Progress on a long-delayed rail project to Australia's second-largest airport is welcome but unlikely to shave time off the bus trip, a transport expert says.
Victorian Premier Ben Carroll stood beside Prime Minister Anthony Albanese on Wednesday to commit work on stage two of the Melbourne Airport rail link.
The 7.4km stretch of rail will connect Albion, in the city's outer west, to the airport via a new Keilor East station, with construction to begin in 2028.
It's the second of three stages in a project that is designed to eventually connect the Melbourne's city centre to its largest airport.
But when the project will be fully delivered, and whether it will make for a shorter journey than by bus, is a matter of ongoing debate.
Graham Currie, a public transport expert at Monash University, said the SkyBus, which offers an average 30-minute trip to Southern Cross Station in the city's centre, will likely remain the faster option.
A 2022 business case for the rail project states its 30-minute journey will make for a shorter trip than the SkyBus during peak periods.
But Professor Currie stressed that, unlike the bus, the rail link would involve a dog-legged journey through Melbourne's outer west, adding time to the journey.
"It's likely to be less competitive because we decided not to go for the expensive direct route," Prof Currie told AAP.
Mr Carroll on Wednesday said he was "getting on and delivering" a direct rail link to the airport that would electrify the northwest.
"This is really important for Melbourne," he said.
Earlier, he described the project as "transformative".
Major construction is not slated to start on stage two until 2028, though site investigations and procurement will begin within weeks.
The $12 billion joint commitment from the state and federal Labor governments is expected to be completed in 2031, one year after stage one of the project.
The $4.1 billion first phase will untangle 6km of track between West Footscray and Albion into a six-platform Sunshine super hub.
But there is still no word on when the final stage of the project will be complete.
Establishing an airport rail in Melbourne has been toyed with since the 1960s, but has been plagued by decades of backflips and delays.
Prof Currie said the lack of a direct rail link to its largest airport had left a "big gap" in Melbourne's city design.
"Sydney's got one, Brisbane's got one, Perth's got one, all the big places have got one, and Melbourne doesn't," Prof Currie said.
The state coalition on Wednesday also backed the project.
"This will be a priority of ours if we are elected in November," Opposition Leader Jess Wilson said.
"There'll be no more delays."
