Recent updates to the HM Treasury Green Book reinforce a direction of travel that has been evident for some time: investment decisions are increasingly expected to demonstrate how they contribute to outcomes for places, rather than relying solely on the isolated performance of individual schemes. This has implications not only for transport appraisal, but equally for the economic development and regeneration frameworks traditionally associated with MHCLG-style business cases.
Many of the benefits associated with public investment in brownfield development and associated interventions, arise through the positive externalities of more sustainable development patterns. These include improved access to jobs and services, support for higher-density and mixed-use development, reduced reliance on private vehicles, and longer-term productivity and inclusion effects. Such impacts sit at the intersection of transport economics and economic development appraisal and are not well captured when either discipline is applied in isolation.
The 2026 Green Book does not replace established appraisal frameworks, nor does it reduce the importance of quantitative analysis. Instead, it places greater emphasis on the Strategic Case, proportionality and a clear articulation of how investment leads to change. This creates a stronger basis for integrated, place-based business cases that consider transport, land use and development outcomes together, without relying on the extension of scheme-level benefit–cost ratios beyond their appropriate limits.
Isn’t this covered by DfT TAG Wider Economic Impacts?
It is important to distinguish this approach from the long-standing treatment of land-use change within transport appraisal, including dependent development and other “level 3” wider economic impacts under TAG. When I worked for National Highways as the economic advisor for all major road projects in the midlands and the north, we would often include level 3 wider economic impacts such as dependent development for bypass schemes that had come through the Housing Infrastructure Fund or running a land use and transport interaction model to capture productivity impacts where a road scheme causes firms to relocate, where they were relevant to do so. However, these were significant transport-led infrastructure projects that were addressing a problem in the transport market, but their scale, significance and/or location meant their impacts would spill out into land, labour and product markets as a second order effect.
Integrated place-based business cases are not a way of incorporating additional impacts into a transport BCR. Rather, they reframe the investment logic by starting with a defined place, such as a station area, town centre or corridor, and assessing how transport networks, land use, market response and public-sector intervention combine to deliver economic and social value.
What we have been doing at AMION
This approach has informed our work on several of our projects over the last four years. These include projects and programmes such as the Ebbsfleet Central developments at the heart of Ebbsfleet garden city, the Hind Street regeneration in Birkenhead town centre, the Dudley to Brierley Hill light rail corridor and development areas surround several rail stations in the East Midlands. For each of these, economic appraisal has focused on how transport supports sustainable development and regeneration outcomes. In these cases, new transport infrastructure is not always the primary driver of value. Changes in land use, density and mix can themselves generate transport-related externalities, such as improved accessibility and mode shift, that are not captured within land value uplift or transport user benefits of associated infrastructure. We have agreed methodologies for capturing these externalities in a way that is consistent with TAG and MHCLG appraisal principles, although not explicitly in guidance, with multiple central government departments and regional combined authorities. These have made positive contributions to the value for money assessment of several projects.
A consistent feature of this work is a disciplined treatment of additionality, uncertainty and delivery. Integrated place-based business cases are explicit about the conditions required for development outcomes to be realised, the role of public-sector coordination, and the limits of monetisation. Where impacts cannot be robustly quantified, they are evidenced through transparent assumptions, scenario testing and alignment with policy objectives, in line with Green Book principles.
Could this be relevant to your project?
As appraisal practice continues to evolve, integrated place-based business cases provide a practical way of bringing together transport economics and economic development appraisal within a single, coherent investment narrative, where it is appropriate to do so.
If you think we can be of assistance in developing the business case for your integrated place based scheme, or would like to discuss more broadly, please feel free to get in touch with me at tommillard@amion.co.uk.