HS2 launches third TBM in London

TBM Emily, named after Emily Sophia Taylor who helped establish the Perivale Maternity Hospital in 1937 before becoming Ealing’s first female mayor in 1938, will dig almost half of the 13.5km Northolt Tunnel.

It will bore 5.5km under Ealing from Victoria Road Crossover Box, near HS2’s new Old Oak Common station, to Greenpark Way in Greenford.

The Herrenknecht EPBM. designed for the soft London clay it will encounter, weighs 1,700 tonnes and has a 9.11m diameter cutterhead.

HS2 client director Malcolm Codling said the preparation to launch TBM Emily had been complex but the project remained on schedule to complete the Northolt Tunnel in 2025.

The Northolt Tunnel will carry HS2 trains in and out of London – extending between the new Old Oak Common superhub and the outskirts of the capital at West Ruislip.

The twin-bore tunnel is being built in two sections. Two TBMs, named Sushila and Caroline, are already constructing it eastward between West Ruislip and Greenford. Another two – Emily and Anne – are being used to dig the tunnel in the opposite direction from Victoria Road Crossover Box to Greenford.  

Emily and Anne’s tunnel drive will cover 5.5km of the tunnel in total – slightly less than those being used on the other section. Emily was launched yesterday and Anne – the fourth and final Northolt TBM – will launch next month.

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.

The London clay extracted to build the tunnel will be removed from Victoria Road Crossover Box by conveyor, and taken to the London Logistics Hub at Willesden Euro Terminal. From there, it will be taken by rail and reused at sites in Cambridgeshire, Kent and Rugby.

HS2 is also making progress on preparations on the separate tunnel between Old Oak Common and Euston – the line’s ultimate central London terminus – following the breakthrough on the Atlas Road Logistics Tunnel in January. The logistics tunnel runs from the Old Oak Common Station box to Atlas Road logistics site and will facilitate the tunnelling operation to construct the Euston Tunnel.

Two further TBMs will be delivered to Old Oak Common later this year and stored in the underground box until the government gives the go-ahead for the Euston Tunnel. Following the government’s Network North announcement in October last year, the funding and delivery arrangements for the Euston Tunnel are being reviewed.