‘Caroline’ has begun her journey from West Ruislip to Greenford as the second giant tunnel boring machine under London to begin tunnelling this month
Named after the first professional female astronomer Caroline Herschel, the giant tunnel boring machine under London is constructing tunnels for the HS2 railway through the capital.
The giant machine will now dig for 22 months, non-stop except for Christmas Day, towards Greenpark way in Greenford – boring five miles of the twin-bore Northolt Tunnel.
‘Caroline’ will be operated by a crew of 15 people, working in shifts. An additional 25 people will directly support each tunnel drive on the surface.
Travelling at an average of 14m per day, ‘Caroline’ will dig the five-mile 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.
The machine was switched on by HS2’s civils delivery director, Mike Lyons.
Displaced soil will be used to create biodiversity spaces in the local areas
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.
It is estimated that 2 million cubic metres of excavated material will be removed, weighing 2.46m tonnes over the TBM project.
The machines are named after both historical female figures and local heroes
‘Caroline’ will be operated by Skanska Costain STRABAG JV (SCS JV), HS2’s main works civils contractor constructing the HS2 tunnels in London.
TBM Sushila, which began her journey earlier this month and has already travelled over 70m, was named after local schoolteacher Sushila Hirani, head of department and lead for STEM at Greenford High School. The Willow class at Dairy Meadow Primary School in Southall suggested the name due to her inspiring work and passion for getting more women and young people from BAME backgrounds into STEM subjects.
German-born British astronomer Caroline Herschel was considered the first professional female astronomer. In her career she discovered three new nebulae and was the first woman to ever discover a comet in 1786. She compiled a catalogue of 2500 nebulae and, in 1828, the Royal Astronomical Society awarded her its gold medal for this work.
The giant tunnel boring machine under London are the latest parts of the HS2 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 tunnel boring machines will set off towards Greenpark Way from HS2’s Victoria Road site in 2023 to build a further 3.4mile twin-bore tunnel.
Combined, the quartet of TBMs will build 8.4miles of twin bored tunnels between West Ruislip and the new high speed rail super hub station at Old Oak Common.
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.”
