Thames Tideway Tunnel (Cofferdam Works)
London, UK (River Thames) · 2016–2025 (overall project) · £4.6bn (overall project, 2025 prices)
The judgement call
Account-gated at launchSignificant use of the River Thames for transporting over 50% of construction and excavated materials, reducing road traffic and environmental impact. - Development of innovative and site-specific designs for each of the 34 interception sites due to unique ground conditions and urban constraints. - Effective management of engineering solutions, mitigation strategies, and continuous monitoring to overcome complex tunnelling challenges.
Key engineering challenges
Constructing large temporary cofferdams in the tidal River Thames. - Managing complex logistics and environmental impacts in a densely populated urban area. - Deep tunnelling beneath a major river while intercepting 34 combined sewer overflows. - Coordinating multiple contractors and design teams across different sections of the tunnel.
Project facts
- Client / owner
- Tideway (Bazalgette Tunnel Limited)
- Lead contractor
- FLO JV (Ferrovial Construction and Laing O'Rourke JV) for Central Section cofferdams; other JVs for West and East sections.
- Lead designers
- Jacobs (Program Manager), AtkinsRealis & Arup (West Tunnelling), FLO JV (Central Section permanent works)
- Project type
- new build
- Scale
- 25km tunnel length, 7.2m tunnel diameter; various large temporary cofferdams
- Disciplines
- Civil; Structural; Geotechnical; Marine; Environmental; Tunnelling; Wastewater Engineering
- Standards & frameworks
- NEC3 (design and construct contracts), UK environmental regulations, various British Standards for civil engineering.
Sources: Tideway London: Cofferdam fully removed at Tideway's Blackfriars site (https://www.tideway.london/news/site-news/2024/august/cofferdam-fully-removed-at-tideway-s-blackfriars-site/) - Ferrovial: Marine Engineering at the Thames Tideway Tunnel Project (https://www.ferrovial.com/blog/en/2021/06/marine-engineering-at-the-thames-tideway-tunnel-project-part-ii/) - Water Projects Online: Thames Tideway Tunnel - Cofferdams (https://waterprojectsonline.com/wp-content/uploads/case_studies/2020/Thames-Tideway-Cofferdams-2020.pdf) - BBC News: Thames Tideway Tunnel super sewer completed (https://www.bbc.com/news/science-environment-68464798) - Jacobs: Thames Tideway Tunnel (https://www.jacobs.com/projects/thames-tideway-tunnel) - AtkinsRealis: Thames Tideway Tunnel West (https://www.atkinsrealis.com/en/projects/thames-tideway-tunnel-west)