The additional work means an extra six months of construction in an area that has seen plenty of orange barrels since construction began in November 2017.
The junction of I-285 and Ga. 400 is one of the region’s worst traffic bottlenecks. About 420,000 vehicles a day pass through the interchange, which was designed to accommodate about 100,000.
The project includes new “flyover” ramps and lanes adjacent to both highways. It also includes a diverging-diamond interchange at Ga. 400 and Abernathy Road and a new bridge at Mount Vernon Highway.
When it’s completed, the interchange will be almost as big as Spaghetti Junction — where I-285 meets I-85 northeast of Atlanta — and should save the average commuter about eight hours a year spent in traffic.
Ann Hanlon, the executive director of the Perimeter Community Improvement Districts, said the interchange will be a boon to an area that’s home to Fortune 500 companies, several hospitals and Georgia’s second-largest shopping mall.
“I really cannot overstate how important the project is for our district,” she said.
Hanlon said the extra six months of construction won’t cause a major headache. And it will allow the district and GDOT to build a connection to Path 400 — the bike and pedestrian path — under I-285 at Peachtree-Dunwoody.
“This project is going to need to last us for a long time,” Hanlon said. “It’s important that we get it done right.”
The new interchange will serve as the linchpin of metro Atlanta's growing network of toll lanes. In addition to those that have already opened, the state plans lanes along the top half of the Perimeter and along Ga. 400 in Fulton and Forsyth counties. Eventually, there will be 120 miles of toll lanes across the region.