Second giant HS2 tunnel boring machine prepares to start digging

A team of 90 specialist engineers has completed the assembly of HS2’s giant tunnel boring machine (TBM) which will dig the second bore of the 3.5 mile Bromford Tunnel into Birmingham. In an assembly operation to move sections of the machine into a 12-metre deep launch pit, two 600 tonne cranes lifted the huge 125 tonne cutterhead into place at the front of the 125 metre long machine in the pit bottom.

The first TBM, named ‘Mary Ann’ after Mary Ann Evans – the real name of Victorian writer George Eliot who was born in Nuneaton – started digging the first bore from the east portal site near Water Orton in August 2023. It has already built more than 500 tunnel rings, which is 0.6 miles of the 3.5 mile long tunnel between North Warwickshire and Washwood Heath in Birmingham.

The name of the second TBM will be revealed before it launches in Spring next year. ‘Mary Ann’ is set to break through at the end of 2024, with the second TBM planned to complete its journey in the middle of 2025.

Both TBMs will remove 1.87 million tonnes of excavated material, which will be sifted at the on-site slurry treatment plant and reused on HS2’s nearby sites at Delta Junction, where a complex network of nine viaducts is being built.