01.05.15
Network Rail and Siemens to blame for train derailment
A catalogue of failures by Network Rail and Siemens led to the derailment of a Class 360/2 at Paddington station last year, according to the RAIB.
Its findings say that the derailment was caused by a combination of a track defect, which Network Rail should have repaired within 36 hours of it being identified, and the incorrect set-up of the bogies of the vehicle that derailed by Siemens technicians.
The incident occurred at around 5:20am on Sunday 25 May, 2014, when the third vehicle of an empty five-car Class 360/2 passenger train manufactured by Siemens and operated by Heathrow Express derailed while it was running along platform 3 at London Paddington station.
All four wheels on the leading bogie of the third vehicle became derailed on the track defect.
RAIB say that the derailment occurred because the bogies of the third vehicle were incorrectly set up, which resulted in the left-hand wheels of the leading bogie being partially unloaded even when stationary. The track defect then exacerbated this unloading and contributed to the derailment.
The investigation found that the incorrect set-up was the result of the repeated implementation by Siemens technicians of a procedure aimed at setting the vehicle ride heights following tyre turning or bogie replacement.
This procedure did not clearly instruct the technicians on how to adjust one of the bogie components (the anti-roll bar) which resulted in the technicians setting it in a way that created the wheel load imbalance.
An underlying factor was the lack of effective transfer of design information about the role and importance of the anti-roll bars between the vehicle designers (Siemens Germany) and the vehicle maintainers (Siemens UK).
The track defect had been repeatedly identified by Network Rail’s measurements of track geometry for at least three years. However the required processes to remedy the defect were not followed and this was not picked up by Network Rail’s assurance process.
RAIB issued several recommendations to both Network Rail and Siemens as a result of the investigation. Siemens are asked to revise their faulty procedure and review other maintenance procedures.
The recommendation on Network Rail is to review its supervision and self-assurance arrangements to discover why no one noticed a mandated task, repairing the track fault, was not undertaken.
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