Sydney Metro tunnelling was completed under the city centre, breaking through a wall of rock at the new Barangaroo Station. At the site of the new Barangaroo Station, it took about two years to excavate about 460,000 tonnes of rock for the new station.
Now four out of five mega tunnel boring machines have finished the work, with the remaining tunneling works will be performed for the second metro railway tunnel deep under Sydney Harbour.
Since starting work at Marrickville in November 2018, the TBM Mum Shirl took about 14 months to build an 8.1-km tunnel to Barangaroo, cutting through sandstone and shale to excavate more than 821,000 tonnes of rock.
About 29.5 km of 31 km of twin metro tunnels between Chatswood and Sydenham, or 97 per cent, are now complete with TBM Kathleen currently digging under Sydney Harbour to finish her second under-harbour metro tunnel.
TBMs Nancy, Wendy and Mabel finished work late last year.