HS2 unveils Bromford Tunnel TBM

The 5.6km tunnel is the fourth twin-bore tunnel to be started on the high-speed rail project. The tunnel will take trains into Birmingham as they approach Curzon Street Station in the heart of the city.

The 125m-long TBM, operated by HS2 contractor Balfour Beatty Vinci, will take around 16 months to complete each bore.

HS2 Ltd CEO Mark Thurston described the unveiling as a “big construction milestone” on the HS2 project as the Bromford Tunnel TBM gets ready for its journey.

“There are nearly 9,000 people in the West Midlands working on HS2, with a 450-strong team working on this particular operation,” said Thurston.

“This is one of 350 sites well under way on HS2, helping to support over 400 firms in the region, with over £1.7bn of contract awards for local businesses so far. Work is still ramping up, with two stations in the West Midlands still to be built, so there are many more contracts up for grabs.”

After final testing, the TBM will launch from a 160x30m wide x 15m deep underground structure, which forms the east portal of the tunnel. Over the last few months, sections of the machine – including the massive 8.62m diameter cutterhead – were lowered into the box where has been assembled.

A total of 20,797 segments will be put in place by the TBM, making 2,971 concrete rings to form the tunnel. Each segment is 2m wide and 35cm thick, with each completed ring weighing around 49 tonnes.

The TBM will remove 1.87 million tonnes of excavated material, which will be sifted at the on-site slurry treatment plant and reused on nearby sites at the Delta Junction.

The TBM is named ‘Mary Ann’ after Mary Ann Evans, better known by her pen name George Eliot. Born in Nuneaton, she was an English novelist, poet, journalist, translator and one of the leading writers of the Victorian era. The name was suggested by the Warwickshire community.