The Department for Transport (DfT) has released new guidance on quantifying carbon in the planning of local transport schemes and strategies. The document, available here, provides a structured framework for assessing carbon impacts during the development of Local Transport Plans (LTPs) and other strategic processes.
At first glance, this guidance is closely aligned with the Quantified Carbon Reductions document drafted under the Johnson government but never published. City Science was consulted on that earlier draft, and the refreshed version has now been released under the name Quantified Carbon Guidance.
Quick Summary
Local authorities have a critical role in supporting the decarbonisation of transport, the UK’s largest emitting sector. Incorporating carbon assessments into strategy and scheme development is essential to achieving this.
The new guidance provides advice on how local authorities can include quantified carbon analysis across three key stages:
- Strategy development
- Scheme development
- Post-delivery evaluation
It also defines three categories of carbon sources:
- User carbon
- Infrastructure capital carbon
- Infrastructure operational carbon
Assessment methodologies are provided for each, recognising that while there is no single approach that applies universally, some methods are consistently replicable across areas. Importantly, the guidance emphasises tailoring assessments to local context and requirements.
Why This Matters
At City Science, much of the content in the new guidance reflects work we already do with our clients. Supporting local authorities in the transition to low-carbon transport has long been part of our core practice.
Even so, its publication is an encouraging step. By aligning around clear, consistent principles, the DfT is providing a stronger foundation for local authorities to act confidently and decisively in reducing transport emissions.
Key implications for local authorities:
- Potential impact on funding
DfT’s Transport Decarbonisation Plan (2021) stated that local authority funding would be linked to decarbonisation ambition. The new guidance provides authorities with the toolkit to evidence ambition effectively. Its publication may signal a return to funding approaches that prioritise decarbonisation outcomes. - Complementing existing guidance
The guidance sits alongside existing standards, such as PAS 2080, which focus on later stages of scheme development (e.g. business case development) and are not transport-specific. In contrast, the Quantified Carbon Guidance offers targeted advice for transport planning and placemaking, with a strong focus on the strategic stage, arguably the most important phase for embedding effective carbon reduction. - Integration into core processes
The document makes explicit reference to Local Transport Plans, Transport Strategies, and Transport Schemes. Going forward, robust carbon assessments should form a standard part of these processes. With its strong emphasis on placemaking, elements of the guidance could also inform Local Plans, particularly given the recent trend toward merging upper and lower-tier authorities. - Reliance on outdated assumptions
The guidance recommends using the DfT TAG data book as a source for carbon forecasts. However, the UK is not currently matching the rate of electric vehicle (EV) rollout assumed in TAG, creating a risk that carbon emissions will be underestimated. Local authorities may need to supplement TAG data with updated, realistic EV adoption forecasts to avoid underestimating mitigation requirements.
Don’t overlook the STB Carbon Assessment Playbook
One notable omission from the Quantified Carbon Guidance is the STB Carbon Assessment Playbook, a free-to-access tool owned by the Sub-national Transport Body (STB) community.
Developed with input from the DfT and with City Science playing a key role, the Playbook provides strategic, area-wide support for carbon assessment. It is particularly valuable in the early stages of planning and is highly relevant not only to transport authorities but also to local authorities preparing Local Plans.
You can access it here: STB Carbon Assessment Playbook.
Although it isn’t referenced in the new DfT guidance, we strongly recommend it to local authorities and planners. It’s especially valuable when looking beyond transport authorities, for example, for local authorities developing Local Plans.
Want to know more?
The publication of the DfT’s Quantified Carbon Guidance is an important milestone for transport decarbonisation in the UK. By embedding robust carbon assessment into strategies and schemes, local authorities will be better equipped to deliver meaningful emissions reductions, while also positioning themselves to align with future funding priorities.
If you have questions about how the new Quantified Carbon Guidance works in practice, how to connect it with the STB Playbook or how to adapt these tools to your local context, please don’t hesitate to reach out. We’d be more than happy to discuss how best to apply this guidance to real-world challenges.