National Highways Launches Design Playbook to Tackle Toxic Road Runoff

National Highways has unveiled a new design playbook aimed at addressing hazardous chemicals entering watercourses from road runoff, although some campaigners argue it falls short of its intended goals.

Stephen Elderkin, National Highways’ Director of Environmental Sustainability, explained that the playbook is designed to implement a “systematic, factory-like process” for designing outfall and soakaway mitigation measures. The initiative comes amid growing concerns over pollution from the Strategic Road Network (SRN) in England, where runoff can carry microplastics, hydrocarbons, toxic metals, and other contaminants into rivers and streams.

“We take pollution from runoff incredibly seriously,” Elderkin said. “It can contain heavy metals, hydrocarbons, tyre fragments, and other particulates. Without proper management, this runoff poses risks to water bodies, public health, and ecosystems.”

By February of this year, National Highways had inspected 1,236 outfalls and soakaways across the SRN, identifying 107 locations that required mitigation measures.

Following additional assurance checks, the organisation now expects the full programme over the next five years to include interventions at approximately 250 sites.

The playbook’s risk assessments are based on factors such as traffic volume at each discharge point, the surface area contributing to runoff, and the expected pollution load. While the agency asserts the framework will streamline and improve mitigation efforts, campaigners have voiced concerns that the measures may not accelerate the process quickly enough to prevent contamination of rivers and streams.