Pathway to an Improved Commute

Your resource for the latest Transform 285/400 updates and its transportation impacts in Perimeter.

Under Construction: Transform 285/400

Transform 285/400

Led by the Georgia Department of Transportation, the I-285 at GA 400 interchange is undergoing a major upgrade over a 4-year coordinated construction period that will add roadway capacity, improve traffic flow, safety and access, and generate opportunity for new investment in the Perimeter area. Construction for the project is scheduled for completion in 2021.

Rendering: Transform 285/400

Occasional Detours: Mount Vernon Highway


GDOT crews have completed the first phase of the Mount Vernon Highway bridge reconstruction, reaching a new milestone in the Transform 285 @ 400 transportation project.

The final phase of work on Mount Vernon Highway begins in February 2020 and will last through the end of 2021.

During that time, GDOT will conduct a traffic switch on Mount Vernon Highway over SR 400. All vehicle and pedestrian traffic will move to the new section of the bridge, and the old bridge will close for demolition for the final phase of construction.

Occasional evening (9 PM to 5 AM) or weekend detours or other changes on Mount Vernon may be needed.

A complete list of lane closures or impacts for the coming week is posted by GDOT each Friday. Click the button below to view the list.

Major Lane Closure: Peachtree Dunwoody Road

There are construction-related realignments on Peachtree Dunwoody Road implemented on April 29, 2019, that will continue through the end of the 285/400 reconstruction (expected to be completed by end-of-year 2021).

During this construction period, there will be one northbound lane, rather than two, on Peachtree Dunwoody as it passes under I-285. While the alignment of lanes on southbound Peachtree Dunwoody will shift, the number of lanes will remain the same.

Here’s a look at the long-term and final lane changes to Peachtree Dunwoody Road.

Upcoming Major Road Realignment

There are construction-related lane realignments coming soon to Abernathy Road that will continue through until the completion of Transform 285/400. Once made, the lane modifications will allow Georgia DOT crews to begin construction on a Diverging Diamond Interchange (DDI) to shift drivers to the opposite side of the road to improve traffic flow and safety. The DDI is expected to be completed by 2021.

Project Status

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Transform 285/400 By The Numbers

10.5 MILES

includes 4.3 miles of upgrades on I-285, from Roswell Road to Ashford Dunwoody Road, and 6.2 miles on GA 400, from Glenridge Connector to Spalding Drive.


The project kicked off in February 2017 and is expected to be completed in 2021.


in construction upgrades to improve travel conditions and access on the interchange.

20,000 HOURS

Improvements are estimated to save GA 400 and I-285 travelers this total amount each day

Perimeter Community Improvement Districts