Greatworth Green Tunnel

The Greatworth Green Tunnel is the longest green tunnel on the HS2 route and will stretch for 1.7 miles (2.7km) through West Northamptonshire. It is one of five green tunnels, which are shallower tunnels that will be finished with trees, plants, and shrubs on top – helping them blend into the natural landscape that are being built. Materials from the excavation are kept on site and then reused on the tunnel surroundings, reducing movement of spoil.

Tunnel construction

Unlike a bored tunnel, the tunnel is being built using a ‘cut and 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.

Applying lessons from the construction of the latest French high-speed lines, the tunnel will be made from more than five thousand giant concrete segments made at a specialist pre-cast factory in Derbyshire and assembled on site. This is more efficient and reduces the amount of embedded carbon in the structure than the traditional process of pouring concrete on site.

Landscaping design plans

Greatworth Green Tunnel is designed to blend the high-speed railway into the rural landscape and reduce disruption for communities around Greatworth in West Northamptonshire.

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.

Tailored landscaping design plans are also being developed, with thousands of native trees and shrubs typical to the local area – such as Silver Birch, Oak, Beech and Willow – planted to create new woodland areas around the portals and recreate the hedgerows and field boundaries on top of the tunnel.

HS2 green corridor