HS2 has launched the last TBM to bore tunnels for the new high-speed railway in the West Midlands.

The 125m-long TBM has started its journey to dig the second bore of HS2’s Bromford Tunnel, between the east portal at Water Orton in North Warwickshire and the west portal at Washwood Heath in Birmingham.

The 5.6km twin-bore tunnel will take high speed trains in and out of Birmingham, with a series of viaducts between Washwood Heath and Curzon Street Station taking trains to the city centre.

The majority of TBM Elizabeth, including the gantries and the centre part of the cutterhead, have been reused from TBM Dorothy after completing the 1.6km twin-bore Long Itchington Wood Tunnel in Warwickshire last year.

At 8.62m in diameter, the Bromford Tunnel is smaller than the 10m-diameter Long Itchington Wood Tunnel because trains will be travelling slower on the approach to Birmingham Curzon Street Station. For this reason, TBM Elizabeth needed a new outer part cutterhead and a new shield, which were manufactured by Herrenknecht.

TBM Elizabeth is named after Dame Elizabeth Cadbury, who spent her life campaigning for the education and welfare of women in Birmingham.

The first TBM, which launched in June last year, has completed around one-third of the drive towards Birmingham. TBM Mary Ann – the real name of Warwickshire-born author George Eliot – has tunnelled under the Park Hall Nature Reserve and is currently near the River Tame. It will continue adjacent to the M6 motorway at a depth of 27m before breaking through at Washwood Heath later this year. TBM Elizabeth is due to finish its journey in autumn 2025.

The full Bromford Tunnel programme is being delivered by around 450 people working for HS2’s contractor Balfour Beatty Vinci (BBV) and this is the fourth and final TBM launch for this contract. A tunnelling team working for BBV’s sub-contractors Tunnelcraft and Solihull-based Rorcon are operating both TBMs around the clock.

HS2’s senior project manager, Catherine Loveridge, said the project was now “at peak construction”, using many local companies and local skills.

Tunnelcraft has recruited nine tunnelling apprentices, including formerly unemployed people from the local area.

“This massive feat of engineering is providing a unique opportunity for people from the local area to work with us, learning new skills and qualifications in the process,” said Tunnelcraft managing director Cormac Hicks.

“We have a range of entry role positions still available and would encourage local people to get in contact. There has never been a more promising time to start a career in UK tunnelling.”

BBV awarded Solihull-based Rorcon a subcontract in 2023 to provide specialist tunnel labour for the Bromford tunnels. It has around 60 people, including one apprentice, working on the Bromford Tunnel programme.

Both TBMs will remove a total of 1.87 million tonnes of material, which is sifted at the on-site slurry treatment plant and reused on HS2’s nearby sites at Delta Junction, where a network of 13 viaducts is being built. HS2 has built dedicated roads between the construction sites, including an access off the M6/M42 link roads, in order to take lorries off public roads.

Both TBMs will install a total of 41,594 concrete segments, creating 5,942 rings to make the twin bore tunnel. Each ring weighs 49 tonnes. The segments are being produced at BBV’s pre-cast factory at Avonmouth near Bristol.