A development of almost 300 homes has been given planning approval despite concerns the project would create a "rat run" in a neighbouring estate.
More than 200 people objected to the proposal to build 293 homes near Millmount Road in Dundonald, many of them residents whose houses will now front onto a link to a dual-carriageway.
Lisburn and Castlereagh councillors said they did not have the "pure policy" grounds to push back against planners' and road services' approval.
The proposal was passed by the council's planning committee meeting, seven votes to one.
Alliance Castlereagh East councillor Martin Gregg claimed the planners' decision was based upon "flawed responses" from road chiefs and "outdated" traffic data.
He added: "There was no consideration that the traffic has completely changed.
"You're going to be putting thousands of cars and commercial vehicles on an open-plan residential street."
But a representative for the developer said the traffic assessment, from 2015, was "put through a rigorous process".
He said the fear that the road could turn into a rat run was "a complete misconception".
He added: "There's no logic to it. (The road) is to the benefit of the entirety of the Coopers Mill and Millmount (estates)."
The Department for Infrastructure said traffic calming measures could "reduce (the road's) appeal as a rat run".
A spokesman added: "It would probably be sensible to have that brought forward in order to create a coherent and un-rat run friendly road."