The two tunnel boring machines (TBMs) digging HS2’s longest tunnels have passed Amersham shaft on their 10 mile drive under the Chilterns.
‘Florence’ and ‘Cecilia’ have spent almost two years excavating the twin tunnels and are now 5.5 miles into their journey, having reached the halfway point last month.
While digging, each machine is also lining its tunnel with 56,000 concrete segments and grouting them into place as it moves forward.
Meanwhile, engineers have also excavated five shafts that will provide ventilation and emergency access near Chalfont St Peter, Chalfont St Giles, Amersham, Little Missenden and Chesham Road.
The 44-metre deep shaft at Amersham is situated in the middle of a road junction just outside of Buckinghamshire town.
The two TBMs are operated by Align – a joint venture formed of Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick.
“Florence and Cecilia reaching our third shaft at Amersham is a great achievement for not only the tunnelling team and the team involved in excavating and preparing the shaft, but also the supporting teams on the surface at the South Portal, manufacturing the concrete segments required to line the tunnel and processing the spoil from the tunnels.”
