A launchpad is being constructed for a tunnel boring machine (TBM) that will dig a one-mile twin bore tunnel under Long Itchington Wood, before the route heads north and swings into Birmingham’s Curzon Street Station.
Current work on the one-square-kilometre north portal site entails a large and deep excavation, with 250,000 cubic metres of material being excavated in layers before being transported and deposited locally to form railway embankments.
Collins Earthworks is doing the bulk earthmoving.
SB3, a joint venture of Soletanche Bachy and Balfour Beatty Ground Engineering, is doing the soil nailing and shotcrete at the north portal plus the D-walls, secant piles and slurry walls at the south portal.
The 2,000-tonne Herrenknecht TBM is due for delivery on site in early 2021 for a summer launch at the north portal, with completion of the boring scheduled for mid-2022.
The TBM will take around five months to complete the first bore of the twin bore tunnel. Once the first bore is complete, the TBM will be extracted at the south portal reception box before being transported by road back to the north portal to commence the second bore. A large portion of the TBM support modules will be drawn back through the bored tunnel before being positioned on the cradle for the second bore.
On this stretch of the route there are two tunnels being built by BBV – the other one is Bromford Tunnel. There are also 100 bridges, 35 viaducts, 36 cuttings and 70 bridge structures on this part of the route.
HS2 delivery director David Bennett said: “The Long Itchington Wood Tunnel north portal site is a key site on the Midlands section of the HS2 route, and it’s great to see work progressing well in preparation for the arrival of the tunnel boring machine next year.
“The tunnel in this location goes under Long Itchington Wood specifically to preserve a section of ancient woodland. This forms a key element in how we are managing environmental impacts through the design of the railway. Along with 32 miles of tunnel, HS2 will also be criss-crossed by over 150 bridges and underpasses on Phase One, including 16 specially designed ‘green bridges’ covered in planting, and a green corridor alongside the route will integrate HS2 into the landscape.”