National Highways Identifies 182 High-Risk Run-Off Locations, Commits to Pollution Mitigation by 2030

National Highways has published a comprehensive report identifying 182 high-priority locations across the strategic road network where outfalls or soakaways present a significant risk of pollution to surrounding waterways.

The announcement highlights the organisation’s commitment to tackling road run-off and protecting water quality as part of its wider environmental and sustainability objectives.

Run-off pollution occurs when rainwater or surface water flows over roads and paved areas, picking up contaminants such as oil, heavy metals, rubber particles, and other hazardous substances. If untreated, this polluted water can enter rivers, streams, and lakes, harming aquatic ecosystems, affecting biodiversity, and contributing to long-term water quality issues. High-risk locations are typically where outfalls discharge directly into sensitive watercourses or where existing soakaways are insufficient to treat or retain pollutants effectively.

National Highways has committed to mitigating the risk at all high-priority locations by 2030 through the installation of new or upgraded treatment facilities. These facilities are designed to capture and treat run-off before it reaches water bodies, reducing the impact of contaminants and improving the safety and resilience of the road network.

The programme is ambitious in scope: in addition to the 182 confirmed high-risk sites, the organisation expects to deliver improvements at around 250 locations in total, addressing both confirmed and potential future high-risk points.

Measures include:

• Installation of advanced treatment systems to remove hydrocarbons, heavy metals, and other pollutants

• Upgrades to existing soakaways and drainage infrastructure to improve pollutant retention and filtration

• Implementation of regular monitoring and maintenance programmes to ensure continued effectiveness

• Integration with sustainable drainage and natural filtration techniques where possible, such as swales, retention ponds, and vegetated buffer zones

Claire Hamar, Head of Environmental Strategy at National Highways, said:

“Identifying these high-risk locations is the first step in ensuring that our road network protects the environment as well as the people who use it. By 2030, we aim to significantly reduce the risk of run-off pollution entering our rivers and streams, safeguarding water quality and local ecosystems for future generations.”

The initiative aligns with broader UK and European commitments to improve water quality, meet environmental standards, and reduce the impact of urban and road-related pollution. It also reflects growing public awareness of the cumulative effects of road run-off, which has been shown to contribute significantly to river pollution through nutrients, sediment, and toxic substances.

By proactively addressing these risks, National Highways not only protects the environment but also improves resilience across the strategic road network, reducing the likelihood of environmental incidents that could disrupt traffic or require emergency response interventions.

This programme forms part of a long-term strategy to make the national road network safer, cleaner, and more sustainable, demonstrating how infrastructure management can actively support environmental protection and community wellbeing.