HS2 tunnelling starts in the Chilterns

The first of 10 Tunnel Boring Machines started work on High Speed 2’s Chiltern Tunnel on 13 May, with High Speed 2 Minister Andrew Stephenson and HS2 Chief Executive Mark Thurston marking the occasion.

Named Florence after nurse Florence Nightingale who lived at nearby Claydon House, the machine will excavate and line 10 miles of tunnels under the Chilterns over the next three years.

Florence is one of two TBMs built by Herrenknecht which will work on the Chiltern tunnels. They will be operated by main works contractor Align – a joint venture formed of Bouygues Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick. The other TBM is named after pioneering astronomer and astrophysicist Cecelia Payne-Gaposchkin

Each machine will dig the tunnel, line it with concrete segments and grout them into place at a rate of 15 metres per day. Each bore will require 56,000 fibre-reinforced segments which are being made on site.

The machines require a crew of 17 working in shifts around the clock, supported by a team of more than 100 people on the surface. Chalk excavated from the tunnels will be used for landscaping at the south portal site when construction is complete.