Tunnel boring machine (TBM) Florence has completed a 10-mile drive under the Chilterns to excavate the longest tunnel for the HS2 project.

The journey, which lasted 2 years and 9 months ended with a breakthrough at the North Portal, near South Heath, Buckinghamshire.

Historic breakthrough for HS2’s longest tunnel© HS2 Ltd

Florence is one of two identical TBMs used to create the twin-bore Chiltern tunnel from the South Portal near the M25 to South Heath in Buckinghamshire. TBM Cecilia is now also due to breakthrough in the next few weeks.

Rail Minister Huw Merriman said:

“This ground-breaking moment for HS2 demonstrates significant progress on the country’s largest infrastructure project, with ‘Florence’ paving the way for faster, greener journeys between London and Birmingham while supporting hundreds of jobs and apprenticeships along the way.

“Today’s breakthrough of HS2’s longest tunnel highlights the momentum behind the project and the achievement is testament to the hard work and dedication of the 450-strong team helping deliver the line that will transform rail travel for generations to come.”

TBM Florence and TBM Cecilia are operated by HS2’s main works contractor, Align and were made by TBM specialists, Herrenknecht.

Each TBM is operated by a crew of around 17 people, working in shifts to keep the machines running 24/7.

HS2 Ltd Executive Chairman, Sir Jon Thompson, said:

“Today is an incredible day of HS2 and I’d like to thank the hundreds of people who’ve worked so hard over many years to make it happen. Once complete, HS2 will dramatically improve journeys between our two largest cities and also free up space on the existing mainline for more local trains.

“We’ve still got a lot of work to do, but historic moments like today really underline the huge amount of progress that’s been made and the fantastic engineering skills we have on the project.”