Some community councils fear the Kings and Commonwealth Avenue redevelopment plans have been based around incorrect traffic figures and could bring traffic to a halt across Canberra south.
The National Capital Authority in May unveiled plans to reconfigure the roads as grand boulevards for easy cycling and walking.
The plans would see clover leaf on and off ramps on Kings and Commonwealth Avenues dismantled, speed limits reduced to 60km/h and opening up land either side of the avenue for development.
In submissions made during the community consultation period, the Inner South Canberra Community Council and Griffith/Narrabundah Community Associations said the plans ignored the critical transport roles of both avenues.
South Canberra council chair Marea Fatseas said she feared traffic would come to a standstill across parts of Canberra and the authority had based the draft design on completely inaccurate traffic figures.
The draft design strategy acknowledged the increasing traffic along Commonwealth Avenue stating "each day more than 20,000 cars, buses and trucks travel along Commonwealth Avenue alone".
But ACT Roads figures show actual daily traffic flows on Commonwealth Avenue was about 67,000 vehicles a day, making it Canberra's busiest road.
"I'm envisaging traffic all the way from Civic to Woden," she said.
"We've got them saying we're going to make a lovely grand boulevard ... which is all very well in theory but then you've got this massive bottle neck coming along."
Ms Fatseas said she was concerned the authority had developed a design for the area without working outthe impact for people who currently use that corridor.
"When I rang the NCA and asked for traffic modelling report, they said it was a concept plan and one hadn't been done," Ms Fatseas said.
"The problem is it's already effectively been legislated on a federal level and included in the National Capital plan.
"In other words, we have both a legislated, very specific precinct code for West Basin in the National Capital Plan, and also a full blown City to the Lake development being implemented by the ACT government, without evidence of traffic modelling and integrated transport/land use planning.
"It's a very strange way to make public policy with multi-million dollar expenditure implications."
Ms Fatseas said she wanted to know the federal and ACT governments were talking to each other, as well as engaging urban and transport planners and the broader community.
The Griffith/Narrabundah Community Association's submission labelled the draft design "deeply disturbing".
It questioned whether the driver for the changes advocated was to free up land for development that is currently unusable because of cloverleaf off and on ramps.
The authority was contacted for comment but did not respond by deadline.