Video | HS2 TBM breaks through after 16km drive

HS2’s first giant tunnelling machine broke through this week at the end of its 10-mile (16km) journey under the Chilterns. It has excavated the longest tunnel on the HS2 route.

The enormous 2,000t tunnel boring machine (TBM), named Florence, is one of 10 machines excavating the 32 miles of tunnel on the new railway linking London Euston with Birmingham. It was the first to launch, in May 2021.

A second TBM, Cecilia, is excavating the parallel twin-bore tunnel, which is due to break through in the coming weeks.

Designed specifically for the geology under the Chilterns, each TBM is an underground factory – excavating the tunnel, lining it with 56,000 precast concrete segments and grouting them into place as it moves forward at an average speed of 16m per day.

Each TBM is operated by a crew of around 17, working in shifts to keep the machines running 24/7. They are supported by more than 100 people on the surface, managing the logistics and maintaining the smooth progress of the tunnelling operation.

The TBMs are operated by HS2’s main works contractor, Align – a joint venture formed by Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick. The machines were made in Germany by TBM specialist Herrenknecht.

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