Georgia Department
of Transportation

North Perimeter

Bridge design


Roadway and

Construction Cost
$ 600 M estimated
total project

2022 estimated

Delivery Method

Project Sheet
pdf (attached project sheet)


I 285 and SH 400 Interchange Reconstruction

Atlanta, GA

DECON designed nine of the 32 bridges built as part of the I 285 at SH 400 Interchange Reconstruction project, which provided barrier-rail-separated CD lanes. The program included reconstruction of the existing ramps, new flyover directional ramp bridges, reconstruction and widening of existing bridges in the interchange area, braided ramps at the Ashford Dunwoody Road and Roswell Road interchange and two miles of improvements along SH-400 from Glenridge Connector north to Hammond Drive.

The SH 400 CD lanes along SH 400, from its southern limit at Hammond Drive north to Spalding Drive, required reconstruction of the existing Mt. Vernon Road bridge over Abernathy Road, and improvements to the SH 400 interchange at Abernathy. Bridge design in this project was based on LRFD Specifications 7th Edition w/ 2015 interim revisions.

When brought onto the program, DECON analyzed the existing schematic and redesigned it, which saved $1 M in construction cost. The complex project required continual, effective communication with multiple other consultants and the developer to produce construction documents and quickly obtain Release for Construction permits from the Georgia Department of Transportation (GDOT). Using their experience on major bridge programs in Texas with advanced technologies and processes, DECON achieved important schedule and quality goals on this project. These technologies were new to GDOT and had never been used on a GDOT project before.