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27 Jul 2022

HS2 Historic Tunnelling Breakthrough Made With Dorothy the Massive Tunnel Boring Machine

HS2 Historic Tunnelling Breakthrough Made With Dorothy the Massive Tunnel Boring Machine
HS2 Ltd celebrates the historic tunnelling breakthrough of a 2,000-tonne Tunnel Boring Machine named 'Dorothy', which has completed a one-mile dig under Long Itchington Wood in Warwickshire.

HS2's historic tunnelling breakthrough began in December 2021 at the tunnel's North Portal and travelled one mile under Long Itchington Wood in Warwickshire, breaking through at the South Portal on Friday 22 July.

The'125m long Tunnel Boring Machine (TBM)'was named 'Dorothy' after Dorothy Hodgkin, who in 1964 became the first British woman to win the Nobel Prize in Chemistry.

The team have worked around the clock to deliver the tunnel and preserve local ancient woodland

Nearly 400 Balfour Beatty VINCI contractors have delivered the project, with the tunnelling team working around the clock for seven months.

The tunnelling team laid 790 concrete rings with Dorothy; each ring made from eight two-metre-long segments.

In creating both bores of the tunnel, the machine is removing around 250,000 cubic metres of mudstone and soil. This material is then being moved to the on-site slurry treatment planet to be separated out before'being reused on embankments and landscaping along the route.

The tunnel preserves the ancient woodland above, which is classified as a Site of Special Scientific Interest (SSSI) and has complex ecosystems that have taken hundreds of years to establish.

A 254 metres long conveyor at the north portal site, which takes the excavated material over the Grand Union Canal, removes the equivalent of around 30,000 HGVs from local roads, reducing impacts on the local community and cutting carbon.

Over the next four months, the cutterhead and front section of the TBM will be dismantled and transferred back to the north portal, while the bulk of the machine will be brought back through the tunnel. It will be reassembled, ready to launch for the second bore of the tunnel.

HS2 Ltd's CEO Mark Thurston said:

'This is a historic moment for the HS2 project, and I'd like to congratulate everyone involved in delivering it. The 400-strong team, including tunnelling engineers, TBM operators and the construction workers at both portal sites, have pulled out all the stops to achieve this fantastic milestone.

'This milestone demonstrates the significant momentum behind Britain's'new zero-carbon railway, creating thousands of jobs and apprenticeships, along with hundreds of opportunities for businesses right across the country, helping fuel our economic recovery.'

HS2 minister Trudy Harrison said:

'As Dorothy paves the way for journeys between Birmingham and London, we continue to strive towards delivering a greener, faster and more direct transport network. And as we deliver alongside our record breaking Integrated Rail Plan, we're boosting the economy, delivering over 25,000 jobs.'

Balfour Beatty VINCI's managing director, Michael Dyke, said:

'This is a momentous moment, not only for Balfour Beatty VINCI, but for everyone involved in delivering HS2. Thanks to the hard work and dedication of our team,'Dorothy ' our cutting-edge Tunnel Boring Machine'' has made history, becoming the first to safely and successfully breakthrough along the route.

'With Dorothy's journey now concluded, I am looking forward to celebrating even more milestones throughout the rest of the year and beyond, as we continue to help build Europe's largest infrastructure project.'