The Transform 285/400 project will be substantially complete by third-quarter 2022, giving motorists full use of the roadway, according to the Georgia Department of Transportation (GDOT).
Many of the retaining walls, noise barriers, bridges, drainage structures, and new ramp alignments have been completed, GDOT spokesperson Natalie Dale said.
Previous project timelines had anticipated substantial completion by December 2021.
But, the construction industry is experiencing labor, materials and equipment shortages, which aren’t unique to GDOT and this project, Dale said.
“It’s also important to remember that this project to rebuild one of the nation’s busiest interchanges is one of the largest and most complex of its kind in the country, with construction continuing at a steady pace while the interchange continues to serve up to 400,000 vehicles each day,” Dale said.
Roadway alignments that have been completed include the southbound Abernathy Road off ramp, the ramps from Ga. 400 southbound to I-285 eastbound and westbound, and ramps from westbound I-285 to Roswell Road and eastbound I-285 to Glenridge Drive. Dale said those parts of the project aren’t in their final configuration, but they have been relocated to allow continuation of the work.
For the Abernathy and Hammond interchanges, all the ramp alignments are changing, she said. Current access to Ga. 400 northbound and southbound will continue with fewer merges and weaving conflicts.
Southbound motorists on Ga. 400 looking to exit at Abernathy Road, Hammond Drive, I-285 or the Glenridge Connector, will leave the through lanes much farther north, merging into the collector distributor lane near Spalding Drive.
Abernathy Road Interchange
The Abernathy Road interchange will be a diverging diamond interchange, or DDI, she said. It will look and function much like the existing Ashford Dunwoody Road interchange. The Abernathy DDI will be under Ga. 400, while the Ashford Dunwoody DDI is over I-285.
The new ramps are under construction and the new collector-distributor bridges on each side of Abernathy are nearing completion. GDOT will demolish the existing Ga. 400 bridge over Abernathy and replace it.
Motorists leaving Abernathy for northbound Ga. 400 will see the ramp merge with the MARTA North Springs ramp, then entering Ga. 400 north of Spalding Drive.
Hammond Drive Interchange
The Hammond Drive on and off ramps will connect to the new northbound and southbound collector-distributor lanes on Ga. 400, Dale said. The entrance to the southbound off ramp will move north of the MARTA flyover. Entry to Ga. 400 northbound from Hammond Drive will move north near Pitts Road, she said.
“Northbound access to Abernathy Road from Hammond Drive will remain; however, southbound access to Hammond Drive from Abernathy Road will be removed,” Dale said.
Southbound on Ga. 400 to I-285
Motorists who want to access I-285 eastbound or westbound will need to enter the collector-distributor lane which begins north of the North Springs MARTA station flyover. Alternate access to that southbound collector-distributor lane will be just north of Abernathy Road, she said.
The southbound Ga. 400 to I-285 westbound ramp will allow drivers to exit to Roswell Road without having to enter I-285. In its final configuration, the temporary connection to I-285 now located before Roswell Road moves west past Roswell Road. This will allow the Roswell Road westbound on ramp to join it before merging back onto I-285.
The I-285 ramps will be two lanes when complete.
Northbound on Ga. 400 to I-285
The Ga. 400 northbound to I-285 westbound loop ramp is close to its final location. The new northbound to I-285 eastbound ramp will merge with the Ga. 400 southbound to I-285 eastbound ramp into a new collector-distributor lane. It then enters I-285 east of Ashford Dunwoody Road. From this lane drivers will be able to exit to Ashford Dunwoody Road, Dale said.
This collector-distributor lane will continue to Hammond Drive. At that point it will enable access to Ga. 400 northbound.
I-285 westbound to Ga. 400 northbound/southbound
The new westbound exit to Peachtree Dunwoody will move to the north, she said. The other lanes in this area are exits to Ga. 400 north and south, with a connection to Roswell Road. These are temporary.
When the collector-distributor lane in the westbound direction of I-285 is complete, motorists will enter between Chamblee Dunwoody and Ashford Dunwoody. This allows drivers to exit to Ashford Dunwoody, Peachtree Dunwoody, Ga. 400 northbound and southbound, and Roswell Road. It also enables drivers to return to I-285 westbound.
I-285 eastbound to Ga. 400
When the collector-distributor lane on eastbound I-285 is complete, motorists will enter just before Roswell Road. This allows access to Glenridge Drive and Ga. 400 northbound and southbound.