Almost three hundred homes have got the green light despite fears the development would create a "rat run" through a neighbouring estate.
More than 200 people objected to a bid to build 293 homes near Millmount Road in Dundonald - many of them residents whose houses will now front onto a link to the dual-carriageway.
But Lisburn and Castlereagh councillors said they didn't have the "pure policy" grounds to push back against planners' and road services' approval.
It passed at yesterday’s [Monday March 2] planning committee meeting seven votes to one.
Alliance Castlereagh East Councillor Martin Gregg said the planners' decision was based on "flawed responses" from road chiefs and "outdated" traffic data.
He added: "Roads have let everybody down. 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" and "fully within" department guidelines.
He said the fear that the spine road could turn into a rat run was "a complete misconception".
He added: "There’s no logic to it. It’s [the road] to the benefit of the entirety of Coopers Mill and Millmount [estates]."
Andrew Jackson lives on a cul-de-sac in Coopers Mill which the new road will now cut through.
Residents have waited more than decade for community facilities. The dead-end is the only shared space his son and neighbouring kids have to play.
He said: "The original concept was to have this village centre but they’re still passing applications without that. The voting was very disappointing."
A Department of Infrastructure spokesman said traffic calming could "reduce it's [road] appeal as a rat run".
He said: "It would probably be sensible to have that brought forward for the entire development in order to create a coherent and un-rat run friendly road."
