As pothole costs soar and climate pressures intensify, ground engineering experts warn that the real problem with the UK’s roads may lie beneath the surface.
The rising cost of pothole repairs across the UK is back in the spotlight – but the issue goes far deeper than surface defects. Addressing the underlying ground conditions rather than repeatedly repairing damaged surfaces – could help reduce long-term costs and improve the resilience of key transport routes.
Changing weather patterns and ground instability are now being recognised as major contributors to persistent road damage and the cycle of repeated repairs.
According to the RAC, patrols attended 6,575 pothole-related breakdowns between April and June 2025.
At the same time, the Asphalt Industry Alliance’s Annual Local Authority Road Maintenance (ALARM) survey (which Highways News reported on recently) suggests almost one sixth of local roads in England and Wales will need resurfacing within five years.
The ALARM 2026 report also points to a record £18.62 billion backlog of carriageway repairs – equivalent to 12 years of work – despite increased funding. While 51 per cent of the network is still considered to be in good structural condition, around 16 per cent, or more than 32,500 miles, has less than five years of structural life remaining.
The problem below the surface
Potholes are typically treated as surface failures, but infrastructure specialists say many recurring issues originate below ground. Climate change, combined with rising traffic levels, is contributing to a gradual movement in the subsoil. This often goes unnoticed until visible damage appears, by which point the underlying structure may already be compromised.
The result is a cycle of reactive maintenance, with roads failing repeatedly despite continued
repairs.
Local authorities are feeling the strain
The impact is already being seen at a local level. In Cambridgeshire, a recent report identified an £800m maintenance backlog, with a significant proportion linked to roads built on peat. Around 40 per cent of the county’s network sits on peatland, where soil expands and contracts with changes in moisture and temperature.
The county’s highways and transport committee has warned that repairing peat-affected roads alone could cost up to £500 million, as many require full reconstruction rather than surface treatment. In the past year, 11km of such roads have been repaired at a cost of £5.5 million. Neighbouring Lincolnshire has faced similar challenges following last year’s record-breaking summer. Drought conditions caused ground movement and an estimated £1-1.5 million of immediate damage, with longer-term costs potentially reaching £10 million.
Highways teams reported a “shrink-swell” effect in clay soils during the heatwave, accelerating deterioration across parts of the network.
The Met Office has since confirmed that the summer 2025 as the UK’s warmest on record – so the
issue of climatic impact on our roads is not going away.
A shift in approach
Against this backdrop, specialists argue that focusing solely on surface repairs is no longer sustainable. Instead, addressing the underlying ground conditions could reduce long-term costs and improve network resilience. Early ground assessment and targeted stabilisation can help tackle the root causes of subsidence, preventing repeat failures and extending asset life.
With more frequent cycles of heavy rainfall followed by prolonged dry periods expected, ground movement is likely to become an increasing challenge for the UK’s ageing road infrastructure.
Continued change in weather patterns
While much of the focus on climate change centres on flooding, the stability of the ground beneath our infrastructure is emerging as a quieter but equally significant threat.
The start of 2026 has already highlighted how quickly extreme weather can test the resilience of national assets. Three named storms – Goretti, Ingrid, and Chandra – brought heavy rainfall and flooding to large parts of the country. The resulting disruption, damage and flood alerts underline the growing vulnerability of infrastructure that is ageing and increasingly heavily loaded.
Latest figures from the Environment Agency show some regions experienced rainfall reaching 159 per cent of the long-term average (LTA) in January. Both the south-east and south-west recorded more than 150 per cent of the LTA, while England overall received 132 per cent.
When soils are saturated, subsidence and ground instability risks remain elevated – and may continue long after the rainfall stops.
Targeted solutions
Maintaining and renewing ageing infrastructure remains essential to ensure roads can withstand traffic demands while avoiding disruption and safety risks.
The challenge with road repairs is often the major interruption, but there are some alternatives to ground stabilisation which can rapidly target areas whilst minimising construction delays. For example, Mainmark’s Teretek® Resin Injection technology has been used by authorities in the UK and internationally, providing a targeted, non-disruptive method of addressing voids and weakground conditions without the need for excavation or full reconstruction.
The technique has been used to re-level subsided pavements and roadways to strengthen subgrade soils quickly and cost-effectively, targeted improvement of weak subgrade soils.
A new approach
With hotter, drier summers followed by intense rainfall and flooding, soils weaken and shift. Infrastructure built decades ago, often on foundations designed for different environmental and traffic conditions, is becoming more vulnerable as climate patterns evolve.
Addressing this challenge will require a shift in how infrastructure resilience is assessed and managed. Early-stage ground investigation, monitoring and targeted ground improvement are becoming essential components of asset management strategies. Identifying subsurface risks before they escalate can significantly reduce lifecycle costs while avoiding emergency repairs and unplanned closures.
Early ground assessment and targeted stabilisation could help tackle the root causes of subsidence, reducing the need for repeated interventions and improving reliability across the network. The UK’s infrastructure is entering a period where geotechnical resilience must sit alongside structural and climate resilience in planning decisions.
(Pictures: Mainmark)
