Llangollen Canal in Shropshire: Making a Case for Continuous Deformation Monitoring
By
Suz Pathmanathan
Nature can be expensive.
The recent collapse of a canal embankment on the Llangollen Canal in Shropshire has left boats stranded, disrupted local economies, and is expected to cost several million pounds to repair. What has drawn particular attention is not only the scale of the failure, but the fact that the embankment, an earthwork more than 200 years old, had been inspected recently and was not considered a priority risk.
So what went wrong?
Speaking in this Guardian article , Dr Jamie Pringle, a forensic geoscienst at Keele University, said bedrock in the area contained large amounts of salt, “which of course is soluble... That part of the Llangollen canal has Triassic Wilkesley halite and mudstone, so soluble rock, hence why they initially thought collapse was due to a sinkhole, I think,” he said.
As the Canal and River Trust has emphasised, investigations are ongoing and there is no single, obvious cause. Early analysis has pointed to a combination of factors: prolonged wet weather, elevated water levels, seepage into historic earthworks, and complex ground conditions. Taken together, the incident highlights a persistent challenge in civil and geotechnical engineering:
Inspections capture condition at a moment in time, not how a structure behaves between those moments.
The limits of periodic reassurance
The industry knows well that inspection and maintenance remain fundamental to managing canals, embankments, and other earth structures. Visual inspections, condition assessments, and targeted investigations are essential tools, particularly across large asset portfolios.
However, by their nature, inspections are periodic. They provide reassurance at a specific point in time, but they offer limited insight into how an asset is responding to changing conditions between site visits. On ageing earthworks subject to seasonal saturation, fluctuating hydraulic loads, and long-term material degradation, subtle deformation can develop gradually and remain undetected until it reaches a critical threshold.
The Shropshire collapse is a reminder that even well-maintained assets can behave unpredictably and that the absence of visible distress does not always equate to stability.
From snapshots to a focus on behaviour over time
In response to these challenges, there is growing interest across the sector in complementing traditional inspection regimes with approaches that provide insight into structural and geotechnical behaviour over time.
Continuous deformation monitoring is one such approach. Rather than replacing inspections or surveys, it adds an additional layer of visibility: tracking movement trends, rates of change, and emerging anomalies that may not be apparent during periodic checks. This shift from snapshot assessments to behavioural understanding can be particularly valuable during periods of heightened risk, such as prolonged rainfall, changes in loading, or nearby construction activity.
In practical terms, it helps bridge the gap between “everything looked fine yesterday” and “how is it behaving today?”
A practical example: Hamburg Quayside
This approach is already being applied on complex assets where the consequences of unexpected movement are significant. On the Hamburg Quayside project, continuous deformation monitoring was used alongside conventional survey and inspection methods to observe structural behaviour throughout works on a live waterfront structure.
By tracking movement trends continuously, the project team gained a clearer understanding of how the asset was responding as works progressed. This additional context supported more informed decisions around sequencing, safety, and risk mitigation, not because inspections were inadequate, but because behaviour matters as much as condition.
What the Shropshire incident reminds us
Failures like the Shropshire canal breach remain rare, but they sit within a broader context: ageing infrastructure, increasing environmental stress, and limited resources for inspection and maintenance. As asset owners and engineers continue to assess risk across large portfolios of earthworks, it is becoming clear that maintenance alone may not always be sufficient, and that inspections in isolation have inherent limitations.
A combined approach, integrating periodic inspection with targeted continuous monitoring on higher-risk or more complex assets, offers a pragmatic way to improve understanding of asset behaviour and manage uncertainty more effectively.
As investigations continue, the lesson is not one of hindsight or blame. It is a reminder that understanding how structures behave over time can be just as important as assessing what they look like at a single moment and that earlier insight often creates more options.
Talk to the TotaLite team to understand more about how they've consistently lowered costs and ensured better outcomes across the UK and Europe.