The federal government has committed $50 million to Stage 2B of Canberra's light rail ahead of next week's federal budget.
The money will go towards designing the 10-kilometre extension from Commonwealth Park to Woden.
The ACT government is yet to reveal the estimated cost of building Stage 2B, arguing the price tag can't be confirmed amid contract negotiations, planning and approvals.
But there is an indicative timeline, with construction estimated between 2028 and 2033.
ACT Transport Minister Chris Steel said the funding was what the territory asked for, and showed the federal government was now backing the next stage of the project.
"This is a very important moment for transport in our city's history," he said.
"It is the first time that an Australian government is backing the next stage of light rail."
He said both governments were committed to building an integrated public transport network to cater for Canberra's growing population, which is expected to reach more than 780,000 by 2060.
Stage 2B community consultation
Public consultation is now open on the environmental impact of Stage 2B and will include pop-up information stands in shopping centres and information sessions with the project team.
"We're seeking feedback, particularly through the Parliamentary Triangle, on an alternative route through Barton and the three alternative stops there," Mr Steel said.
He said the route along Adelaide Avenue on the median strip, through Yarra Glen and into Woden, was "fairly settled".
"But we're seeking feedback from the community about how that corridor should be designed as we go through this process," he said.
"We're asking people living along the line near the stops to provide their feedback about what they'd like to see in terms of the infrastructure that's built ... other public transport connections to the line, landscape, or heritage matters."
Cost, route won't be known before ACT election
Mr Steel said neither the exact route nor the estimated cost would be known before the election, with the draft environmental impact statement (EIS) not expected until the end of the year.
He said Stage 2B required additional approvals that didn't apply to Stage 1, and that meant the cost of the project couldn't be calculated until its design and scope were ticked off by all parties – including federal parliament and the National Capital Authority.
The federal government has already committed $343.9 million for the 1.7-kilometre Stage 2A that is currently under construction – half the estimated price tag.
Finance Minister and ACT Senator Katy Gallagher said the project was a "great investment in the future of Canberra" and served as a "physical demonstration" of the ACT and Commonwealth's current partnership.
"Light rail has been a transformative project for the ACT," she said.
"We know Canberrans love light rail, they've really embraced it, anyone who sees it on the northside of Canberra can see why it would be attractive to get it to the southside of Canberra."
'Liberals the most negative I've ever seen'
During this morning's announcement Federal Infrastructure Minister Catherine King slammed the Canberra Liberals' public transport policy.
Ms King wouldn't be drawn on whether the Commonwealth funding would be redirected to other projects if the Canberra Liberals won October's election and Stage 2B didn't go ahead.
"It's pretty clear that only Labor cares about public transport, cares about making sure we actually have those transport routes," he said.
"We're getting on with the job of building Canberra.
"The Liberals, frankly, are just the most negative I've ever seen."
ACT Opposition Leader Elizabeth Lee said she was disappointed with Ms King's criticism of her party's approach to light rail.
"It's incredibly disappointing that Ms King, without having had a single conversation with me, decided to play politics and criticise what we're doing," Ms Lee said.
"The fact is we have released a comprehensive public transport policy, it's absolutely clear that Ms King has not even bothered to look at what we have planned for public transport in the ACT."
Ms Lee called the federal government's announcement "a stunt" conducted on the eve of the federal budget.
"We have no detail about what that [$50 million] is going to be for, let's not forget we still have no understanding about the true cost of the entire project, what route its going to be on," she said.
Ryan Hemsley from the Public Transport Association of Canberra welcomed the funding and said they supported the extension of light rail.
But he said neither major party in the ACT was offering a complete policy solution for Canberra's growing transport needs.
Both parties plan to acquire more electric buses in coming years, but Mr Hemsley said Labor should match the Canberra Liberals' and ACT Greens' commitments to increase bus frequency to seven days a week.
"What we have at the moment is an opposition with a bus policy that has no mass transit element and a government that has a mass transit policy with no bus element," he said.