UK-based High Speed Two (HS2) has launched the 125m tunnel boring machine (TBM), named Dorothy, in the second one-mile tunnel bore under Long Itchington Wood in Warwickshire.

It is said to be a crucial step in the construction of Phase One’s northern section.

This year in July, the Balfour Beatty Vinci (BBV) tunnelling team concluded a first tunnel drive using this TBM.

The TBM’s gantries, which weigh more than 1,000 tonnes, were brought back through the tunnel and reassembled at the north portal over the last four months.

HS2 stated that this is the sixth tunnel launch on the project, and four other TBMs are presently involved in the digging of twin-bore tunnels under the Chilterns and London.

Classified as a Site of Special Scientific Interest (SSSI) with complex ecosystems, Long Itchington Wood Tunnel is expected to become the first twin tunnel to be completed on HS2 after the TBM breaks through next summer.

The twin-bore tunnel excavation will provide around 500,000 tonnes of mudstone and soil.

It will be processed at an on-site slurry treatment plant and separated before being shipped by a 254m conveyer to help build embankments along the route of the railway.

HS2 Long Itchington Wood Tunnel project manager Doug Barnett said: “After celebrating HS2’s first historic tunnel breakthrough in July, this TBM reassembly and relaunch is another first for the HS2 project.

“One year after Dorothy launched for her first drive, she’s now set off for the second bore, and we look forward to seeing the next HS2 tunnel breakthrough in summer 2023.”