The NRMA has responded with caution to a proposal to abolish existing taxes on motorists in favour of congestion, distance and access charges.
The draft proposal was released by Infrastructure Partnerships Australia chief executive Brendan Lyon, who said existing models for roads were broken and could not fund required improvements.
"At its most fundamental, transport is broken because we don't have the money needed for new and renewed infrastructure and we use the networks we have very poorly," he said. "This problem can and will be fixed by pricing reforms that spread capital city peaks, better recover freight costs and make the system fairer and better for motorists," he said.
The group, which represents major Australian consultancy firms and state infrastructure departments, said existing public transport and road networks were failing to cater for a growing population and congestion costs.
Department of Infrastructure and Regional Development modelling released last year found the cost of congestion on Canberra roads is set to double to $400 million by 2030 unless major projects are completed.
The model proposed by Mr Lyon could see motorists charged 3.77¢ per kilometre with a congestion charge of 7¢ during the morning peak and 6¢ during the afternoon peak. Motorists would also be charged a weekly road access fee of $1.10 a week.
The ACT government has rejected the proposal with a spokesman stating it should first be trialled in a larger city with an established network of priced roads and heavier congestion.
"We understand that Sydney has undertaken early tests of basic road pricing through its time of day tolling for the Sydney Harbour tunnel and bridge," he said.
An NRMA spokesman said the group welcomed new policy initiatives but warned it would not support any scheme that charged motorists more than they currently are.
"We are open to the debate and there is a lot of talk about alternative pricing methods at the moment but they need to be a substitute for existing models, not an addition," a spokesman said.
"The reality is that we already have an indexed petrol tax that will increase in coming years and motorists are already paying their fair share. We don't want to see them paying more.
"We need to improve public transport infrastructure and if you are going to tax people more for using their car then you need to give them better alternatives modes of transport."
Mr Lyon said the proposal was likely to concern many motorists but insisted it would be subject to detailed trials and planning.
"The transport network is costing us time and money because we cannot afford the new road and rail infrastructure we need and we use what we already have badly."
With an election looming, the Liberal and Labor parties have pledged to upgrade arterial roads including the duplication of the Cotter Road at an estimated $25 million, despite opposition from the ACT Greens.
The Liberals have also pledged $146 million for the duplication of Gundaroo Drive and a new flyover on the Barton Highway near Gungahlin.
The government has already spent more than $3 million on upgrades to the city to Gungahlin corridor for the construction of the light rail line, which is outside the $783 million price tag for the tram line.