On 27 October 2022 HS2 Ltd launched their fifth TBM Caroline, that will be constructing tunnels for the HS2 railway through London. HS2’s first London TBM Sushila - started on the 06 October on the same West Ruislip site in West London – and has already travelled over 70m.  

Named after 18th century astronomer Caroline Herschel, the TBM will now dig for 22 months, non-stop except for Christmas Day, towards Greenpark way in Greenford – boring 8.05 km (5 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 tunnel and install 4,207 rings (weighting 8.5 t) composed of 7 concrete segments which have been manufactured in the UK by Pacadar based in Kent.  

TBM Caroline will be operated by Skanska Costain Strabag Joint Venture (SCS JV), HS2’s Main Works Civils Contractor constructing the HS2 tunnels in London.    

Once TBMs Caroline and Sushila (140 m in length, 2,050 t in weight and 9.84m in diameter) 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 5.47 km (3.4mile) twin-bore tunnel. Combined, the quartet of TBMs will build 13.52 km (8.4miles) of twin bored tunnels between West Ruislip and the new high speed rail super hub station at Old Oak Common.  For further information please use the tunnelbuilder archive click here and uk/65. Visit https://www.hs2.org.uk/.  43/22.