RAIB reports on Heathrow Express derailment

摘要

RAIB has issued its report into the derailment of an empty Heathrow Express Class 360/2 EMU at London Paddington at 05.20 on May 25 2014. The report concludes that the leading bogie of the third vehicle became derailed on a track defect which, according to Network Rail's standards, required repair within 36 h. It also concludes that the bogies on the TOS2 vehicle in the middle of the set had been set up incorrectly following tyre turning and that this had 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. RAIB found that the incorrect set-up was the result of the repeated implementation by Siemens technicians, responsible for maintenance of the fleet at Old Oak Common depot, 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 the anti-roll bar which resulted in them setting it in such a way as to create the wheel load imbalance.