It’s a new traffic interchange that comes with its own slogan: “Arrive. Crossover. Drive.”
Drivers will be driving on left side of the road on Georgia’s first Diverging Diamond Interchange (DDI) that is being constructed at I-285 and Ashford Dunwoody Road.
The DDI “will eliminate left-hand turns,” said David Purcell, chief operating officer for the Perimeter Community Improvement Districts (PCIDs).
Left turns are “one of the most dangerous traffic operations,” Purcell said.
Construction began in January on the project, which was initiated by PCIDs. The project is a partnership with the Georgia Department of Transportation, DeKalb County and the State Road and Tollway Authority.
The interchange is designed to be a low-cost solution to improve traffic flow and safety. When traffic is moving freely on surrounding highways, particularly I-285, the DDI is projected to reduce traffic delays during evening rush hours up to 20 percent.
The interchange is expected to save a fraction of a second per car at a bridge that handles more than 53,000 cars a day, Purcell said.
However, the interchange is not a “silver bullet,” he said. “If I-285 is not moving, the DDI will not be an improvement.”
Purcell said the interchange will also help the environment by reducing greenhouse gases from idling vehicles.
Pedestrians will be able to walk across the center of the bridge on a median protected by 3-foot high walls.
The interchange is expected to be open for traffic June 4, but it will not be complete. Drivers will have to contend with detour signs and orange road construction barrels until the project is finished later this year.
The DDI will be the 12th such interchange in the country. There are five in Missouri, four in Utah and one each in Kentucky and Tennessee. Several others are under construction around the country and still others are being proposed, including some in Gwinnett County.
Donna Mahaffey, chief of external affairs for PCIDs, said the interchange is a temporary, decade-long solution. The bridge on Ashford Dunwoody Road needs to be replaced with a wider one.
“A new bridge has been on the books for years,” Mahaffey said.
The cost to completely tear down the existing bridge and one a new bridge would be approximately $175 million, Mahaffey said.
Compare that price tag to the $4.6 million contract awarded to E.R. Snell Contractors Inc. of Snellville, by the Georgia Department of Transportation for the DDI project.
“We still do need that complete reconfiguration,” Mahaffey said.
As part of the ongoing public education campaign for the interchange, the Perimeter CIDs is holding a simulation of the interchange May 19, 10 a.m. - 2 p.m. at Perimeter Mall. The demonstration will be in the event lot on the corner of Ashford Dunwoody Road and Perimeter Center West.
Golf carts will be used on a simulated track to allow drivers to experience the new DDI interchange that is being created at I-285 and Ashford Dunwoody Road. A valid driver’s license is required to participate in the test drive.
“It’s not high-tech, but it will make it more real for people,” Mahaffey said.
A simulation of the I-285 and Ashford Dunwoody Interchange DDI is available online at www.perimetercid.org.