The construction of HS2’s gateway to Birmingham takes a leap forward as the huge 125-m-long TBM digging the first bore of the Bromford tunnel reaches the halfway point.
The 1,600 t machine called Mary Ann - the real name of Warwickshire-born author George Eliot - has excavated and built 2.82 km (1.75 miles) of the first bore of tunnel between Water Orton and Washwood Heath in Birmingham. The TBM started digging from a large underground box in Water Orton last year.
Driving around the clock around 40 m underground towards Washwood Heath in Birmingham, the TBM has excavated under the Park Hall Nature Reserve and River Tame and is now passing under Castle Vale. It will continue adjacent to and under the M6 before breaking through at Washwood Heath early next year.
The TBM will install a total of 20,797 concrete segments making 2,971 concrete rings to form the tunnel.
The tunnel’s 47-m deep and 18.6 m in diameter ventilation shaft at Castle Vale marks the halfway point of the TBM. The shaft will feature cross passages which will eventually link to the two tunnels either side to provide ventilation, servicing and emergency access. A ‘headhouse’ will be built on top of the shaft, and the whole structure will be complete in 2027.
The second TBM, named Elizabeth after Dame Elizabeth Cadbury by local school pupils, started building the tunnel’s second bore in March 2024 and is due to finish her journey towards the end of 2025.
The two TBMs will remove 1.87 million tonnes of excavated material, which is being sifted at the on-site slurry treatment plant and reused on nearby sites at the Delta Junction, where a complex network of 13 viaducts is being built. HS2 has built dedicated roads between these construction sites, including an access off the M6/M42 link roads, in order to take lorries off public roads.
In preparation for the arrival of the TBMs at Washwood Heath a team of 130 people built the tunnel’s west portal. Which at 22 m below ground, is the deepest of the four tunnel portals on the Midlands section of the HS2 route. The portal is at the start of a 750-m-long cut and cover structure, which is currently being excavated and built. This is where HS2 trains will emerge from the Bromford tunnel and travel below ground level, before raising up onto a series of viaducts through Birmingham’s industrial heartland and into Curzon Street Station. For further information click here and uk/65. Visit https://www.hs2.org.uk/. 35/24.
