Revealed: The huge machines that will spend around three years digging HS2 tunnels

The first pictures of the machines that will spend years digging HS2 tunnels have been released.

The Tunnel Boring Machines (TBMs) will be digging the longest and deepest HS2 tunnels for around three years.

The TBMs are 170m long, and each weigh roughly 2,000 tonnes. They're currently being built in Germany, and after they're completed, the first two machines will be taken apart before making their way to Britain, and then reassembled.

They will dig from just inside the M25 to Buckinghamshire, and once they start they're expected to run non-stop for three and a half years until the tunnels are complete, only stopping for Christmas and Bank Holidays.

The tunnels the machines will dig are due to go as deep as 80m below ground. Both tunnels will also be lined with 112,000 concrete segments between them, which weigh, on average, 8.5 tonnes each.

The public being invited to vote to name the TMBs based on a shortlist of three names chosen by school children and inspired by "female scientific and medical pioneers."

The two names with the most votes will be chosen, and the three names to choose from are:

• Celia, after Cecilia Payne-Gaposchkin, an astrophysicist and astronomer

• Florence, after Florence Nightingale, the founder of modern nursing

• Marie, after Marie Curie, the first woman to receive a Nobel Prize

Read more:

• HS2: What does it mean for me?

• HS2 explained: What is it, where's it going, and how's the project doing?

• HS2 protestors 'self-isolate' in trees to stop woodland being chopped down