HS2’s Giant Tunnelling Machines Smash First Stage Under Chilterns
HS2 has announced a major milestone as its colossal 2,000-tonne Tunnel Boring Machines (TBMs) complete the initial phase of the Chilterns tunnel work. Together, the two machines have carved out over 3.6 miles of underground tunnels, reaching the first ventilation shaft at Chalfont St Peter.
Ventilation Shaft at Chalfont St Peter Takes Shape
The ventilation shaft, plunged 78 metres deep, will be one of five emergency access points and ventilation hubs for the twin tunnels. Designed to blend into the local countryside, its headhouse will resemble typical farm buildings, softening the visual impact on the area.
HS2’s Longest Tunnel to Protect Woodlands and Wildlife
“The Chiltern tunnel will run deep beneath the hills to safeguard woodlands and wildlife habitats above ground,” said David Emms, HS2 Ltd Project Client. “This approach significantly reduces disruption for local communities during the construction and operation of the new railway. I’m proud of the progress made by our teams, particularly in excavating the five ventilation shafts, and I’d like to thank everyone involved in reaching this point.”
Experts Behind the Scenes: Align JV and TBM Operators
The TBMs are run by Align, a joint venture featuring Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick. Each machine is controlled by a dedicated team of 17 specialists, supported by over 100 personnel working above ground.
Daniel Altier, Align Project Director, commented on the achievement:
“Reaching the Chalfont St Peter ventilation shaft is a huge win for both our tunnelling and construction teams. Special thanks go to our supply chain partners KVJV and Keltbray who have worked tirelessly over recent months.”
Precision Engineering on a Massive Scale
The project demands 56,000 fibre-reinforced concrete wall segments for each of the northbound and southbound tunnels. These precision-engineered segments are produced in state-of-the-art factories located at the south portal, just inside the M25, ensuring quality and efficiency as tunnelling progresses.
