A high-speed train running down the east coast of Australia and then across to Melbourne would cost $114 billion to build but would eventually pay its way, carrying 84 million passengers a year.

After decades of debate, a landmark study commissioned by the federal government as part of a 2010 deal with the Greens has concluded the controversial project would be viable despite the massive cost, with a proposed route from Brisbane to Sydney and then inland to Melbourne, with connections to Canberra and the Gold Coast.

Reaching speeds of up to 350km/h, the rail link would allow passengers to travel from the centre of Melbourne to the heart of Sydney in under three hours.

But it would be expensive, with the section between Sydney, Canberra and Melbourne costing $50 billion and Brisbane to Sydney $64 billion in today's dollars.