On Sunday 25th May, engineers working on the HS2 project lifted the TBM's 9.48 metre diameter cutterhead, front and middle shield, weighing 850 tonnes, using a large gantry crane. The tunnelling machine concluded its 5-mile journey from West Ruislip in April, arriving in an underground reception chamber. TBM Caroline excavated over 1.2 million tonnes of earth and installed 4,217 tunnel rings.

TBM Caroline, named by a local school after the astronomer Caroline Herschel, was used to construct the western section of the Northolt tunnel - a 13.52 km (8.4-mile) tunnel being built by four TBMs which will take HS2 trains from Old Oak Common Station to the outskirts of the capital. The first machine to arrive at Green Park Way, named Sushila, was removed in March this year. 

For further information click here and uk/65 for THE tunnelbuilder archive. Visit https://www.hs2.org.uk/. 22/25.