Victoria's Labor government has pledged to build a $50 billion underground rail loop connecting Melbourne's major train lines, a transport project it says will be the biggest in Australian history.
Premier Daniel Andrews made the announcement on his Facebook page on Tuesday, ahead of the state election due in November.
The Suburban Rail Loop will connect the major rail lines to a number of suburbs, including Clayton, Glen Waverley, Doncaster and Box Hill, and also link up to Tullamarine airport.
"It's the biggest transport project in Australian history," the government-produced video posted by Mr Andrews says.
It would cost $50 billion and construction would start in 2022.
Mr Andrews told Triple M radio $300 million would be set aside in next year's budget if Labor won the November state election.
About 400,000 passengers are expected to use the underground loop each day once, the state government estimates.