Northbourne Avenue could have dedicated bus and cycle lanes carved out of its median strip, under options being considered by the Canberra Liberals in their push against the Government's light rail project.

The party has pledged to cancel the $800 million Gungahlin-to-Civic line, arguing the cost provides little benefit.

Opposition spokesman Alistair Coe said a newly-released options paper set out an alternative vision.

"We're very keen to have a genuine discussion with the community about what the public transport options are for Northbourne Avenue," he said.

The paper puts forward three options, with buses either travelling in a dedicated lane in the centre median or through priority lanes at major intersections between Antill Street and Barry Drive.

"At present, whether you're on a bus or in a car that can take as much as 15 or 20 minutes," Mr Coe said.

"With a bus lane going down the median of Northbourne Avenue that journey time could be as short as five or six minutes."

That lane would travel in only one direction, with express buses heading southbound in the morning peak and northbound in the afternoon.

The Opposition has costed the cheapest option at $20 million, with the most expensive at more than $100 million.

"Whilst it is fairly expensive, it is still a fraction of the cost of light rail and it also doesn't have the operating expenses," Mr Coe said.

The Liberals have called on both the Government and wider community to give feedback on the paper.

"The Government did a deal with the Greens in order to get light rail off the ground, but that's not going to be the genesis of our transport planning," Mr Coe said.

"Our transport planning is going to be based on genuine options, genuine cost-benefit analysis and genuine consultation with the community."

Cost of tearing up light rail contracts not included, minister says

But Minister for Roads Mick Gentleman said light rail addressed the critical issue of congestion, which is predicted to worsen as Canberra's population expands.

"We need to reflect on the Infrastructure Australia report showing that the cost of do-nothing or similar approaches that we're doing now will cost us over $700 million per year in congestion by 2031," he said.

"This is why we're taking this active role in moving to light rail transport."

Mr Gentleman also questioned the costings in the report.

"We're concerned that that does not cover the cost of ripping up the contract for light rail," he said.

He said the ACT Government's strategy for urban renewal would be out shortly for public comment.

"We know by 2050 the population of the city and north Canberra is anticipated by more than 80 per cent. We need to respond to these emerging challenges," he said.

The ACT Government is set to begin construction of light rail next year, and Capital Metro Minister Simon Corbell has maintained the project will be a huge improvement for transport in Canberra.