The final tracks have been laid connecting the new Sydney Metro City and Southwest line with the existing North West line at Chatswood, completing a major component of the project.
Premier Dominic Perrottet said the new City and Southwest metro line would revolutionise the city's public transport network.
"This marks a major milestone in the delivery of Australia's biggest public transport project with the final tracks now laid to connect these two metro lines," Mr Perrottet said.
"Once complete, the new City and Southwest metro line will revolutionise how Sydneysiders travel by providing fast, reliable services at seven new stations under the Sydney CBD and in the city's north.
"Our long term economic plan is delivering major rail projects for the future and will support communities as they grow."
Transport Minister David Elliott said the Northern Connection now links the Sydney Metro City and Southwest line to the existing Metro North West line marking another significant construction breakthrough in this State.
"The NSW Government is delivering Australia's biggest public transport project right before our eyes," Mr Elliott said.
"Across the Sydney Metro City and Southwest, more than 5,000 people are currently employed; and 50,000 people will have worked on the project by the time it is complete."
"From 2024, passengers can travel from Tallawong in Sydney's north, into the city in under 50 minutes, Castle Hill to Barangaroo in 33 minutes and Chatswood to Martin Place in 11 minutes on a fast and reliable metro service."
Member for Willoughby Tim James said the Northern Connection is a 200-metre section of rail corridor connecting the northern suburbs to the Southwest.
"This major connection was constructed over two years with workers installing tracks and operational services in the 15.5-kilometre twin tunnels between Chatswood and Sydenham," Mr James said.
"Six teams and more than 200 workers worked around the clock over one weekend to make the final connection. It was a mammoth effort."
A rigorous testing and commissioning program along the new alignment will commence later this year, ahead of passenger services starting through the Sydney CBD in 2024.
New stations at Crows Nest, Victoria Cross, Barangaroo, Martin Place, Pitt Street and Waterloo, along with new underground platforms at Central Station will open next year.
