The role of earthworks
Earthworks—such as embankments, cuttings, and retaining structures—are essential for maintaining stable and efficient infrastructure across transport networks. These structures support railways, roads, and other developments, ensuring safe passage through varying terrain and gradients.
However, many earthworks were constructed before modern engineering standards, often using locally available materials with minimal compaction or grading. Stability remains a key concern as these assets age and face increasing environmental and operational pressures.
Destabilising forces at work
Earthworks achieve a natural equilibrium over time, but several factors can disrupt their stability. Increased loading from heavy transport, frequent use, and climate change-driven weather extremes are accelerating deterioration.
Water is a primary destabilising factor. Aging or insufficient drainage systems struggle to manage modern rainfall patterns, leading to surface and internal erosion, washouts, and scour. Prolonged wet conditions elevate groundwater and pore pressure, weakening structural integrity and increasing the likelihood of failure.
Site characterisation & assessment
Modern assessment tools enhance earthwork management:
High-density lidar captures slope angles, crest heights, and vegetation data, enabling detection of movement over time.
Ground penetrating radar (GPR) identifies subsurface anomalies, such as voids from burrowing animals, internal erosion, shallow bedrock, and drainage issues.
These technologies allow infrastructure inspections to be conducted at operational speeds using vehicle-mounted systems, reducing the need for manual surveys.
Targeted techniques such as refraction seismics, multichannel analysis of surface waves (MASW) and electrical resistivity imaging (ERI) can assist with a more detailed geotechnical analysis of the construction and condition of an earthwork, providing insight into material stiffness, identification of inhomogeneities and distribution of groundwater.
Surveys can for part of planned audits or, as shown in the example, be in response to a catastrophic failure of part of the structure.
Continuous monitoring & identifying change
Advancements in remote monitoring technology have improved the ability to detect early signs of instability:
- Satellite-based InSAR tracks millimetric elevation changes, providing early warnings of structural movement.
- Ground-based methods such as Distributed Acoustic Sensing (DAS) and wireless tiltmeters offer real-time alerts for localized shifts.
- Electrical resistivity imaging (ERI) and remote moisture monitoring systems help assess subsurface water distribution, identifying potential risk zones.
Conclusion
Ageing earthworks face increasing threats from environmental changes and higher operational demands. Advanced monitoring and assessment technologies provide critical insights, helping asset managers ensure safety and long-term resilience. Proactive earthwork management is essential for maintaining stable and reliable infrastructure.
Stay tuned to our blog series on the benefits of railway asset condition mapping.