Connecting Communities: I-285/SR-400 Interchange Reconstruction by Willmer Engineering

The project objective is to improve travel times and safety in the vicinity of the I-285/SR 400 interchange. It is a priority for the metro Atlanta region and will be advanced through innovative project delivery efforts.

The project is constructed using Design Build Finance (DBF) and Public Private Partnership (P3). It is located on the Top End of I-285, beginning west of Roswell Road in Fulton County and ending east of Ashford Dunwoody Road in DeKalb County, a length of approximately 4.3 miles. It also includes approximately 1.2 miles of improvements on SR 400 from the Glenridge Connector to Hammond Drive.

The project includes constructing new eastbound and westbound CD lanes along I-285, as well as northbound and southbound CD lanes along SR-400, new flyover bridges, reconstruction of existing ramps, and widening of existing bridges within the interchange. “Braided” ramps are to be constructed in the vicinities of Ashford Dunwoody Road and Roswell Road to eliminate conflicts between traffic entering and exiting SR 400 and traffic entering and exiting the Roswell Road and Ashford Dunwoody interchanges, while preserving the recently completed projects at both of these interchanges. Along SR 400, the project would construct northbound and southbound CD lanes from Glenridge Connector to Hammond Drive. This work will tie into the adjacent SR 400 CD lanes project.

Willmer provided geotechnical analyses for roadways, bridges, and wall concepts for the design/build team bid. During final design, Willmer provides review of all geotechnical reports produced for GDOT. During construction, Willmer provides GDOT CEI services as the oversite material manager for material sampling and testing, including monitoring and auditing the builder’s quality control sampling and testing. Willmer also provides all responses to contractor foundation and earthwork RFIs.


Fulton/DeKalb Counties, Georgia


Transportation Infrastructure


Geotechnical Engineering
CEI Services



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