Momentum builds as HS2 launches second giant tunnelling machine

This week we have launched ‘Cecilia’, the second of the two tunnelling machines that will excavate the ten mile long tunnels beneath the Chiltern hills. The first machine ‘Florence’ was launched just over a month ago.

The Tunnel Boring Machine (TBM) is named after pioneering astronomer and astrophysicist, Cecilia Payne-Gaposchkin, who was born in Buckinghamshire, with the name suggested by pupils at the nearby Chalfont Community College and chosen in a public vote. It will operate alongside an identical machine named ‘Florence’, with each machine excavating separate northbound and southbound tunnels and will help to safeguard the woodland and wildlife habitats above ground.

Despite starting second, Cecilia will run slightly faster, aided by geological data fed back from Florence, meaning that both machines are due to break through at around the same time.

In total there will be ten TBMs working to create 64 miles of tunnel between London and the West Midlands for the high speed rail project which is already securing jobs and helping the UK to build back better from the pandemic. More than 16,000 jobs and over 500 apprenticeships are already being supported by the project which is set to transform transport links between Britain’s major cities, free up space on the rail network for more freight and local services and support the UK’s transition to net zero carbon emissions.

The first two TBMs are operated by our main works contractor, Align – a joint venture between Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick – and launched from a site by the M25 to the north west of London. Designed specifically for the mix of chalk and flints under the Chilterns, the two identical TBMs are powered by zero carbon electricity and move at a speed of up to 15 metres a day. Each machine operates as a self-contained underground factory – digging the tunnel, lining it with concrete wall segments and grouting them into place.

Each tunnel will require 56,000 precision engineered, fibre-reinforced segments – which will all be made on site. A crew of 17 people will operate each TBM, working in shifts to keep the machines running 24/7. They will be supported by over 100 people on the surface, managing the logistics and maintaining the smooth progress of the tunnelling operation. Chalk excavated from the tunnels will be used for landscaping at the south portal site once construction is complete, creating wildlife-rich chalk grassland habitats across 127 hectares of the southern Chiltern hills.

Align is recruiting 1,200 personnel in total, including 100 apprentices, to work on the Central 1 Area of Phase One that it is delivering and are targeting their recruitment and investment to upskilling local people who are currently unemployed, with a particular focus on women, the under 25s and those with disabilities.

If you have a question about HS2 or our works, please contact our HS2 Helpdesk team on 08081 434 434 or email