Calming the crisis of railway landslides

For two centuries rail has been a transport backbone moving goods and people. Rail routes have conquered challenging terrain by carving paths through rugged landscapes and building bridges where needed. This rail route legacy relies on extensive earthworks, cuttings, embankments, and slopes to maintain the shallow gradients needed for reliable operation.

What happens when these engineered slopes age? What happens when they slip, slide or fail?

At best, a railway landslide is a major service disruption; at worst, it's a disaster.

The Growing Rail Landslide Threat

Earth movements wreak havoc on tracks, leading to operational shutdowns that can last for days, weeks, or even months while stabilisation and material removal take place.

Almost universally we observe landslide events occurring with increased frequency with many predicting the rise to continue. Some attribute this to more frequent extreme weather events, some blame aging or neglected infrastructure and others point the finger of blame at climate change. In reality all are likely contributors to an increasing rise in reported rates of failure across many railways and railroads.

Recent railway landslides serve as stark reminders of this persistent threat:

• The Carmont Derailment in the UK highlighted how even a small amount of material in the wrong place can be catastrophic as gravel and debris washed onto the track, caused a fatal derailment.
• The 2024 Finneidfjord derailment in Norway claimed the drivers life and was one of 863 mudslides and rock falls on Norwegian railways over the previous decade.
• The Riedlingen derailment in Germany in 2025 bore many striking similarities to Carmont, killing 3 and injuring dozens more when a train struck debris washed onto the tracks by heavy rain.

The Danger Zone

The most dangerous period for railway landslides usually occurs after the slope fails, but before it is identified by operations teams. The risk of trains striking obstructed tracks at speed poses an existential risk to trains and the passengers, freight and staff they carry.

Traditionally many railways rely on visual inspections and train staff reports to spot unstable slopes, a process fraught with limitations especially when extreme weather events are a common trigger for failure to occur. When a driver sees a landslide across the route, it is often too late to stop before a collision with the debris or before the train travels over potentially displaced, compromised track.

It is therefore essential that landslides are identified as they occur, rather than as they are found by train crews.

The Limitations of Traditional Monitoring

Where slopes are known to be high-risk, trackside sensors can be deployed to monitor slope movements. However, to provide adequate detection resolution across a long slope you might need many many sensors, e.g., over 100 tilt sensors to monitor a 150m long cutting. Each sensor requires installation (into a potentially unstable slope), together with power, maintenance, and supporting communications infrastructure.

This high sensor count required makes protecting large lengths or entire rail routes impractical and prohibitively costly, limiting their application to shorter lengths of high-risk slopes or those that are known to be moving, leaving a significant proportion of the route unprotected. Other measurement options, like wire sensors, are prone to false alarms and need disruptive on-site resets, further limiting their widespread application.

Despite spending tens of millions of pounds on remote monitoring less than 10% of UK landslides were identified by remote sensors.