The first of 112,000 walls segments for the Chiltern tunnel were produced at a purpose-built production line at the project’s tunnelling HQ close to the M25 in preparation for the launch of HS2’s first giant tunnelling machines.
The project’s first two Tunnel Boring Machines (TBMs) – named Florence and Cecilia – are due to launch in early summer. Each of the 170m long, 2,000 tonne machines will spend more than three years underground, digging and slotting the wall segments into place to create the 10-mile long tunnels.
Made of high-performance fibre-reinforced concrete, the segments are being produced at a temporary pre-cast factory next to the TBM launch pads at what will be the south portal of the tunnels. This will avoid putting extra lorries on local roads and ensure a steady supply of segments for the TBMs.
Construction of the Chiltern Tunnel, and nearby Colne Valley Viaduct, is being led by HS2’s main works contractor and HSRG member Align JV – a joint venture made up of three companies: Bouygues Travaux Publics, Sir Robert McAlpine, and VolkerFitzpatrick. Work on the two structures will support around 1,200 jobs.
Once construction is complete, the pre-cast factory and the rest of the south portal site, will be cleared, with the chalk excavated from the tunnels used to landscape the site and create high quality chalk grassland and other wildlife habitats.