RAIL chiefs have been issued with eight recommendations following an investigation into a train derailment in Audenshaw.
Nine fully-laden wagons of a freight locomotive carrying aggregate – weighing up to 100 tonnes each – came off the tracks close to properties on Thornley Rise and Sidmouth Street on September 6, 2024.
No-one was injured in the incident, which sparked a huge emergency services response after nearby residents told of a loud screeching sound.
All nine wagons were recovered in just six days, six by rail but three which were badly damaged via road the following month.
Now the Rail Accident Investigation Branch (RAIB) has found the failure of a number of screws, which was undetected, caused the track – installed in what is described as a ‘non-typical longitudinal bearer system (LBS)’ – to essentially give way.
Maintenance records confirmed at least three previous screw failures, including one before 2020, in the same location.
However, it found many were unavailable and the lack of proper reporting and recording allowed these issues to go unaddressed.
The investigation also found that those screws which had failed, or were failing before the passage of the train, had not been detected by Network Rail’s automated and manual inspection regimes, which were not capable of reliably detecting it.
In its report, the RAIB states: “The derailment occurred due to a loss of restraint of the track gauge between the rails.
“This caused the wagons’ wheels on the right-hand side to drop from the rail into this widening space.
“The spread of the track’s gauge was caused by the failure of a number of the screws securing the baseplates to the longitudinal wooden bearers.
“Subsequent metallurgical examinations showed that these screws had sustained fatigue damage before the arrival of the train.
“RAIB examinations of a section of the LBS recovered from site found that there had been previous screw failures at the same locations.
“Records of inspection and maintenance activities confirmed that there had been at least three previous failures, with one occasion known to have been before 2020, although many of the required records were not available.
“Vehicle dynamics analysis and fatigue calculations carried out by RAIB during this investigation showed that these screws were not expected to have an infinite fatigue life when installed in the configuration used on the bridge, even though the forces from trains on the track were below the maximum limits stated in Network Rail standards.
“The LBS was installed in 2007 and an increase in the volume of traffic over the bridge since 2015 had accelerated the rate of fatigue of the screws.
“The investigation also found that those screws which had failed, or were failing before the passage of the train, had not been detected by Network Rail’s inspection regime.
“It further found that the significance of previous screw failures had not been appreciated by those responsible for inspecting and maintaining the LBS at this bridge.
“There were two underlying factors. Network Rail did not have effective processes for managing LBS assets, in regard to their design assurance, installation, inspection and maintenance.
“RAIB also found that the track team in the maintenance unit responsible for the LBS at this bridge had neither recorded, nor reported, previous screw failures, and this had not been identified nor corrected by Network Rail’s assurance regime over a period of years.”
The derailment, which affected a 24-wagon train, saw the railway closed for about eight weeks and the footpath running underneath the bridge shut for much longer while work was done on the bridge.
Now Network Rail had been given a list of recommendations by RAIB, including improving its management of LBSs, its records of them and the reporting of component failures.
It was also told to improve the way two disciplines responsible for the track and structures assets communicate to better manage them.
And it was told to review the way in which it assesses the effects of changes in rail traffic on its LBS assets and to consider any subsequent necessary changes in design, inspection or maintenance activity.
Finally, RAIB said Network Rail should improve its own assurance processes for LBS assets to ensure staff are keeping accurate records of inspection and maintenance activities.