Tunnel boring machine (TBM) Mum Shirl has broken through a wall of rock into the new Martin Place Station in the heart of Sydney.
Mum Shirl has excavated about 650,000 tonnes of rock – enough to fill about 100 Olympic swimming pools - since starting work at Marrickville in November last year.
The Martin Place Station cavern took about 21 months to excavate using roadheader tunnelling machines.
About 198,000 tonnes of rock – enough to fill about 30 Olympic swimming pools - was removed to build the massive cavern under the CBD, which is supported by 5,532 tonnes of steel and 85,139 tonnes of concrete.
TBM Mum Shirl and TBM Nancy, which arrived at Martin Place earlier in October, are two of the five TBMs carving out the 15.5 kilometre twin tunnels between Chatswood and Sydenham.
Mum Shirl is delivering a 8.1 kilometre fully lined and waterproof tunnel which runs from Marrickville through new stations at Waterloo, Central Station, Pitt Street, Martin Place and Barangaroo.
Both borers will undergo maintenance at Martin Place to prepare for the final 1.3 kilometre leg to Barangaroo.
The TBM is named after Mum Shirl who was a prominent and widely respected Wiradjuri woman, social worker and humanitarian activist committed to justice and welfare of Aboriginal Australians.