The TBMs will excavate tunnels, reducing the environmental impacts in rural areas.

What is HS2?

HS2 is a state-of-the-art, high-speed line critical for the UK’s low-carbon transport future. It will provide much-needed rail capacity across the country, and is integral to rail projects in the North and Midlands – helping rebalance the UK economy.

The TBMs

Early in 2021, two 2000 tonne tunnelling machines measuring over 170 metres each will be launched at a site by the M25 to bore 10 miles each underneath the Chilterns in Buckinghamshire.

A TBM is used to excavate tunnels through a variety of soil and rock in dense urban areas and to reduce environmental impacts in rural areas.

Both machines are specifically designed for the mix of chalk and flint they will encounter under the Chilterns. Operating a ‘continuous boring’ technique, they are expected to take around 3 years to excavate the 9.1m metre diameter tunnels which will be lined with concrete as they go. The TBMs will convert the spoil into slurry which will be pumped back to the Align main site where it will be treated before being used for landscaping on-site, removing the need for additional HGVs on local roads.

Naming the Tunnel Boring Machines

Thank you to the thousands who cast a vote for their favourite STEM pioneer in our Tunnel Boring Machine (TBM) naming competition. Three were shortlisted; Florence Nightingale, Cecilia-Payne Gaposchkin and Marie Curie.

The eventual winners – Florence and Cecilia – were suggested by students at Meadow High School in Hillingdon and The Chalfonts Community College, Buckinghamshire, inspired by female scientific and medical pioneers.

Find out more about the inspirational women please click here.

Around 32 miles of the high-speed line route from London to Birmingham will be in tunnels and our first two TBMs will be transported to the launch site later in the year.

• The TBMs are 170m in length – nearly 1.5 times the length of a football pitch.
• Each one weighs roughly 2000 tonnes – the equivalent of 340 African bush elephants.
• When they start they will run non-stop for 3.5 years.
• The tunnels will go as deep as 90 metres (m) 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 10.26m, roughly the height of two giraffes standing on top of one another.
• The internal diameter of the tunnels in which the trains will pass through will be 9.1m, slightly larger than two London buses stacked on top of one another.
• The tunnels will be lined with concrete segments that will be 2m x 4m and weigh on average 8.5 tonnes each.
• 112,000 of these concrete segments will be required to complete both tunnels.

Visit the HS2 Website for more https://www.hs2.org.uk/