HS2 main works contractor EKFB (Eiffage, Kier, Ferrovial and BAM Nuttall) has developed an offsite approach to build a new ‘green tunnel’ for the high-speed rail line.
EKFB will build the 1.5-mile Chipping Warden tunnel in Northamptonshire from 5,000 concrete segments manufactured offsite in Derbyshire.
The tunnel will take the form of an M-shaped double arch, with separate halves for southbound and northbound trains.
Carbon saving
EKFB will slot five different precast segments together to build the double arch. Each arch will consist of one central pier, two side walls, and two roof slabs. All 5,020 segments will be steel reinforced.
The design means the tunnel will be lighter than traditional alternatives, halving the amount of carbon embedded in the structure.
EKFB’s project manager, Jeremie Martin, said: “Seeing the first set of precast units being installed is a milestone that the whole team is very proud of. This three-year construction programme will benefit from offsite manufacturing, making the green tunnel build more efficient than the traditional onsite building method.
“The HS2 green tunnels are a first of a kind in the UK. We have designed them as a twin arch ‘M’ shape which is more efficient than the standard box structure, reducing the amount of concrete required. It is a great example of how innovative engineering design can reduce carbon impact.”
EKFB is due to complete the tunnel in 2024.
HS2 plans similar tunnels at nearby Greatworth, as well as Wendover in Buckinghamshire and Burton Green in Warwickshire.
