A once-boring machine is boring no more. HS2’s tunnel boring machine (TBM) ‘Emily’ has completed her underground duties and was lifted from beneath Greenford on Saturday (26 July 2025), signalling a significant engineering milestone for the high-speed rail project.
Using a massive gantry crane, engineers hoisted Emily’s 9.11-metre diameter cutterhead, front and middle shield – weighing a total of 880 tonnes – from the Green Park Way site. Her subterranean journey began 3.4 miles away at Victoria Road in Ealing and concluded in June upon arrival in an underground reception chamber.
Over the course of the dig, TBM Emily excavated 775,000 tonnes of London Clay and installed 17,514 concrete tunnel segments – essential parts of the 8.4-mile Northolt Tunnel. This twin-bore tunnel will carry HS2 trains from Old Oak Common to the fringes of the capital, forming a key stretch of the route linking London and Birmingham.
As per tunnelling custom, the machine was named after a woman – in this case, Emily Sophia Taylor, who founded Perivale Maternity Hospital in 1937 and became Ealing’s first female mayor the following year.
Emily is one of four TBMs tasked with delivering the Northolt Tunnel. The fourth completed its dig earlier this month and is expected to be extracted later this summer.
