Before dawn on Monday 22 January 2018, a passenger train travelling between Mallaig and Fort William in north-west Scotland struck a large landslip on a remote section of line near Glenfinnan. The leading coach of the 2-car train derailed to the left and came to a halt embedded in landslip debris. There were no injuries, but some diesel fuel escaped from the damaged train and was carried by flowing water into a lineside drainage channel. Due to the inaccessibility of the site, pollution control measures were not put in place until later the following day, and by this time some diesel fuel had entered nearby Loch Eilt.
The landslip originated from a natural hillside above the railway and was triggered by a combination of rainfall and snow melting during a rapid thaw. The ground may have been saturated before it froze. A protective fence, which had previously been installed near the railway to trap falling rocks was overwhelmed by the event.
The RAIB found that Network Rail’s processes for managing landslip risk did not take account of the hazard caused by rapidly melting snow. It is unlikely that a greater understanding of snowmelt risk would have avoided the accident at Loch Eilt, but it could avoid or mitigate an accident in other circumstances.
The RAIB has made one recommendation to Network Rail to promote the development of weather forecasting processes to take account of risk due to snowmelt and ground thaw. The RAIB has also made one learning point concerning the importance of having effective and verified arrangements in place for responding to environmental emergencies in remote and inaccessible areas.