The HS2 tunnel boring machine (TBM) ‘Florence’ has passed the one mile mark this week, cutting through a mix of chalk and flint beneath the Chiltern hills just outside London.

Within the Chiltern tunnels looking south towards London

© HS2

Launched in May, the 170-metre long TBM is one of two identical machines excavating twin ten-mile-long tunnels. The second machine, ‘Cecilia’, is a short way behind, with both expected to break out in approximately three years’ time.

Designed specifically for the geology of the Chilterns, each machine is a self-contained underground factory, digging the tunnel, lining it with concrete wall segments and grouting them into place as it moves forward.

The TBMs are operated by HS2’s main works contractor Align – a joint venture formed of Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick.

A crew of 17 people keep the machines running, working in shifts and supported by over 100 people on the surface, managing the logistics and maintaining the smooth progress of the tunnelling operation.

source= https://railway-news.com/hs2-tunnel-boring-machine-completes-first-mile-under-the-chilterns/