The main cavern for the new train station under the State Library is now complete, which means there’s currently a 240-metre-long, 30-metre-wide void 36 metres under Swanston Street.

The new station is one of five being built as part of Melbourne’s $11 billion Metro Tunnel Project, which is so far on track to be completed by 2025.

Victorian Premier Daniel Andrews visited the subterranean construction site last week, along with the state’s transport minister, Jacinta Allan.

“While our city keeps moving, people are hard at work below the ground building the Metro Tunnel,” Andrews said in a statement.

“A huge amount of work continues to be done at State Library Station, with the platform already taking shape.”

Three road headers – excavation machines designed to smash through rock, each weighing some 118 tonnes – have been working under the city for more than a year digging out up to 500 tonnes of rock each day. (A Melbourne tram weighs up to 50 tonnes, and these machines are at least five metres shorter.)

The permanent station is now being built and the concrete floor has been laid.

The new State Library station will be located under Swanston Street between La Trobe and Franklin streets, and its 19-metre platforms will be some of the widest metro platforms in the world.

It will also be connected to Melbourne Central station so commuters can switch between Metro Tunnel and City Loop trains.

The five new Metro Tunnel underground stations – which were named after a public vote – are Arden (in North Melbourne), Parkville, Anzac (near the Shrine of Remembrance), and State Library and Town Hall (in the CBD).