Chartered Institute of Building Magazine of the Chartered Institute of Building


One of HS2’s largest sites set for TBM launch

3 December 2020
HS2’s Long Itchington Wood Tunnel north portal

One of HS2’s largest construction sites in the Midlands is being prepared for the launch of a tunnel boring machine (TBM) that will dig a one-mile twin bore tunnel under Long Itchington Wood, before it heads north towards Birmingham Curzon station.

The site is managed by the BBV Joint Venture (Balfour Beatty Group and Vinci Construction). There are currently 60 workers on site including student engineers and apprentices. Twenty students from Walsall College will complete their 45-day T-Level industry placement with BBV working on the delivery of HS2.

Current work on the 1km sq site entails a large and deep excavation, with 250,000m3 of material being excavated in layers before being transported and deposited locally to form environmental embankments for the main line.

The 2,000 tonne tunnel boring machine, which has been manufactured in Germany by Herrenknecht, is due for delivery on site in early 2021, will be launched in Summer 2021 and completion of the boring will be mid 2022. The tunnel will be around 9m-10m in diameter.

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.

Works on a green tunnel located south of the south portal will commence later this year using the D-Wall rigs mobilised for the reception box. Excavation of the reception box will be undertaken in this period with the material being stockpiled locally.

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.

Michael Dyke, managing director of Balfour Beatty Vinci said: “In readiness for the arrival of the first tunnel boring machine, works have already commenced in earnest to prepare the Long Itchington Wood Tunnel north portal site, with our expert team and valued supply chain partners excavating 250,000m3 of material before reusing it elsewhere across the route.

“Critical to the successful delivery of Europe’s largest infrastructure project – HS2, the 2,000 tonne tunnel boring machine will set off on its journey from the portal next summer, travelling from north to south to create the twin bore Long Itchington Wood Tunnel.”

David Bennett, HS2’s delivery director 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.”

Derbyshire-based Collins Earthworks is undertaking bulk earthmoving on the project, while SB3, a joint venture between Soletanche Bachy and Balfour Beatty Ground Engineering, are undertaking the soil nailing and shotcrete at the north portal plus the D-walls, secant piles and slurry walls at the south portal.