The fourth, and final, Tunnel Boring Machine (TBM) for HS2’s 13.5km Northolt tunnel beneath London, has now been launched.
TBM Anne, an Earth Pressure Balance Machine (EPBM) manufactured by Herrenknecht AG, weighs in at 1,700 tonnes and is 170m long with a 9.11m diameter cutterhead. This impressive machine was lowered in parts into the 25m deep crossover box at the end of last year and will now bore 5.5km from Victoria Road in Ealing, near HS2’s Old Oak Common station, to Greenpark Way in Greenford, alongside TBM Emily which was launched in February.
As it progresses, TBM Anne will install concrete tunnel rings with an external diameter of 8.78m and an internal diameter of 8.10m, each made up of seven segments weighing approximately 7 tonnes. The ring segments are manufactured in Hartlepool and transported to London by train, following the reopening of a freight line at the town’s Dock.
TBM Anne is the eighth TBM to be launched across the HS2 project with almost half of the 105km of twin-bored tunnels has now having been excavated. London tunnels contractor, Skanska Costain STRABAG Joint Venture, delivered an extensive programme of work in order for the TBM to launch at the Victoria Road Crossover Box, excavating the caterpillar-shaped box where eventually the trains will cross tracks on their way in and out of Old Oak Common station.
The other 8km of the twin-bored Northolt tunnel has been under construction since 2022, with TBMs Sushila and Caroline both over halfway through their journey between West Ruislip, on the outskirts of London, and Greenpark Way. The four TBMs are all set to complete their journeys in 2025.
