From net zero targets to real-world road maintenance

Researchers at the University of Exeter have been developing a new carbon budgeting tool designed to support decarbonisation decision-making in the highways sector.

The tool has been created by Xiaoyu Yan, Professor in Sustainable Energy Systems, and Xiaocheng (Sam) Hu, Impact Fellow with Green Futures Solutions. It translates national carbon targets into a practical, service-level framework, helping local authorities explore how highway maintenance emissions evolve over time and how they align with legally binding carbon budgets and net zero pathways.

The UK has legally binding carbon budgets and a net-zero-by-2050 target, with the Climate Change Committee setting out sectoral pathways showing how emissions must fall. However, for a local authority deciding how to maintain roads next year, those national targets can feel abstract.

Highway maintenance emissions are persistent and difficult to eliminate. They are embedded in asphalt, concrete, plant and energy use, and routine maintenance cycles lock in carbon for decades. Despite this, most decisions are still made project by project, rather than against a finite, time-bound carbon budget.

This raises a simple question: what if highway services were managed within a defined carbon budget aligned to national pathways?

To explore this, a trajectory-based carbon budgeting framework has been developed. The framework translates national decarbonisation pathways into service-level carbon budgets, tracks emissions over time, and identifies residual emissions at a chosen net zero target year.

The framework is accounting-based, transparent and adaptable to different data contexts. It does not prescribe solutions; instead, it clarifies constraints. One insight stands out: even under ambitious pathways, residual emissions remain.

Once those residuals are made explicit, the conversation changes. It becomes less about whether offsetting is needed at all, and more about the scale, timing, durability and governance of carbon removal.

The framework has been implemented in an interactive tool to support scenario exploration and practical decision-making for local authorities and infrastructure planners. While developed for highway maintenance, the approach is transferable to other infrastructure services characterised by long-lived assets and recurring emissions.

If you work in local government, infrastructure planning or climate strategy, a conversation is welcomed about how national targets are being translated into operational carbon limits.

The tool and accompanying guidance are due to go live in the coming weeks.