NR earthworks maintenance measures “not effective”
A Rail Accident Investigation Branch report has concluded that the poor condition of an earth embankment and a lack of communication within Network
Rail contributed to the derailment of a single DB Cargo wagon at Willesden High Level Junction on May 6 2019.
At around 2130, a single wagon in a freight train derailed on a curve approaching the junction, and then rerailed as it passed over the junction.
Although no one was injured, RAIB stated: “A derailment like this has the potential to foul lines that are open to passenger traffic or strike structures.”
The investigation found that the track was supported by an earth embankment that Network
Rail had been monitoring since October 2016, and which was showing signs of progressive seasonal movement.
It said the derailment occurred because the wagon “encountered a significant track twist and had an uneven wheel load distribution”.
The RAIB report added that the measures NR had in place for inspection maintenance and mitigation were “not effective” in detecting the risk and protecting the safe running of trains.
Within NR, there are separate teams which are responsible for track maintenance and earthwork management. RAIB said it “identified the lack of sharing of information between these teams as a possible underlying factor” behind the derailment.
Three recommendations have been made to NR, concerning the use (and limitations) of information from its track geometry measurement trains for understanding the condition of the track and problems with the track bed and/or supporting earthwork structures, and how this may affect the safe running of train, along with measures to mitigate the risks arising from known defects in supporting earthwork structures.
Additionally, RAIB has identified learning points concerned with indications of poor track bed condition, the importance of good liaison between track maintenance and earthwork management teams, and the management of wagon diagonal wheel load imbalance as a result of the incident.