In rail network operations, discussions on how to navigate monitoring challenges frequently focus on questions of investment. CATALYST can lift the burden of monitoring challenges for rail operators.
New Civil Engineer magazine highlighted that only 9% of landslips on Network Rail's infrastructure were detected by remote sensors, despite a £33M investment in monitoring technology. While this statistic might appear concerning at first glance, it highlights gaps in current geohazard detection capabilities rather than mismanaged investment.
The NCE article reveals that of the 147 landslips identified across the rail network in 2023, only 13 were detected via remote sensors. The majority were spotted by maintenance staff, train drivers and earthworks engineers during routine operations. This statistic doesn't represent a failure of technology (more a misunderstanding of the function of in situ monitors) but it does highlight a critical blind spot in current monitoring methods – how to systematically identify areas of unrecorded instability and newly emerging risks.
The challenge is primarily a question of scale and economics. Consider the UK, with tens of thousands of kilometres of corridor and 191,000 earthwork assets under management, it's simply not feasible to install sensors everywhere. In situ sensors, like tiltmeters, are designed to monitor subtle changes in rates of movement at sites known to be unstable, not to scan entire networks to discover pre-existing or emerging areas of instability.
"With climate change increasing conditions that trigger instability, Rail Operators across the globe need monitoring strategies that match the scale of their infrastructure."
Approaching the problem using geographic information systems (GIS) to overlay geophysical properties (such as slope, soil type and geology) can provide indications of susceptibility to instability over wide areas, but these qualitative assessments do not quantify actual risk. The conditions that trigger geotechnical failures are also highly localized, so the spatial resolution of these studies is too coarse to direct targeted investment in site investigations or instrumentation.
This is where satellite-based InSAR (Interferometric Synthetic Aperture Radar) monitoring offers a transformative solution. InSAR addresses the fundamental gap in current risk assessment and monitoring methodologies by affordably delivering precise measurements at regional scale to bridge between susceptibility studies and in situ monitoring.
InSAR monitoring can identify millimetre-level ground and structural movements before they become visible to the human eye, allowing for early detection and remediation of areas before failures occur. Uniquely, it can also provide historical analysis of movement that gives engineers critical context for understanding the significance of current movements, seasonal patterns, slow-developing changes or deviations from trends that would otherwise go unnoticed.
Additionally, InSAR coverage is not restricted by access considerations - a crucial capability given many geohazards originate beyond the immediate rail corridor and a challenge well understood with CATALYST InSAR monitoring solutions.
In the example from Canada below, the analysis identifies problematic changes in movement between two points adjacent to the corridor and highlights the appearance of a potential hazard on the hillside above.
CATALYST solutions complement existing monitoring practices, serving as the "first line of detection," to identify undocumented and emerging risks across the entire network. The analysis enables Rail Operators to direct site investigation and in situ monitoring resources to specific locations where they're most needed and have on-going InSAR monitoring cover the much wider remaining areas.
Simply, current methods are like having spotlights on known problem areas, while large portions of the network remain in darkness. InSAR turns on the lights everywhere, revealing risks that would otherwise remain hidden until they cause visible damage and disruption.
The statistic highlighted in the NCE article doesn't represent a failure of strategy or technology but rather demonstrates the need for a more comprehensive monitoring strategy. You can't manage what you can't see, and current methods leave significant visibility gaps.
With climate change increasing conditions that trigger instability, Rail Operators across the globe need monitoring strategies that match the scale of their infrastructure. In its Climate Ready Plan, Scotland’s Railway states the need to “Move away from qualitative assessments of risk toward quantified risk assessments where possible and of value – drawing in the best available climate and asset data.”
CATALYST's InSAR monitoring service offers that capability – delivering regular precise measurement at scale that helps:
- spot potential risks before they impact safety and services;
- understand changing risk to inform climate resilience and adaptation measures
- validate models and refine desktop studies.
Combining the strengths of targeted in situ monitoring, extensive InSAR monitoring, susceptibility studies and inspections will equip Rail Operators with a comprehensive data-driven approach to geohazard management - one that is alert to change across the network, not just the areas already known to be problematic.
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