Great Western Coffee Shop

A strange platform for a Heathrow train?

Derailment at London Paddington station 25 May 2014

RAIB is investigating a derailment that occurred at London Paddington main line station, on Sunday 25 May 2014.

The train that derailed was an empty five car Class 360/2 passenger train (reporting number 5T08), manufactured by Siemens and operated by Heathrow Express. It was travelling from Old Oak Common to Paddington in preparation for entering passenger service.

At 05:20 hrs, both sets of wheels on the leading bogie of the third vehicle derailed to the left when the vehicle was about 150 metres from the buffer stops in platform 3 and travelling at between 12 and 14 mph (19.3 and 22.5 km/h).

The driver twice stopped the train after it derailed. On both occasions, unaware of what had happened, he restarted the train. As a consequence, the train ran nearly 100 metres in a derailed state and was finally stopped with the right side of the derailed bogie in a pit that was located between the rails, which lifted both wheels on the left side of the rear bogie off the rails. No one was injured.

Platform 3 remained closed for the remainder of the day.

(http://www.raib.gov.uk/cms_resources/Paddington.jpg)

RAIB^s investigation will examine the sequence of events leading up to the derailment and will seek to identify the causes. This will include consideration of the design, maintenance and condition of both the track and the derailed vehicle. The RAIB^s investigation is independent of any investigation by the safety authority (the Office of Railway Regulation).

RAIB^s investigation is independent of any investigation by the Office of Rail Regulation.

RAIB will publish its findings, including any recommendations to improve safety, at the conclusion of its investigation. These findings will be available on the RAIB website.

At around 05:20 hrs on Sunday 25 May 2014, 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 a track defect which, according to Network Rail^s standards, required a repair within 36 hours. No one was injured as a result of the derailment.

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 along platform 3 exacerbated this unloading and contributed to the derailment.

The investigation has found that the incorrect setup 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 such a way as to create the wheel load imbalance. None of the checks in the procedure identified the incorrect setup because these checks were not monitoring parameters likely to provide a clear indication of a 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.

As a result of this investigation, the RAIB has made four recommendations to Siemens and one to Network Rail. The recommendations to Siemens relate to the revision of the procedure used to set the vehicle ride heights, training materials and competence assessments to capture the function of anti-roll bars, their method of adjustment and the risks associated with incorrect setup. The recommendations also cover a review of other maintenance procedures and a review of the effectiveness of Siemens^ recently developed processes for transfer of design information into maintenance procedures.

The recommendation on Network Rail is to review its supervision and self-assurance arrangements to identify shortcomings which led to the non-compliances with a mandated standard going unnoticed.