Humongous Tunnel Boring Machines
tbm tunnel boring Machine, Alptransit tunnel train switzerland.
tbm Tunnel boring Machine
What dwells beneath, does not dwell so quietly - these enormous machines are notorious for producing shaking and loud noise, but they do the job - excavating tunnels wide enough to fit two trains inside (maximum tunnel diameter 19 meters). They produce a smooth tunnel wall, but woe to any creature that stands in its way (obviously).
Science Experiments: Humongous Tunnel Boring Machines