Overview
- The RAIB report, published on December 24, 2025, concludes the 2024 derailment was triggered by loss of track gauge restraint when baseplate screws on a longitudinal bearer system failed.
- Metallurgical analysis found the screws had already suffered fatigue damage, with evidence of at least three prior screw failures at the same locations and many required records missing.
- Investigators say neither automated nor manual inspections, including routine dynamic geometry checks, were capable of reliably detecting the screw failures before the accident.
- The bridge used an LBS installed in 2007, and RAIB analysis indicates increased traffic since 2015 accelerated screw fatigue beyond an infinite-life assumption for the configuration used.
- RAIB made eight recommendations to improve component assurance, LBS management, staff competence, cross-discipline interfaces, traffic-effect assessments, asset records and assurance, which Network Rail has accepted alongside completed repairs and enhanced maintenance regimes.