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Historic tunnelling success celebrated by HS2

The first tunnelling success for HS2 is being celebrated! In Warwickshire, a 2,000-ton TBM with the name “Dorothy”—after Dorothy Hodgkin, the first British woman to win the Nobel Prize in Chemistry—has finished its mile-long excavation beneath Long Itchington Wood.

The 125m long TBM began its journey at the North Portal of the tunnel in December 2021, and on Friday it made its way through the reception box wall at the South Portal site.

This significant project milestone was completed by almost 400 employees of Balfour Beatty VINCI (BBV JV), the main works civils contractor for HS2.

The TBM has installed 790 concrete rings, each made of eight two-meter-long segments, thanks to the expert tunnelling team’s round-the-clock shift work over the course of seven months.

Around 250,000 cubic metres of mudstone and soil are being removed by the machine as it excavates both bores of the tunnel. This material is then transported to the site’s slurry treatment plant, where it is separated out and reused for landscaping and embankments.

At the north portal site, a 254-meter-long conveyor that transports the excavated material over the Grand Union Canal eliminates the need for the equivalent of 30,000 HGVs from neighbourhood roads, minimising negative effects on the neighbourhood and reducing carbon emissions.

The TBM will be brought back through the tunnel over the course of the following four months while the cutterhead and front section are taken apart and moved back to the north portal. It will be put back together and prepared for launch when the tunnel’s second bore begins.

This is a fantastic milestone, and the Danny Sullivan Group is proud to have a role to play in the development of the HS2 Project. We look forward to seeing how the project develops further in the years to come.