A long-awaited rail link to Melbourne airport is edging closer to reality, after the prime minister and Victorian premier pledged $10 billion in funding for the project.
Scott Morrison and Daniel Andrews signed a Heads of Agreement, setting out key terms of the project in Melbourne on Wednesday.
Construction on the rail link would start in 2022 and is expected to take nine years to complete.
"This is a big deal, and it's an inked deal now between the Victorian and Commonwealth governments," Mr Morrison said.
The project was game changing and would help ease congestion in Melbourne, while also benefiting international visitors.
"This will also be a very important choice for international travellers ... a rail option is critically important for them," he said.
"It's long overdue."
The state and federal governments each committed $5 billion for the rail link, which will run via a new "super-station" in Sunshine, 11km west of the CBD.
Its estimated cost is $8 billion to $13 billion.
The premier said Victorians had waited too long for the project.
"Getting to and from the airport is very important, there's no more efficient way to do that than a heavy rail link," Mr Andrews said.
In 2016/17, Melbourne Airport handled more than 35 million passenger movements and by 2038, that number's expected to almost double to about 67 million.
"The airport simply won't function without this rail link," the premier said.
Frequency, train speeds, stations and price to the airport will be determined by the business case, due next year.
The exact route would also be established, with the government relying on engineers about whether tunnels were needed, Mr Andrews said.
He couldn't say whether the link would be faster than a taxi or the existing bus service, but said it was important to provide choices.
Former Liberal prime minister Malcolm Turnbull said his government pledged the funds last April and affordable mass transit was vital for a modern city.
"Glad to see the project is going ahead. Long overdue," he tweeted.
The rail link aims to alleviate congestion on the main road to the airport, the Tullamarine Freeway, and cater to the growing population in Melbourne's northwest.
