Hs2 make historic breakthrough with TBM Dorothy

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HS2 is celebration after its first tunnel breakthrough at the massive project, Dorothy the TBM machine made the first among many new tunnels on the project complete.

The 2,000t custom-made tunnel boring machine (TBM) called Dorothy, ‘Dorothy’ – after Dorothy Hodgkin, who in 1964 became the first British woman to win the Nobel Prize in Chemistry the firm has concluded a one-mile dig under Long Itchington Wood in Warwickshire to make the first mile of the 64 miles of tunnels.

The tunnel will span intermittently between London and Manchester It is the first of 64 miles of intricate tunnels under Europe’s largest infrastructure project.

The long TBM which is 125 metres long commenced its operation at the tunnel’s North Portal in December 2021 and reached the South Portal site on 22 July.

There are around 400 people working for HS2’s main works civil contractor, Balfour Beatty VINCI (BBV JV) they have been involved in the tunnelling breakthrough works, that have been completed in seven months.

The tunnel is designed to protect the ancient woodland above, which is classified as a Site of Special Scientific Interest (SSSI). It features complex ecosystems that took hundreds of years to grow.

Mark Thurston HS2 CEO 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.”

450m-long Wendover Dean Viaduct, which is said to be Britain’s first key rail bridge to be built with a double composite structure which is discussed in the video below by the HS2 CEO.

HS2 is expected to play a significant part in the government’s £96bn Integrated Rail Plan, which includes the development of three new high-speed lines, addition of extra seats, and reduction in travel times.

Balfour Beatty VINCI’s Managing Director, Michael Dyke, commented saying that : “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.”

By creating both bores of the tunnel, the machine needs to remove around 250,000 cubic metres of mudstone and soil, which is being transported to the on-site slurry treatment plant where the material is separated out before being reused on embankments and landscaping along the route.

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.

The cutterhead and front section of the TBM will be dismantled and transferred back to the North portal over the next four months, 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.