Work on a temporary factory that will build wall sections for the 10-mile Chiltern HS2 tunnel is being carried out.

The tunnel precast factory at the south portal site next to the M25 will allow HS2 contractors to cast all tunnel segments on site to avoid putting extra HGVs onto the roads and causing more congestion for residents.

Two giant tunnelling machines - named Florence and Cecilia - are due to launch from the site next year.

The 170 metre long, 2,200 tonne machines will spend more than three years underground and use 112,000 concrete segments to line the tunnels under the Chilterns, moving at a speed of 15.6m a day.


A second precast plant will be used to cast sections for the nearby Colne Valley Viaduct.

Once work is complete, the pre-cast plants will be taken down and HS2 say the whole site will be landscaped with excavated material and trees will be planted.

Cauton Engineering in Nottinghamshire delivered all 2,400 tonnes of the steelwork to the site to build the factory.

HS2 Ltd’s C1 Senior Project Manager, Mark Clapp said: “The pre-cast plant will play a crucial role in delivering the Chiltern tunnels. By casting all 112,000 segments on site, we can significantly reduce the number of HGVs on local roads, reducing disruption for the local community."