High-speed rail linking Melbourne to Brisbane via Canberra and Sydney would cost Aus$114 billion (US$120 billion) and take more than 40 years to complete, a government study showed Thursday.
Australia has debated the merits of high-speed rail connecting the main centres along its east coast since the 1980s but has never committed to such a major project.
Transport Minister Anthony Albanese, who commissioned the feasibility study in 2010, said it would transform the way people along the eastern corridor -- home to about two thirds of Australia's population -- live and work.
But he conceded there were technical, logistical and financial challenges as he released details of the study.
Asked if the government was serious about pressing on with high-speed rail despite the hefty price tag, he said: "Yes, we are.
"But there's no doubt that for a project which is 1,700 kilometres (1,050 miles) long, that would involve some 144 kilometres of tunnelling, that it would take time for construction to commence."
The study shows the total capital cost would be AUS$114 billion, including project development and construction funding, with limited potential to attract private investment due to poor rates of return.
"It's pretty clear that this would require a substantial commitment by the national government," Albanese said.
"It's also the case that you could get some state and territory government contributions."
But he insisted it could deliver a positive economic benefit, with the study showing the line would be capable of carrying 84 million passengers a year.
"(The study) estimates that overall there is a significant economic benefit, a return of $2.30 to Australia's economy for every dollar that is invested," he said.
A journey from Sydney to Melbourne that currently takes some 12 hours by rail would take just two hours and 44 minutes on trains travelling at an average of 300 kph (186 mph).
Travel from Sydney to the capital Canberra would be reduced from four hours to 64 minutes while commuters from Sydney to Brisbane could make the trip in two hours 37 minutes instead of the current 13 hours.
The study said the 1,784-kilometre route from Melbourne to Brisbane would not be complete until 2058, with the first trains unlikely to run on the first stretch of track until at least 2030.
The proposal will now be put to public consultation, but whether it ever goes ahead remains to be seen, with the conservative opposition widely tipped to win national elections in September casting doubt on its feasibility.
"It's certainly a great dream that people have been thinking about for a very long time, but the cost of $114 billion estimated at this stage is obviously a huge barrier," said opposition transport spokesman Warren Truss.