A team of 90 engineers recently completed the assembly of HS2’s second tunnel boring machine (TBM), which is set to begin excavating the second bore of the project’s 3.5 mile Bromford Tunnel into Birmingham in 2024.
Following the success of HS2’s first TBM ‘Mary Ann’, which has built over 500 tunnel rings between North Warwickshire and Washwood Heath, the new as-yet-unnamed TBM is expected to conclude its journey toward the middle of 2025.
Second giant HS2 tunnel boring machine gets ready to start digging under Birmingham: The giant 125 tonne cutterhead being moved into place© HS2
Together, the two TBMs will remove over 1.85 million tonnes of excavated land, which will be sifted and reused on nearby HS2 sites at Delta Junction.
Jules Arlaud, Tunnelling Director for Balfour Beatty VINCI said:
“Completing the assembly of the second tunnel boring machine is another major achievement for the team working on HS2’s Bromford Tunnel - a complex section of the new high-speed railway.
“Getting to this stage has required a huge amount of planning and preparation, including the disassembly and transportation of ‘Dorothy’ parts from Warwickshire, which forms the majority of the second TBM.
“Over the next few months, the team will be busy testing, checking and carrying out the final preparations, to make sure the machine is ready to start digging in spring next year.”
The new bore was largely assembled using parts from a previous TBM, ‘Dorothy’, which was used to complete a one-mile twin-bore Long Itchington Wood Tunnel in Warwickshire in early 2023. All new components for the bore were manufactured by Herrenknecht in Germany, including a new outer part cutterhead and shield.
HS2’s Senior Project Manager Catherine Loveridge said:
“With the first TBM ‘Mary Ann’ well on her way building the tunnel to take high speed trains into central Birmingham’s Curzon Street Station, it’s fantastic to see the second TBM assembled and being prepared to start digging.
“We’re now at peak construction, with over 9,750 people working on HS2 in the West Midlands and around 450 people working on this site, including many from the local area. Launching the second TBM next year means there will be more exciting jobs up for grabs for local people.”
The Bromford Tunnel programme is set to be delivered by around 450 engineers from HS2 contractor, Balfour Beatty VINCI (BBV).
Operation of the TBM will continue 24/7, and will be carried out by a specialist tunnelling team including apprentices from BBV’s sub-contractor, Tunnelcraft. The bores are expected to take roughly 16 months.
41,594 concrete segments are planned to be turned into 5,942 49-tonne rings to create the twin-bore tunnel, with the segments being produced at BBV’s pre-cast factory at Avonmouth near Bristol.