TBM Anne - HS2 Northolt Tunnel East
West London, UK (Victoria Road to Green Park Way) · 2024-2025 (Launched April 2024, completed July 2025) · £87.7bn - £102.7bn (HS2 project total, 2025 prices)
The judgement call
Account-gated at launchTBM Anne was the fourth and final TBM for the Northolt Tunnel. Named after Lady Anne Byron. Completed its 5.5km drive under London, completing the tunnel excavation.
Key engineering challenges
Tunnelling under densely populated urban areas. - Managing ground movements and settlement.
Project facts
- Client / owner
- HS2 Ltd.
- Lead contractor
- SCS JV (Skanska Costain STRABAG Joint Venture)
- Lead designers
- —
- Project type
- new build
- Scale
- Tunnel length: 13.5 km (8.4 miles) twin-bore tunnel; Drive length: 5.5 km (3.4 miles)
- Disciplines
- civil; structural; mechanical; electrical; systems; tunnelling; geotechnical
- Standards & frameworks
- UK railway standards, CDM Regulations (implied).
Sources: HS2.org.uk (https://www.hs2.org.uk/building-hs2/tunnels/twin-bore-tunnels/northolt-tunnel/) - Skanska.co.uk (https://www.skanska.co.uk/about-skanska/news-and-events/press-releases/300281/Breakthrough-Our-HS2-team-completes-excavation-of-8.4-mile-tunnel-under-the-capital) - Railway-News.com (https://railway-news.com/hs2-tbm-anne-completes-final-stretch-of-northolt-tunnel/) - GEplus.co.uk (https://www.geplus.co.uk/news/hs2-final-tbm-completes-northolt-tunnel-after-straight-forward-drive-07-07-2025/)