets, during, and temporary speed restrictions, following, track disturbance work.”
Read the report: Derailment of coal train 9QJ5, near Mt Rainbow, on the Moura Line, Queensland, on 30 October 2021