Ballarat commuters will eventually have a faster trip to Melbourne's Tullamarine airport, with the state and federal government committing $10 billion to fund a rail link through Sunshine.
Scott Morrison and Daniel Andrews will sign a Heads of Agreement setting out the key terms in Melbourne on Wednesday, with a view to the nine-year construction project getting underway in 2022.
The state and federal governments have each committed $5 billion for the rail link, which will run via a new "super-station" in Sunshine, 11km west of the CBD.
The Ballarat Public Transport Users Association's Ben Lever said the Sunshine route may also bring other benefits.
"This option provides a direct service, while still providing great connectivity to the Ballarat line, and other regional and metro lines," he said.
"The state government's Western Rail Plan is currently investigating options for improving the existing lines in the western suburbs and western Victoria, and today's agreement provides for a business case that will work out both how the airport link will work, and how it will interact with those other lines."
The total cost is estimated at $8 billion to $13 billion.
Mr Morrison said Victorians have been waiting decades for an airport rail link to become reality.
"The rail link is part of our plan to bust congestion across the city, and get people home faster and safer," he said.
The project will connect Melbourne Airport at Tullamarine to the city's rail network. It will also integrate with the Metro Tunnel and a future suburban rail loop, paving the way for fast rail to the regions.
Premier Andrews said opting for the Sunshine rail route ensures all Victorians benefit from the link, including residents of Geelong, Ballarat and Bendigo.
"As we complete the business case, we're also doing the work needed to deliver fast rail to the regions," he said.
The rail link aims to alleviate congestion on the main road to the airport, the Tullamarine Freeway, and cater to a growing population in Melbourne's north- west.
In 2016/17, Melbourne Airport handled more than 35 million passenger movements and by 2038, that number's expected to almost double to around 67 million.
Federal Minister for Cities, Urban Infrastructure and Population Alan Tudge said following the successful widening of the Tullamarine Freeway, the airport link was the next critical link.
"This is a critical project for Melbourne. It will make it easier for residents and make our city more attractive to visitors," Mr Tudge said.
"When complete, someone in Pakenham, Frankston or Ringwood will be able to get onto the train and be at the airport in the time it would have taken to drive, but without having to worry about parking."