A 2,000-tonne TBM named ‘Dorothy’ – after Dorothy Hodgkin, who in 1964 became the first British woman to win the Nobel Prize in Chemistry – has completed its one-mile dig under Long Itchington Wood in Warwickshire.
The giant 125m long TBM, which started its journey at the tunnel’s North Portal in December 2021, broke through the wall of the reception box at the South Portal site on Friday 22 July. Nearly 400 people working for HS2’s main works civil contractor Balfour Beatty VINCI (BBV JV) have delivered this important milestone on the HS2 project.
The expert tunneling team has been working around the clock in shifts for seven months to operate the TBM, which has put 790 concrete rings in place, with each ring made from eight two-meter-long segments.
“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 tunneling engineers, TBM operators, and the construction workers at both portal sites, has pulled out all the stops to achieve this fantastic milestone," appreciated an effort hundreds of workers HS2 CEO Mark Thurston.
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.
“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,” proclaimed Trudy Harrison, Minister of State for Transport.
Creating both bores of the tunnel, the machine is removing around 250,000 cubic meters of mudstone and soil, which is being transported to the on-site slurry treatment plant where the material is separated before being reused on embankments and landscaping along the route.
A 254 meters 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 cutter head 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, and ready to launch for the second bore of the tunnel.