Construction on Britain’s new high-speed railway, HS2, has passed a significant milestone with the completion of the 8.4-mile Northolt Tunnel. The final tunnel boring machine, named Anne, broke through into a shaft at Green Park Way in Greenford on Thursday, completing excavation of the twin-bore tunnel that will connect West Ruislip to the forthcoming Old Oak Common station.
The machine, named Anne after educational reformer Lady Anne Byron, installed the final concrete ring before surfacing into a vent shaft at Green Park Way. The journey concludes the tunnel dig between West Ruislip and the new Old Oak Common super-hub station, making Northolt the second-longest tunnel on the HS2 route, after the Chiltern Tunnel.
Alan Morris, HS2 Ltd’s construction delivery director, said: “Completing the excavation of this 8.4 mile-long tunnel on HS2 is a real achievement and one the team should be immensely proud of. We’re building HS2 for the future, to increase capacity on our rail network and improve journeys for millions of rail users.”
TBM Anne, launched in April 2024, spent 14 months underground with 48-person teams working around the clock. The four machines involved in the Northolt dig, supplied by Herrenknecht AG, excavated over 4.1 million tonnes of London clay and installed 14,300 concrete rings using segments produced in Hartlepool.
Richard Adam of SCS JV, the contractor delivering the tunnel, described Anne’s completion as “a major milestone” that was delivered “safely and on schedule”.
Work will now turn to tunnel fit-out, 34 cross passages and five surface headhouses. Meanwhile, two more TBMs are being prepared for launch toward Euston next year.
