The challenge: breaking the cycle of repeat repair 

Across the UK network, many defects are not isolated failures. They are symptoms of deeper issues within the ground supporting the carriageway structure. 

• Common subsurface risks include: 

• Voids forming beneath carriageways

• Weak or saturated subgrade

• Washout following heavy rainfall or flooding

• Localised settlement under traffic loading

These issues often go undetected until defects reappear in the same location. The result is a reactive maintenance cycle, where the same sections of carriageway repeatedly require intervention. 

This creates: 

• Rising maintenance costs

• Ongoing disruption to road users

• Increased pressure on already limited budgets

For councils delivering against RIS3 targets, this approach is no longer sustainable. 

Why surface solutions alone fall short 

Surface treatments can restore ride quality and short-term serviceability, but they do not address loss of support beneath the carriageway. 

If the underlying ground remains untreated: 

• Defects are likely to return

• Interventions become more frequent

• Asset life is reduced

In many cases, the issue lies within the underlying formation and subgrade, not the surface layers. 

A more targeted approach to maintenance 

Forward-thinking highway authorities are adopting a more proactive, asset-led approach, including: 

• Identifying carriageway sections at risk

• Investigating underlying ground conditions early

• Applying targeted remediation rather than full reconstruction

Modern ground improvement techniques make this possible without major disruption. 

Strengthening the ground without excavation 

Non-intrusive ground engineering methods allow maintenance teams to address subsurface issues quickly and precisely. Techniques such as engineered resin injection can: 

• Fill voids beneath carriageways

• Strengthen weak or variable subgrade conditions

• Restore support and reduce further movement

• Improve load-bearing performance

These methods are typically delivered without excavation or reconstruction in a relatively short timescale with reduced disruption to road users. 

This makes them particularly well suited to busy road networks where access, cost and programme are critical constraints.  

By addressing the underlying cause of failure, highways teams can: 

• Reduce repeat interventions

• Extend carriageway life

• Lower whole-life maintenance costs

• Improve network reliability and availability

This approach aligns directly with RIS3 objectives around resilience, efficiency and long-term value. 

Supporting highways teams to deliver more 

Mainmark works with highway authorities and contractors to identify and treat subsurface issues before they escalate into repeat failures. By strengthening the ground beneath carriageways using resin injection, Mainmark helps clients: 

• Break the cycle of reactive maintenance

• Deliver more durable repairs

• Reduce disruption to road users

• Make better use of constrained budgets

Looking beyond the surface 

As RIS3 drives a maintenance-first approach, success will depend on how effectively underlying risks are managed. Surface repairs alone are no longer enough. 

To improve long-term network performance, highways maintenance must go beyond the surface and address the ground conditions that drive failure. 

To conclude 

If you are seeing repeat defects or recurring issues on your carriageway network, it may be time to look beneath the surface. 

Speak to Mainmark about how targeted ground improvement can help reduce repeat repairs, extend asset life and improve network performance.