HS2's 125-metre-long tunnel boring machine has started its second one-mile tunnel bore under Long Itchington Wood.

Nicknamed 'Dorothy', the machine completed the first tunnel drive in July 2022 after Balfour Beatty VINCI (BBV) teams worked around the clock in shifts over seven months.

In the four months following the first breakthrough, the gantries of the tunnel boring machine, which weigh over 1,000 tonnes, were brought back through the tunnel and reassembled at the north portal.

The huge cutterhead, weighing 160 tonnes and with a ten-metre diameter, was moved by road overnight in September.

The TBM's 130 tonne tail skin and eight other large pieces from the TBM's front shield and middle shield, were also transported by specialist equipment.

HS2's senior project manager for Long Itchington Wood Tunnel, 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."

This is the sixth tunnel launch on the project, but the first time a TBM has been reassembled and reused.

Four other TBMs are currently in the ground, digging twin bore tunnels under the Chilterns and London. When the TBM breaks through next summer, Long Itchington Wood Tunnel will be the first twin tunnel to be completed on HS2.

Excavation of the twin bore tunnel will produce around 500,000 tonnes of mudstone and soil, which is being processed at an on-site slurry treatment plant and separated out before being transported by a 254-metre conveyer to be used to build embankments along the route of the railway.

The TBM is named 'Dorothy' after Dorothy Hodgkin, who in 1964 became the first British woman to win the Nobel Prize in Chemistry.