tunnel boring machine
noun1
Engineering, Natural sciences, Physical sciences A large machine used to excavate tunnels with a circular cross section.
- Near-synonym: tunneler
- Images of the first two Tunnel Boring Machines (TBMs) under construction for HS2 were released on May 26. Each TBM is 170 metres long and weighs around 2,000 tonnes. Once in use, they will run non-stop for three and a half years, stopping only for Christmas and Bank Holidays.2020 June 3, “Network News: Vote now to choose names of HS2 Tunnel Boring Machines”, in Rail, page 11: