HS2 Warwickshire site now ready for TBM launch
26 February 2021Completion of site excavation at HS2’s north portal at Long Itchington Wood Tunnel, Warwickshire means the site is ready for the launch of the tunnel boring machine (TBM).
Germany-based Herrenknecht has been sending the 10.26m-diameter machine to site in pieces, ready to be assembled to start mining the first bore in summer 2021. Once the machine reaches the south portal after one mile and an anticipated five months of tunnelling, it will be extracted and transported by road back to the north portal to start the second bore.
Unique on the HS2 Phase 1 route, the tunnel at Long Itchington Wood uses two tunnelling construction methods, mainly TBM-bored but also a short section of cut-and-cover.
More than 300,000m3 of topsoil and subsoil have been excavated in the process of preparing the north portal launch site. The various layers have been stored and separated by a layer of straw to allow correct reinstatement once the tunnel has been built.
Site excavation was performed by Midlands-based Collins Earthworks which, since April 2020, has employed 120 people and a 35-strong construction fleet boasting state-of-the-art, fuel-efficient engines. The Midlands-based firm is contracted to HS2’s main works contractor BBV Joint Venture (Balfour Beatty Group and Vinci Construction) which is responsible for constructing the northern section of HS2 as it runs into Birmingham.
Aiden Goggins, BBV’s Construction Director at the Long Itchington Wood Tunnel site said:
“The Long Itchington Wood Tunnel site is one of the project’s largest, and Collins Earthworks have worked for nearly a year to carefully excavate material which will be reused to form environmental embankments and landscape for the railway. The tunnel in this location preserves the ancient woodland, so forms a key element in how we are managing environmental impacts through the design of the railway.”
In total, HS2 will have 64 miles of tunnelling spread across nine tunnels of 9.1m internal diameter. At the peak of construction on the whole of Phase One, ten TBMs will work 24hrs/day, 7 days/week. The machines will bore and line the tunnels as they drive forward at speeds of up to 15m/day.
