Cecilia, the second 2000 t TBM, reached northern portal of 16.09 km (10 mile) high-speed rail tunnel under Chiltern Hills completing a journey that began in June 2021: click here for the video.

Cecilia joined its twin sister machine, Florence, arrived at the site near the Buckinghamshire town of Wendover on 27 February, after completing her adjacent tunnel drive. 

The two 2,000 t machines have built the twin bore tunnel at depths of up to 80 m and excavated three million cubic metres of chalk. Each machine operates like an underground factory, able to excavate the tunnels and line them with 56,000 pre-cast concrete tunnel segments, grouting them into place and moving forward at an average speed of 16 m per day. 

When HS2 is operational trains will travel through the Chiltern tunnel – the line’s longest – at speeds of up to 200mph, helping to almost halve journey times between Britain’s two largest cities.

The new high-speed line will relieve traffic the West Coast Mainline, freeing up space for more local services on the most crowded part of the important Victorian route. It will almost double rail capacity between London and the West Midlands, providing a more reliable service and driving economic growth. 

Both machines launched from the tunnel’s south portal, near the M25 motorway, were operated by HS2’s main works contractor, Align – a joint venture formed of three international infrastructure companies: Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick. The machines are made in Germany by TBM specialists Herrenknecht.

For further information please click here for the breakthrough of the first tube, here and uk/65 for the tunnelbuilder archive. Visit https://www.hs2.org.uk/. 12/24.