AI-powered tunneling machines Betty and Dorothy retired after finishing Sydney Metro West, with parts recycled.

Tunnel boring machines Betty and Dorothy, the first in Australia to use AI-assisted steering, have been retired after completing work on Sydney Metro West, with their worn steel parts recycled. Operating 24/5, they excavated 800 meters monthly and installed over 57,900 concrete segments. Named after Australian icons Dorothy Buckland-Fuller and Betty Cuthbert, they were part of a fleet including newer machines Jessie and Ruby, which used slurry systems to navigate tough conditions under Sydney Harbour and the CBD, moving 460,000 tonnes of rock at 90 meters per week. All six machines cost tens of millions to build. Jessie is nearing completion, followed by a complex retrieval in the CBD.