HS2 has begun assembling the project’s longest ‘green tunnel’ - designed to blend the high speed railway into the rural landscape and reduce disruption for communities around Greatworth in West Northamptonshire.  

The 2.7km tunnel is being built using a cut & cover process. This involves excavating a cutting, building the tunnel and then burying it, with trees, shrubs and hedgerows planted on top to blend in with the surrounding countryside.  

The tunnel structure will be made from 5,410 steel reinforced concrete segments with the largest weighing up to 43 t, made by Stanton Precast in Ilkeston, Derbyshire. The segment will be assembled on site by HS2’s main works contractor, EKFB - a team made up of Eiffage, Kier, Ferrovial Construction and BAM Nuttall.  

Applying lessons from the construction of the latest French high-speed lines, EKFB opted for this modular approach - instead of a traditional process of pouring the concrete on site - to boost efficiency and cut the amount of embedded carbon in the structure.  

Greatworth is one of five ‘green tunnels’ that are being built on phase one of the HS2 project, which is designed to improve links between London, Birmingham and the north, boost the economy and free up more space on the existing rail network for freight and local services.  

Designed as an m-shaped double arch, the tunnel will have separate halves for southbound and northbound trains. Five different concrete precast segments will be slotted together to achieve the double arch which is the height of two double-decker buses - one central pier, two side walls and two roof slabs.  

The tunnel will be built in sections, with construction of the main structure expected to take around two years. Local roads such as the B4525, Sulgrave Road, Helmsdon Road and access for Greatworth Park will be realigned to cross the tunnel, as well as local footpaths.  

Shorter green tunnels are also being built at Wendover in Buckinghamshire, Burton Green in Warwickshire and in the London Borough of Hillingdon. All the tunnels will have specially designed ‘porous portals’ at either end to reduce the noise of trains entering and exiting the tunnel, along with small portal buildings to house safety and electrical equipment.  

For further information click here and uk/65 for tunnelbuilder archive and visit https://www.hs2.org.uk/. 39/23.