RAIB investigation - Gloucester derailment

The RAIB is investigating the derailment of a freight train that happened at around 20:15 hrs on 15 October 2013, on the approach to Gloucester on the railway line from Newport via Lydney.

The train comprised a class 66 locomotive and 14 twin container flat wagons, loaded with curtain sided containers. It was travelling at a speed of around 69 mph (111 km/h) when the rear axle of the rear wagon derailed around 4 miles (6.5 km) from Gloucester. The maximum permitted speed for this section of railway line was 90 mph (145 km/h) although the maximum permitted speed for this train was 75 mph (121 km/h).

The train driver was unaware of the derailment and the train continued with one axle derailed for a distance of around 3.8 miles (6.1 km) until, at Gloucester West junction, the derailed wagon collided with a set of facing points while travelling at 22 mph (35 km/h). Here both wheelsets were torn from the rear bogie and the empty container on the rear wagon was thrown off. The driver was slowing the train to comply with line speed restrictions and remained unaware of the derailment.

The train then continued towards Gloucester causing further damage to the track and wagon, damaging two bridges and throwing some debris onto a road below. As the train arrived into Gloucester station, the driver brought the train to a stand after he received an emergency message from the signaller over the cab radio system, calling for all trains in the Gloucester area to stop. The signaller had become aware of the derailment through damage to the signalling system. No one was injured as a result of this accident.

Image of the derailed wagon outside Gloucester station
Image of the derailed wagon outside Gloucester station

Examination of the line on the approach to the point at which the rear axle derailed, revealed evenly spaced dips in the rails which resulted in regular variations in the vertical height of the track; a phenomenon known as cyclic top.

Image of the track on the approach to where the rear axle of the rear wagon derailed
Image of the track on the approach to where the rear axle of the rear wagon derailed

The RAIB’s investigation will seek to identify the sequence of events leading to the derailment. It will consider how the track was maintained and why the train was permitted to run at a high speed over a section of track with cyclic top. It will also consider the design of the wagon and why the container fell off the wagon.

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

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

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