Thames Tideway Tunnel: Social Impact
This report evaluates the social impact of Tideway’s Legacy Programme, which aimed to deliver lasting societal benefits beyond the core environmental purpose of the Thames Tideway Tunnel. Using a robust Social Cost Benefit Analysis aligned with HM Treasury Green Book guidance, the report identifies 11 Valuation Focus Areas (VFAs), including greenhouse gas reduction, health and safety, inclusive employment, local hiring, STEM engagement, and public realm improvements.
Key findings reveal that for every £1 spent, Tideway generated £1.72 in social value, with peak Benefit Cost Ratios exceeding 4:1 in later years. Highlights include over 80,000 young people engaged in STEM, more than 1,200 previously workless individuals employed, significant reductions in carbon emissions and HGV traffic, and pioneering initiatives like the EPIC safety programme and Active Row youth engagement.
Tideway’s commitment to measuring only “additional” impacts — those beyond regulatory or planning obligations — sets a new standard for credibility in infrastructure legacy reporting. The report concludes with lessons for future projects on integrating social value from the outset and establishing measurable, provable, and lasting legacy outcomes.
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Image credit: Tideway