A freight train derailment in Audenshaw, Greater Manchester, was caused by undetected failures in a specialist bridge track system, Britain’s Rail Accident Investigation Branch said in a report published today.
The report cites two underlying causes: Network Rail’s ineffective processes for managing longitudinal bearer assets across design, installation, inspection, and maintenance, and the local track team’s failure to record or report earlier screw failures that were not corrected by assurance checks.
RAIB issued eight recommendations to Network Rail, calling for stronger component assurance, clearer management guidance, improved staff competence, better coordination between track and structures teams, assessment of supporting structure condition, reviews of traffic impacts on fatigue, comprehensive national records of longitudinal bearer assets, and tighter assurance to ensure accurate maintenance documentation.
The train derailed at about 11:25 a.m. on Sept. 6, 2024, as it crossed a bridge over a public footpath, sending nine of 24 fully loaded wagons off the rails and heavily damaging the track, bridge and several wagons. No injuries were reported, but the route was shut for about eight weeks for repairs.
Investigators traced the derailment to a loss of gauge restraint — the widening of the distance between the rails — after multiple screws that secure rail baseplates to longitudinal wooden bearers on the bridge failed from fatigue. The bridge used a longitudinal bearer system installed in 2007, in which rails are fastened to timbers rather than conventional sleepers and ballast.
Metallurgical tests showed several screws had cracked before the train arrived, and records indicated at least three prior screw failures at the same locations, including one before 2020, although many required records were missing.
RAIB’s vehicle dynamics analysis found the screws were not expected to have an infinite fatigue life in the configuration used, even though train forces were below Network Rail limits.
An increase in traffic since 2015 likely accelerated fatigue. Automated and manual inspections did not reliably detect failing screws, regular geometry measurements remained within standard limits, and maintenance staff did not recognize the significance of earlier screw failures.
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