The 8.4-mile Northolt Tunnel tunnel, which will run from Victoria Road in Ealing to West Ruislip in Hillingdon, is being constructed by four tunnel boring machines (TBMs).
In keeping with tunnelling tradition, the fourth machine is named after a prominent woman – in this case, Lady Anne Byron (1792-1860), an educational reformer and philanthropist.
TBM Anne will bore 3.4 miles from Victoria Road in Ealing, near HS2’s Old Oak Common station, to Greenpark Way in Greenford, alongside TBM Emily, launched in February.
The other five miles of twin-bored tunnels has been under construction since 2022, with TBMs Sushila and Caroline both more than halfway through their journey between West Ruislip and Greenpark Way. The four TBMs are all set to complete their journeys in 2025, when they will be extracted from the ground through shafts at Greenpark Way.
HS2’s London tunnels contractor, Skanska Costain Strabag (SCS) joint venture, launched TBM Anne at the Victoria Road crossover box, where eventually the trains will cross tracks on their way in and out of Old Oak Common station.
Anne is the eighth TBM that has been launched to date across the entire London-Birmingham project and almost half of the 65 miles of twin-bored tunnels planned for the project has now been excavated.
The TBM is one of 10 machines specially designed by Herrenknecht for HS2 and the ground through which they will bore. Two remaining TBMs, which will eventually be used to dig HS2’s final tunnel between Old Oak Common and Euston, in central London, are still being built.
SCS JV worked with Herrenknecht on a cutting edge design that maximises productivity and achieves the highest standards in a tunnelling environment. TBM Anne, an earth pressure balance machine, weighs 1,700 tonnes and is 170 metres long. The cutterhead is 9.11 metres in diameter. She was lowered in parts into the 25-metre deep crossover box at the end of last year, where she was re-assembled and prepared for launch.
Malcolm Codling, HS2’s project client director for the London tunnels, said: “HS2 has reached peak tunnelling activity as we focus on delivering the HS2 route between London and Birmingham. The launch of Anne is the culmination of many years of work for the London Tunnels team and a further triumph in British engineering.”
For the Northolt Tunnel East, the tunnel drive being completed by TBM Anne, the concrete tunnel ring segments are being cast by Strabag in a new factory in Hartlepool, 260 miles away.
SCS managing director James Richardson said: “The launch of TBM Anne is a milestone moment in this year of peak activity for the HS2 London tunnels project. With a quartet of TBMs and over 20 construction sites all making significant progress, we are on course to deliver the high-speed line into central London, creating economic growth and opportunities at every step of the way.”
The two final TBMs for the Euston tunnels, taking HS2 trains from Old Oak Common into central London, are set to be delivered to the UK later this year and lowered into the underground station box at Old Oak Common ready for launch.
Work is continuing with the preparations for the railway between Old Oak Common and Euston despite the government having put plans for a Euston terminus on hold last year, pending new funding arrangements. The government is hoping to get private developers to pay for the new Euston station.
Got a story? Email news@theconstructionindex.co.uk
