HS2 Launches Second Giant Tunnelling Machine – Cecilia

This week HS2 has launched Cecilia, the second of two 2,000t tunnelling machines that will excavate the ten-mile-long tunnels beneath the Chiltern Hills.

The tunnel boring machine (TBM) was named after the pioneering astronomer and astrophysicist Cecilia Payne-Gaposchkin by public vote.

TBM Cecilia from the air
TBM Cecilia from the air

It will operate alongside an identical machine – named Florence – which was launched just over a month ago. Each machine will excavate separate northbound and southbound tunnels, helping to safeguard the woodland and wildlife habitats above ground.

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

In total there will be ten tunnel boring machines (TBMs) working to create 64 miles of tunnel between London and the West Midlands for the high-speed rail project.

The first two TBMs are operated by HS2’s main works contractor, Align – a joint venture formed of 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, Florence and Cecelia are powered by zero carbon electricity and move at a speed of up to 15m 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.

Daniel Altier, Align Project Director, said:

“We are delighted to be launching Cecilia this week, the second of our TBMs, to dig the Chiltern tunnels.

“Both TBMs are identical and include innovations to improve efficiency and the safety of the environment in which the crews will be working that have never before been introduced on any previous TBM, worldwide.”

Align is recruiting 1,200 personnel in total, including 100 apprentices, to work on the Central 1 Area of HS2 Phase One that it is delivering. It is targeting its recruitment and investment in upskilling local people who are currently unemployed, with a particular focus on women, the under 25s and those with disabilities.

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