HS2 Ltd has launched the fifth TBM, ‘Caroline’, that will be constructing tunnels for the HS2 railway through London. The second launched in the capital, the 2,000 tonnes machine joins ‘Sushila’, that was switched on earlier this month on the same West London site.
The Herrenknecht 9.84m diameter TBM will now bore for 22 months, non-stop except for Christmas Day, towards Greenpark way in Greenford – boring 8km of the twin-bore Northolt Tunnel. ‘Caroline’ will be operated by a crew of 15 people, working in shifts.
Travelling at an average of 14m per day, ‘Caroline’ will dig the 8km tunnel and install 4,207 tunnel segment rings to create the tunnel. Each ring of the tunnel is made up of seven concrete segments which have been manufactured in the UK by Pacadar based in Kent.
‘Caroline’ will be operated by Skanska Costain STRABAG JV (SCS JV), HS2’s Main Works Civils Contractor constructing the HS2 tunnels in London. She joins ‘Sushila’ who has already travelled over 70m in the three weeks since launch.
James Richardson, Managing Director of Skanska Costain STRABAG JV said:
“We’re delighted to have begun our tunnelling journey towards Euston, travelling under one of the busiest cities in the world. Getting to this point has been a huge team effort and the scale of this programme has enabled many new people to join the industry and work on this crucial national infrastructure project.”
Once ‘Caroline’ and ‘Sushila’ reach their destination at Greenpark Way, they will be dismantled and extracted from a 40m deep shaft.
Separately, two other equally massive TBMs will set off towards Greenpark Way from HS2’s Victoria Road site in 2023 to build a further 5.4km twin-bore tunnel. Combined, the quartet of TBMs will build 13.4km of twin bored tunnels between West Ruislip and the new high speed rail super hub station at Old Oak Common.
Another tunnel 7.2km twin-bore tunnel extending from Old Oak Common to Euston will complete HS2’s journey to its London terminus.
Spoil from the tunnels at West Ruislip will not travel far as it will be used for sustainable placement to the North, creating embankments for the new railway, as well as new environmental habitats. It will also be used to remodel the West Ruislip golf course which is closed during HS2 construction.