Tunnel boring machine (TBM) 4 Maria is hot on TBM3 Isabelle's heels and ticking off the kilometres as they both head towards Epping. The two TBMs are each building 6 kilometres of the twin tunnels between Cherrybrook and Epping.
Maria has completed almost 4 kilometres of the job after starting work on 14 January and has just over 2 kilometres left to reach her final destination.
During her journey so far, Maria has excavated more than 288,000 tonnes of crushed rock and installed more than 12,300 concrete segments to line the tunnel. Grinding through the sandstone and shale has taken its toll and resulted in the replacement of 215 of her cutters.
Sydney Metro Northwest is the first transport infrastructure project in Australian history to use four tunnel boring machines at once.