Infrastructure Australia has again pointed to Belconnen-Civic-Queanbeyan as one of Canberra's worst transport corridors, including bus transit ways connecting the centres on its $55 billion infrastructure priority list.

The bus routes were placed on the list in 2016, but in its latest assessment, the agency said the combination of "limited" public transport network capacity and a high reliance on private vehicles was causing the transport network to suffer from increasing congestion.

"Congestion is likely to be exacerbated by projected significant population growth," the report said.

Infrastructure Australia's executive director of project advisory Anna Chau said she was not "advocating any specific modes" of transport but that the corridors had "options for further improvement".

"We want to get more out of that bus network because what we're seeing is limited public transport capacity," Ms Chau said.

Belconnen Community Council chairman Glen Hyde said Belconnen's buses were already at "crisis point", and the region should get stage three of light rail.

"The number of buses that do not pick up between the community bus stations of a morning because they are full is significant. It doesn't matter if they're articulated buses or one of the larger buses," Mr Hyde said

"Everyone talks about buses failing to turn up as a critical reliability factor but it's not - it's the buses that have to drive by because they're chock-a-block full that really turn people off."

A Queanbeyan-Palerang Regional Council spokesman said they were working with the ACT government to synchronise bus lanes and make existing cross-border services more efficient.

However a NSW government planning paper last week also raised the prospect of extending Canberra's light rail network through to Queanbeyan in the next decade.

Queanbeyan-Palerang mayor Tim Overall said at the time given the future growth of the city, "improved public transport links including light rail is justified financially".

Planning Institute of Australia ACT president Karen Wright said as a regional centre, Canberra needed to "broadly consider" its approach to cross-border transport, with more "streamlined" bus and rail services.

"Currently we have a rail line connecting Canberra to Queanbeyan, but serviced by a slow running, infrequent service at a train station that is not easily accessible," she said.

"Bus transit connections that service and connect Canberra to adjoining areas, is critical for reducing road traffic and providing alternative transport options."

ACT Opposition Leader Alistair Coe said the decision to send light rail to Woden was based on "politics", not "evidence and modelling".

"The current government hasn't done any staging analysis for their light rail investments but has instead chosen routes based on political decisions," Mr Coe said.

However an ACT government spokeswoman said the report had "once again affirmed" the "national significance" of the territory's investments in public transport infrastructure.

Infrastructure Australia also pointed to Gungahlin-Civic as the other problem corridor, urging the territory government to continue building better road, rail and bus transport along it to keep up with the projected population growth.

The ACT government is already duplicating Gundaroo Drive, with $30 million budgeted last year for the second stage of that project.

The duplication of Horse Park Drive is expected to be finished by mid-next year while light rail between Gungahlin and Civic is due for completion this year.

Ms Chau said Infrastructure Australia would re-evaluate Gungahlin-Civic when light rail stage one was completed, to see if more action needed was to alleviate congestion along the corridor.

However the Civic to Woden corridor, where light rail stage two will run, was not identified as one of the problem areas in the report.

Ms Chau said they were happy to look at the need for second stage of light rail if and when the ACT government provided them with a business case for it.

Gungahlin-Civic light rail was only included on the priority list in 2016, three years after they said there was limited evidence of congestion along the corridor.