HS2 Birmingham to London: Final giant tunnelling machine launches towards Euston station

The final tunnel boring machine (TBM) for HS2 has begun its journey towards central London, marking a major milestone in the construction of Britain’s new high-speed railway.

Launched from Old Oak Common in west London on March 16, the 1,624-ton machine - named “Karen” - will excavate the second bore of the 4.5-mile Euston tunnel. The route will ultimately connect the new high-speed line directly into Euston railway station, the planned London terminus of HS2.

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The machine is named after Karen Harrison, one of the UK’s first female train drivers. To mark the occasion, two current drivers from Avanti West Coast - Hayleigh Richardson and Vicky Knight - were invited to take part in the launch and operate the TBM alongside engineers.

The launch follows the start of tunnelling by a sister machine, “Madeline,” earlier this year. Together, the two machines will complete the twin-bore tunnel that will bring high-speed services into central London.

Once operational, the TBM will function continuously, excavating soil and installing concrete tunnel segments in a rolling process. In total, the Euston tunnel project is expected to require nearly 50,000 segments and remove around 1.5 million tons of material.

HS2 Ltd said the launch represents the final TBM deployment across the route between London and the West Midlands. The wider tunnelling programme has already completed several major sections, including the Northolt and Chiltern tunnels.

The government has emphasised the importance of extending HS2 into Euston, describing it as critical to the regeneration of the surrounding area. Plans for the station redevelopment include new homes, jobs, and commercial investment, with the potential to deliver significant economic benefits.