The 2.7km Greatworth Tunnel is being built using a ‘cut and cover’ process, which involves excavating a cutting, building the tunnel and then burying it.

The tunnel structure will be made from more than five thousand giant concrete segments made at a specialist pre-cast factory in Derbyshire and then assembled on-site by EKFB, HS2’s main works contractor.

The modular approach to building the tunnel was taken instead of a traditional process of pouring the concrete on-site in order to boost efficiency and cut the amount of embedded carbon in the structure.

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. All 5,410 segments will be steel-reinforced, with the largest weighing up to 43 tonnes.

Greatworth...