By rosebell
TBM Emily, which is the third of four TBMs digging the 13.5km-long Northolt Tunnel beneath London has broken through.
With the aim of arriving at Green Park Way in Greenford, west London on June 6, this machine that is operated by HS2’s London Tunnels contractor, Skanska Costain Strabag JV (SCS JV), completed a 5.5km drive.
The date of commissioning EPBM was February 2024 and by removing 775,000 tonnes of London clay and installing 17,514 tunnel segments,it has completed one bore of the eastern section of the tunnel.
It is one of four TBMs deployed on the Northolt Tunnel, two building the western section from West Ruislip and two building the eastern section from Victoria Road in North Acton.
While the plan is to lifting out all the machines that finish at Green Park Way, the final machine is expected to complete its drive later this year.
Considering the high water pressure in the ground at Green Park Way, the TBMs have to finish in a reception can in the shaft and this allows the TBM to maintain pressure while sealant can be applied from the tunnel lining, preventing water ingress. It is then depressurised before it is opened and the TBM is lifted out.
With 1,700 tonnes weight and a 9.11m diameter cutterhead, TBM Emily has been manufactured by Herrenknecht and at peak production, the TBM’s daily advance was at around 38m.
Through conveyor, the London clay extracted was taken away from Victoria Road Crossover Box, near Old Oak Common station to the London Logistics Hub at Willesden Euro Terminal and from there, it was transported by rail and reused at sites in Cambridgeshire, Kent and Warwickshire.
Also excavation of the western section of the tunnel from West Ruislip was up to two other TBMs, Sushila and Caroline and they brock through in December 2024 and April 2025, respectively.
In May the first of two TBMs boring the Bromford Tunnel broke through in Birmingham.
According to Dave Hannon, SCS JV’s project director, tunnels & routeway: “TBM Emily’s arrival at Green Park Way was a significant milestone in the HS2 program.We are now approaching completion of the Northolt Tunnel – an exciting achievement and a testament to the collaboration, dedication, and technical capabilities of our teams. With our continued focus we are pressing ahead at pace to complete the remaining works, including cross-passages, tunnel walkways, ventilation shafts, headhouses, and portals, as we deliver on part of the HS2 project.”
Following completion of the whole structure of the tunnel, the SCS JV team is due to finish building the 34 cross-passages between the two tunnel bores. Track will be laid on the tunnel invert and the shafts that provide ventilation and emergency access will be completed.
TBM Emily was named after Emily Sophia Taylor who helped establish the Perivale Maternity Hospital in 1937 before becoming Ealing’s first female mayor in 1938.
