Unique HS2 tunnel portal completed
25 Apr 2025Our Align JV builds tunnel extensions for HS2 to stop sonic booms from 200mph trains entering the 10-mile Chiltern Tunnel.
8th Dec 2020
Our Align JV takes delivery of HS2 giant tunnelling machines
HS2’s first two giant Tunnel Boring Machines (TBMs), named Florence and Cecilia, have arrived in the UK. Work on the project’s first tunnels, which are being constructed by our Align joint venture, starts early next year.
HS2’s first two giant Tunnel Boring Machines (TBMs) have arrived in the UK and will be ready to start work early next year.
The two enormous 2,000 tonne machines, named Florence and Cecilia, will now be meticulously reassembled, tested and commissioned by an expert team of tunnelling engineers, before they start work on the project’s first tunnels, which are being constructed by our Align joint venture.
The 10-mile-long ‘twin bore’ Chiltern tunnel will be the longest on the project, with the TBMs set to be underground, working 24/7 for more than three years.
The launch of our first tunnelling machines will be a defining moment in the history of HS2 – and our work to deliver a high speed railway that will offer a low-carbon alternative for journeys across the UK. Construction is now well underway, with more than 13,000 jobs supported by the project, both directly and in our UK-wide supply chain. The arrival of Florence and Cecilia is a major step forward and our expert team will now work to assemble, test and commission them before their launch next year.
Mark Thurston Chief Executive
Designed specifically for the mix of chalk and flints under the Chilterns, the two identical TBMs will dig separate tunnels for north and southbound trains, with Florence set to launch first and Cecilia to follow a few weeks behind.
Each machine operates as a self-contained underground factory, which as well as digging the tunnel, will also line it with concrete wall segments and grout them into place as it moves forward at a speed of 15 meters a day.
Each tunnel will require 56,000 segments, which will all be made on site. A crew of 17 people will operate each TBM, working in shifts to keep the machines running around the clock. They will be supported by more than 100 people on the surface, managing the logistics and maintaining the smooth progress of the tunnelling operation.
Now that the parts have arrived the detailed job of assembling and commissioning the machines has begun. There are also considerable other activities continuing on our site to prepare for the launch of Florence and Cecilia next year. This includes the construction of a factory that will manufacture the concrete segments to be used to line the tunnel and a slurry treatment plant that will process material from the tunnels.
Daniel Altier Align Project Director
Built by Herrenknecht at its factory in Germany, the two 170m long machines were transported to the UK in more than 300 separate shipments over the course of two months, with the parts now safely delivered to the Align Chiltern tunnel site, to the west of London just inside the M25.
Our Align Joint Venture expects to recruit 1,200 vacancies, with more than 100 opportunities for apprentices. They plan to target their recruitment and investment in upskilling local people who are currently unemployed, with a particular focus on women, under 25s and those with disabilities.
Facts and figures – The Chiltern tunnel TBMs:
- The tunnels will go as deep as 80m below the ground – ensuring communities and countryside above are not impacted by the railway
- The size of the TBM cutterhead which will bore the tunnels is just over 10m
- Taking into account the thickness of the tunnel walls, the internal diameter of the tunnels in which the trains will pass through will be 9.1m.
- The tunnels will be lined with 2m X 4m concrete segments weighing on average 8.5 tonnes each
- The cutter head will rotate at a speed of up to 3.2rpm with the machine expected to cover 15.6metres per day.
- The total volume excavated by both TBM is 2.7million cubic metres
- The TBMs are steered by tiny adjustments to the hydraulic rams that grip the tunnel wall to move forward.
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