German construction equipment manufacturer Herrenknecht has secured a contract to supply the first two tunnel boring machines (TBMs) for London’s HS2 tunnels.
Skanska Costain STRABAG JV (SCS JV), the main works civils contractor of HS2, has signed the contract to proceed on the southern stretch of HS2 high-speed rail project.
Herrenknecht will design and manufacture the TBMs specifically for the London clay and chalk ground conditions they will bore through.
HS2 said that the tunnels are twin bored, and will be 21km each way, between central London and the M25 motorway.
The tunnels start just outside of Euston station and will be under the ground until they emerge in West London at Old Oak Common station. They will continue underground from Old Oak Common to the outskirts of West London.
In total, 10 TBMs will be purchased to build the 103km of the tunnel along the HS2 route between the West Midlands and London.
HS2 said that the first two TBMs will be inaugurated from a portal at West Ruislip and will travel about 8kms east, creating the western section of the Northolt Tunnel.
After arriving at Green Park Way in Greenford these machines will be lifted out from the ground and the site will be utilised as a vent shaft.
The 13.5km long tunnel will be completed with a 5.5km tunnel drive from Old Oak Common using two other TBMs that are yet to be procured.
The remaining 7.2km London tunnel between the two HS2 stations will be completed by the second tunnel between Euston and Old Oak Common.
Once the first new TBMs are built, they will be transported by sea and delivered at the site at the end of 2021.
Upon assembling, the TBMs are estimated to commence the tunnel drive in mid-2022, with completion at the beginning of 2024.
Tunnel Boring Machine Florence at the Herrenknect factory. (Credit: High Speed Two Ltd.)