Convening the Sector on Water Management at Interchange 25
Interchange has become one of the UK’s most important spaces for organisations shaping the future of transport infrastructure. As the only large-scale platform dedicated to integrating, decarbonising and digitising UK transport networks, it brings together local authorities, national operators, and supply chain partners who are all focused on creating more resilient and efficient systems.
For Tarmac, Interchange is a place to listen, collaborate, and help shape solutions to shared national challenges. At Interchange 25, we convened a dedicated roundtable to explore how the sector can better manage stormwater, pollution, and runoff as climate pressures intensify and urban environments continue to grow.
Understanding the Challenge of Highway Runoff
Highway runoff is now recognised as one of the most pressing environmental issues facing network operators and local authorities. Participants at the roundtable highlighted concerns including pollution from hydrocarbons and tyre wear, the scale of managing 22,000 outfalls on the strategic road network, and the uncertainty of future
funding to support long term interventions.
Delegates discussed ongoing national efforts to develop improved carriageway solutions, apply nature-based techniques, and create more robust monitoring. While runoff continues to rise up risk registers, clarity around support through the RIS3 investment period was a shared priority.
Learning From Local Authority Leadership
Waltham Forest Council shared its experience of moving to a preventative, long term approach following several major flood events. The authority has responded to climate pressures and dense urbanisation with a package of measures designed to improve resilience. This includes:
permeable paving solutions to support drainage
stormwater storage delivered through tanks set within carriageways
close engagement with stakeholders to build political support
The council emphasised the importance of securing collaboration across multiple organisations to drive meaningful change, while recognising the financial pressures that often limit long term planning. Attendees also reflected on work in places such as Mansfield, where water company support has enabled more ambitious projects.
Planning for Resilient Streets and Networks
A consistent theme was the need to revive long term approaches to drainage and stormwater management. Participants noted that infrastructure interventions commonly delivered decades ago have become less frequent despite climate related risks increasing. This has created a need to refocus on measures that provide resilience over the lifetime of an asset.
Attendees also considered the challenge of installing preventative systems in areas that have not previously experienced flooding. Forthcoming flood maps from the Environment Agency were seen as an opportunity to highlight future risk more clearly and support early engagement with communities about the need for retrofit solutions.
Water Quality and Funding Pressures
While flooding has gained political visibility, several contributors emphasised that water quality requires greater attention. The group discussed how polluted runoff continues to affect waterways and ecosystems and noted that improving water quality must sit alongside flood mitigation as a sector priority.
Funding remained a central issue, particularly for local authorities operating with constrained budgets. Attendees recognised the growing role of metro mayors, devolved authorities and combined authorities in advocating for investment and ensuring water management is embedded within broader infrastructure and housing strategies.
Why This Roundtable Matters
The roundtable created a collaborative space for open and practical discussion of the challenges facing the sector. The conversation reinforced three shared needs across the value chain:
to improve water quality and reduce the environmental impact of runoff
to embed long term, resilient interventions that support climate adaptation
to secure the investment required for councils to plan beyond short term fixes
Looking forward
By convening partners from across the industry, Tarmac helped elevate water management as a collective responsibility and a central element of future highway resilience. We remain committed to supporting local authorities and industry partners to develop practical, more sustainable solutions that protect communities and strengthen networks in a changing climate.
