The second enormous tunnel boring machine (TBM) constructing HS2 under the Chiltern Hills reached its goal early evening on March 21, completing a journey started in June 2021.

Named Cecilia, this colossal 2,000-tonne machine joined her twin, Florence, after a 10-mile underground drive, reaching the site near Wendover, Buckinghamshire, on February 27.

Together, Cecilia and Florence created twin-bore tunnels up to 80 metres deep, excavating three million cubic metres of chalk in the process.

Weekly, these engineering marvels laid 56,000 pre-cast concrete tunnel segments, grouting them into place.

These machines, manufactured in Germany by TBM specialists Herrenknecht, operated like underground factories with an average progression speed of 16 metres per day.

Once operational, HS2 trains will journey through the Chiltern tunnel – the line’s longest tunnel – at speeds of nearly 200mph.

This will significantly reduce trip times between Britain’s two largest cities.

Moreover, the new high-speed line will alleviate traffic on the West Coast Mainline, paving the way for more local services on this heavily utilised Victorian route.

It is anticipated that the HS2’s opening will almost double rail capacity between London and the West Midlands, thus improving the reliability of services and spurring economic growth.

HS2 Ltd’s head of civil works for this section of the route, Mark Clapp, said: "Today is a remarkable achievement for all concerned.

"Cecelia’s arrival completes excavation of HS2’s 10-mile twin-bore tunnel, but it’s only the end of the first chapter in the story of building Britain’s high-speed railway under the Chiltern Hills.

"Several years of intensive, world-class engineering lie ahead of us to complete the tunnels’ four ventilation shafts plus headhouses; install the mechanical and electrical plant and machinery, slab track and overhead electrical wires before trains begin passing through at 200mph."

Align, a conglomerate of three international establishment companies: Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick, oversaw the operation of both TBMs.

Align’s Underground Construction Director, Didier Jacques said: "Ten miles is a long drive for a TBM, with a typical average being around three miles.

"The complexity and technically challenges of completing such a long drive for both our TBMs has been significant, however, I am delighted that as a team, we have risen to the challenge."

About 17 crew members, bolstered by over 100 people on the surface, kept these machines running 24/7.

In total, over 450 people worked in various roles across the three-year journey leading to yesterday’s breakthrough.

On a closing note, recent HS2 Ltd research unveils that the high-speed line’s arrival in the West Midlands will render a £10 billion economic lift in the coming decade, particularly concerning new development around its forthcoming stations at Birmingham’s Curzon Street and close to the city’s airport and the NEC.