On Friday 02 June 2006 a Northern Line tube train became derailed while entering the reversing siding at Archway station in north London. The rear bogie of the last car was derailed, and the car became wedged across the entrance to the siding tunnel. The only person on board, the train operator, was unhurt but damage was caused to the track and services suspended for the rest of the day.
The immediate cause of the derailment was a broken switch rail in the points leading to the reversing siding. A causal factor was a defect in the surface of the rail at the back end of the switch rail and the lack of a chamfer on this edge, which together created the conditions for a fatigue crack to develop. There were three contributory factors.
RAIB has made three recommendations as a result of its investigation. They cover:
- the design and continued use of bullhead switch rails;
- the track inspection system.
Response to recommendations:
- RAIB will periodically update the status of recommendations as reported to us by the relevant safety authority or public body.
- RAIB may add comment, particularly if we have concerns regarding these responses.