The development at the one-mile-long twin-bore tunnel sees vital elements, including three cross passages, concrete finishing works and base slabs, and emergency and maintenance walkways complete.
It comes before the internal fitting out of the tunnel with systems needed to operate the railway, including the power, track and signalling.
The tunnel is the first of five twin-bore tunnels on the HS2 project to reach this stage. In all, 27.4 miles of the route between London and the West Midlands are in deep twin-bore tunnels.
Work to create the Long Itchington Wood Tunnel began in June 2020. The 125-metre-long tunnel boring machine used to excavate the tunnel, Dorothy (after Dorothy Hodgkin, the first British woman to win the Nobel Prize in chemistry), was launched in December 2021 and finished excavating both bores of the tunnel in March 2023.
Some 750,000 tonnes of spoil was excavated and reused to build embankments along the route of the railway.
Long Itchington Wood Tunnel is being built by Balfour Beatty Vinci (BBV), which is constructing 56 miles of HS2 between Long Itchington in Warwickshire to the centre of Birmingham and on to Staffordshire.
BBV tunnelling director Jules Arlaud said: “The scale of this achievement is enormous. A dedicated workforce of around 380 people have worked tirelessly over the past five years to reach this latest phase of construction, where the tunnels are now fitted with three cross-passages and the concrete finishing works, base slabs, and walkways are also complete.
“Throughout this project, our expert tunnelling team have installed a total of 1,582 concrete rings across both tunnels, with each ring made from eight two-metre-wide segments, each weighing up to 8 tonnes.”
Doug Barnett, senior project manager for HS2 Ltd, added: “It’s a small part of HS2 but it’s been four and a half years of my life in which I’ve seen this construction go from its very embers to nearing completion – a really proud moment for me personally.
“Long Itchington Wood Tunnel is a tremendous feat of engineering and would not have been possible without a huge amount of continuous work put in over the past five years – I’d like to thank everyone involved working both onsite and behind the scenes for their support.”
The four other twin bore tunnels on HS2 are:
- The 3.5-mile Bromford Tunnel, which carries the railway into Birmingham, with both tunnel drives expected to be completed this year
- The 10-mile long Chiltern Tunnel, which takes the railway beneath the Chiltern Hills, with both tunnel drives being completed in early 2024 and internal works on the tunnels now ongoing
- Northolt Tunnel, an 8.4-mile tunnel between Old Oak Common and outer London, which is being built by four tunnelling machines, with the first drive completed in December 2024
- The 4.5-mile Euston Tunnel between Old Oak Common and central London, where the tunnel boring machines have yet to be launched, pending confirmation of plans for the Euston terminus.
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