The Newman LNP government announced the BaT Tunnel in 2013, after Labor's Cross River Rail project was scrapped. The $5 billion project would have been a two-level tunnel, with trains running below the buses.

Upon its election in 2015, the Palaszczuk Labor government in turn scrapped the BaT Tunnel in favour of a resurrected Cross River Rail.

That decision was met with anger at City Hall, with Lord Mayor Graham Quirk threatening to bypass the state government and lobby the federal government to get the BaT Tunnel built.

But following the release of the council's revised Brisbane Metro transit system, which would use bi-articulated buses on high-frequency routes, Cr Schrinner said it was a good thing the BaT Tunnel had been abandoned.

"The intent of the BaT Tunnel was good because it was trying to solve two problems with one project and it's good to have that kind of thinking," he said.

"But still, it was a $5 billion-plus project and it would have also created significant challenges in terms of the bus network and how the bus network flowed through the infrastructure.

"The key challenge with BaT was that the buses would have had to go through the entire tunnel and come out the other end - there was no turning ability so they could have turned around at the city and come back.

"That meant they would have had to go all the way through, up to beyond Roma Street, and that created some dead running in itself."

Cr Schrinner said while that would not have been an insurmountable problem, it would not have been an efficient use of buses.

"So I think, with the revised Cross River Rail and the revised Brisbane Metro, overall we have a much better solution," he said.

It was revealed on Saturday that the Brisbane Metro project would eventually be extended beyond its initial termini of Eight Mile Plains, the University of Queensland and Herston to take in Springwood, Chermside and Carindale along dedicated busways or bus lanes.

It was a move welcomed by Rail: Back on Track public transport lobbyist Robert Dow, who said the extensions could go even further.

And the Labor opposition's public transport spokesman, Jared Cassidy, noted its similarity with 2015 lord mayoral candidate Rod Harding's 2015 transitway election commitment.

"I don't think banana buses are bad, but it's certainly not the Brisbane Metro that was promised at the election," Cr Cassidy said.

"We're not opposed to this plan, although we do want to see details. Getting this humming along is great, but what's next?"

Cr Cassidy said Labor's proposed light rail system that it took to last year's election remained a part of its platform going forward.

"If you deal with this capacity issue on the busway, it still leaves open the possibility of light rail," he said.

"It changes slightly in terms of if the UQ link with the banana buses works out, so the route could look a bit different - there could be a river crossing at a different point for us.

"But we're still committed to a light rail at this stage."

Mr Dow, who had been a vocal critic of the BaT Tunnel and the original Brisbane Metro plans, said he had been turned around with the council's new Brisbane Metro project.

But he said it could go even further.

"An additional metro line should be considered to the Centenary Suburbs via Indooroopilly," Mr Dow said.

"Too many bus routes are coming into the CBD via Coronation Drive and that means higher costs and an overly complex bus network.

"A western suburbs line on the Brisbane Metro could simplify that significantly, increase efficiency and free up even more buses for deployment to increased frequency on feeder and coverage routes."

Cr Schrinner said he was pleased to have won some of the Brisbane Metro's most vocal critics over.

"It just goes to show that when you're doing a genuine business case process and you're doing genuine consultation, then good things often come out of it," he said.

"During the initial phase of developing the metro concept, it was all about clearing some of the key bottlenecks in the network, but when you start thinking outside the square and looking at options through a business case process, then it can be really positive.

"It wasn't just the project team that gave really worthwhile feedback; it was particularly the community and external groups like Rail: Back on Track and other interested parties.

"So it's been a great collaborative process that has made the project better and I think the project will continue to improve."

Cr Cassidy had another theory about the change of heart.

"My general view on a lot of things the deputy mayor is saying and doing is that he's trying to put his stamp on things, particularly around cycling and public transport and things like that," he said.

"My guess is that he's trying to set up his run for the mayoralty as well and that's why we're seeing a softening on certain things and him changing his language here and there."