A proposed $100 million interchange designed to ease traffic on Adelaide Avenue has been scrapped following the Brickworks redevelopment.

A proposed $100 million interchange designed to ease traffic on Adelaide Avenue has been scrapped following the Brickworks redevelopment.

The ACT government has removed a proposed upgraded interchange on Adelaide Avenue which aimed to smooth traffic flow from Molonglo, Weston Creek and Belconnen following the Canberra Brickworks redevelopment at Yarralumla .

Yarralumla residents say the redevelopment will mean more housing in their suburb, less road upgrades and contamination measures which fall 20 to 30 times short of what is needed.

Freedom-of-Information documents released on Tuesday indicate the ''Mint Interchange''  on the existing Adelaide Avenue and Yarra Glen interchange, with connections to Denison Street and Cotter Road,  would have cost between $80 million and $100 million.

The interchange was a key traffic measure in the 2010 redevelopment masterplan for 1100 new homes at the brickworks, but is not on the revised plans announced in May for 1600 dwellings.

Land Development Agency spokesman Dan Stewart said the current strategy did not include the upgraded interchange because it was not considered necessary for this stage of the development. 

"However, this does not preclude its delivery as part of the next stage of works,'' Mr Stewart said.

FOI documents reveal consultants AECOM prepared a feasibility study on the Mint interchange with four options ranging from $83 million to $104 million for either an elevated roundabout or diamond interchanges.

Traffic modelling indicated the roundabout offered the most efficient solution for general traffic, to reduce delays and queuing at the intersections, but not for pedestrian movement and cycling.

Consultants SMEC reviewed costings in AECOM’s feasibility report, saying:

“Given the location of the proposed interchange is on one of Canberra’s busiest transport corridors, and potentially significant project costs, it is recommended more detail of all potential options be considered and investigated before any are removed from further consideration.’’

Yarralumla Residents Association president Marea Fatseas, who lodged the FOI request, said traffic from Weston Creek, Belconnen and Molonglo suburbs using Cotter Road comes off Dudley Street before turning into either Yarralumla or west Deakin.

But under the latest plan Dudley Street would be replaced with new apartments.

"They will have to re-route traffic either through new streets in the new suburban areas, or if people find that takes too long, potentially they may go through Curtin. If they see queues, they will continue on Adelaide Avenue and  Hopetoun Circuit and into west Deakin through the back way," she said.

Reports in 2001 identified environmental concerns including underground fuel storage, explosive storage, landfill areas, brickworks and kilns and possible contaminants.

Ms Fatseas said asbestos remediation plans had not eased concerns for nearby residents. On the association's calculations, the Land Development Agency, which allowed $5 million for the work, had under-estimated the clean-up task.

"Moreover, the cost estimate does not provide for remediation of the brickworks site as a whole. The association knows, for example, that bricks have been dumped in many areas throughout the brickworks and so the land may be unstable and the bricks themselves may contain contamination,'' Ms Fatseas said.