07.02.18
Track boundary confusion between NR and LU caused Wimbledon derailment
Confusion over which body should be responsible for a section of track near Wimbledon station contributed to a derailment in November last year which forced 300 people to be evacuated.
Investigators from the RAIB said the problem came because a 24-year-old agreement between Network Rail (NR) and the London Underground (LU) setting out track boundaries was not clear.
The incident saw SWR’s 04.54 service between Basingstoke and London Waterloo derail shortly after leaving Wimbledon station early in the morning.
Travelling around 19mph, the train traversed a link line and the left-hand set of wheels fell from the rail head leaving them in the space between the two rails causing the opposing wheels to leave the track and drag across the ground.
The train continued in this state for more than 185 metres, causing significant track damage.
The track in question connects two other lines maintained separately by LU and NR, but the RAIB said the boundaries of each organisations responsibility were not clearly signed or represented on a diagram drawn up in 1994.
Initial lines of demarcation were agreed between LU and Railtrack, NR’s predecessor, but when investigators cross-examined the two organisation’s diagrams they found a gap, meaning a section of track was not always checked.
However, in the period in which the track was not properly maintained it had deteriorated, with the gauge spread increasing over time and leaving a potentially dangerous situation.
“The distance between the rails was greater than the permitted maximum,” the RAIB’s report explained. “The condition of the track suggested that it was poorly installed and that it had deteriorated over a period of many years, including an increasing distance between the rails.”
In addition to issues or signage and demarcation, patrollers from both NR and LU were unable to inspect the sections of train in question because of differences in personal track safety certifications between the two companies.
The RAIB report warns both infrastructure owners to deal with the issue, while also counselling other organisations responsible for track to take care with issues surrounding areas of maintenance.
Images: RAIB
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