Direct rail services between Paris and Milan finally restarted after a 19 month suspension. Reopening on 31 March 2025, the route had been closed after prolonged heavy rains caused 15,000 cubic meters of debris to block the line near Maurienne in the French Alps.
This event reflects the growing impact ground instability is having on rail operations. Increasingly frequent incidents driven by extreme weather events and ageing infrastructure are resulting in operating restrictions, line closures, emergency repairs and, in the worst cases, accidents.
Such incidents are highly damaging to Operators’ KPIs, hitting all measures from capacity to customer satisfaction and safety. They are also costly with immediate impacts from lost revenue and repairs as well as medium-term impacts from investment in resilience measures. A scale of the costs can be gauged from two recent examples:
In November 2021, extreme rainfall in British Colombia, Canada, led to flooding and landslides that caused damage at 30 locations, with 20 resulting in significant loss of infrastructure including bridges and embankments. The same year, a landslide at Kestert in Germany cut one of Europe’s most heavily used freight traffic lines and a central part of the Rhine-Alpine transport corridor which took six weeks to reopen the first of its tracks.
The event in British Columbia affected local rail operations for 10 days, yet the estimated impact was CAN $25M on revenue alone. The costs for climate adaptation are even higher; Canadian Pacific Railway estimated the total cost to respond to and mitigate physical climate related risks and improve network resiliency at approximately CAN $1.048B (in 2023).
The problem of instability is not limited to mountainous regions. Over a third of the UK’s 33,000km rail network crosses areas where instability may be present or anticipated due to features such as old landslides, failure-susceptible geology, exposed coastal sections and aging embankments and cuttings.
Overlay the infrastructure (the UK rail network has ~190,000 embankments and cuttings, in addition to 70,000 structures) and the scale of the challenge Operators face becomes apparent. How do you gain visibility and understanding of the risks to identify emerging problems earlier and inform effective resilience investments?
Over a third of the UK’s 33,000km rail network crosses areas where instability may be present or anticipated.
Detecting problematic changes in movements requires regular, precise measurements. With thousands of kilometers and tens of thousands of assets, it is simply not possible to deploy instrumentation or conduct regular resurvey universally. Even mapping high risk locations is a problem and it is becoming harder as a climate change sees previously stable sites become active.
Thankfully, advances in satellite imaging and analysis mean it is now practical to provide precise monitoring at scale using synthetic aperture radar Synthetic Aperture Radar (SAR).
SAR is a type of radar that transmits signals toward the Earth and records the reflected signals. Using a technique called Interferometric SAR (InSAR), data collected over the same location can be compared to detect ground and structural movements with millimeter-level precision. This method provides high-density coverage, enabling rapid, large-scale monitoring without the need for on-site visits or sensor installations.
InSAR supplements existing methods for Rail networks, filling gaps in observation to reduce risks of costly failures. It can also establish efficient and effective layered monitoring using InSAR’s regular network-wide visibility of movements to:
- Identify high risk areas that are currently unmonitored as potential sites for investigation or in situ monitoring;
- Provide ongoing regular monitoring over the remaining majority of sections without installed sensors; and
- Enhance detection and interpretation of movements for sites with existing ground-based monitoring by increasing measurement density, extending coverage beyond the rail corridor boundary and creating decade-long movement histories.
Using regular InSAR monitoring, Rail Owners and Operators can build a more complete and reliable view of ground and structural instability. Identifying early signs of risk enables remedial action to be taken before situations escalate into disruptive and costly problems. It also provides important insights into the changing nature of hazards as landscapes and infrastructure respond to increasingly frequent extreme weather events.
Discover how easily CATALYST INSIGHTS Ground Displacement Monitoring can deploy and deliver regular precision measurements to enhance monitoring for specific sites to entire rail networks.
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