Rotted timbers caused Wanstead Park freight train derailment
Degraded longitudinal timbers on a bridge caused a freight train to derail at Wanstead Park on January 23 2020, according to the Rail Accident Investigation Branch’s report into the incident.
The 0531 Barking EurohubCalvert, operated by DB Cargo, derailed when the track spread on a bridge between Woodgrange Park and Wanstead Park in north east London, on the Gospel OakBarking line.
Two adjacent wheelsets from different wagons in the rear half of the train derailed when the track spread. One re-railed itself after travelling for a short distance, but the other remained derailed as the train continued for two and a half miles before stopping, causing significant track damage.
Track supported on longitudinal timbers is subject to special inspection by staff who have received extra training in the role.
The RAIB report, published on November 16, revealed that the state of the timbers was concealed by their superficially good exterior condition. It found that the inspection method and tools used by NR were not sufficient to detect the timber’s poor internal condition.
NR-operated track recording vehicles identified widening of the track gauge six times between March 2019 and January 2020.
On three of those occasions, maintenance staff responded but carried out work nearby due to erroneous GPS data. On the other three occasions, the track recording vehicles’ software did not report the location of the fault, so maintenance staff remained unaware of it.
Examination of the first wagon to derail and its maintenance records indicated it had experienced unusually rapid wheel wear over several years. RAIB says it is possible this meant it was imposing higher than normal lateral forces on the track (related to a defect which affected the way the bogie was able to rotate), sufficient to force the rails apart and cause the wagon to derail.
One recommendation was made to NR regarding improvements in the provision of track recording vehicle data to track maintenance staff, and another to wagon owner VTG Rail UK concerning the monitoring of maintenance activities to reduce the risk of defective rail vehicles entering service.