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Engineering vehicles & heavy plant
Engineering vehicles & heavy plantTunnel Boring Machine (TBM)

TBM Emily - HS2 Northolt Tunnel East

West London, UK (Victoria Road to Green Park Way) · 2024-2025 (Launched February 2024, completed June 2025) · £87.7bn - £102.7bn (HS2 project total, 2025 prices)

The judgement call

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TBM Emily was the third of four TBMs for the Northolt Tunnel. Named after Emily Brontë. It completed its 3.4-mile drive under London.

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); TBM diameter: 9.11m
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/) - New Civil Engineer (https://www.newcivilengineer.com/latest/hs2-third-london-tbm-extracted-from-ground-29-07-2025/) - LinkedIn (https://www.linkedin.com/posts/british-tunnelling-society_third-hs2-tbm-completes-drive-beneath-london-activity-7338851721093242880-kZ7O)