The Georgia Department of Transportation has released an illustrated video showing the Ga. 400 toll lane design, which includes three rebuilt bridges and a high flyover atop the Northridge Road overpass in Sandy Springs.

The video was released at a Feb. 28 meeting kicking off the public input process. GDOT is working on two projects that would add four new toll lanes, called “express lanes” or “managed lanes,” along I-285 and Ga. 400 in the Perimeter Center area over the next decade, with the intent of improving overall traffic flow. The toll lanes are part of a system being built metro-wide, including recently opened lanes on I-75 and I-575.

Parts of the toll lanes are expected to be elevated to use existing right of way, although other parts be at-grade and would require building demolitions in Sandy Springs.

YouTube video

The video shows the toll lane design, which is not final and could change, starting at the North Springs MARTA Station where the project begins. GDOT recently shifted the section of Ga. 400 south of the North Springs station into the I-285 toll lanes project, which is undergoing a separate planning process on a later timeline.

The toll lanes start on the outside of Ga. 400 and the collector distributor lanes that are being added as part of the Transform 285/400 project. The toll lanes are elevated on the west side as they pass under the Spalding Drive bridge, which is slated to be replaced as part of the project, before declining back to at-grade.

The lanes pass under the Pitts Road bridge, that is also planned to be replaced, bringing with it realigning of the surface road that would require the demolition of some properties.

Both sides become elevated as the toll lanes pass over the Northridge Road bridge, which is planned to stay. The toll lanes would be about 25 feet above the bridge, GDOT spokesperson Natalie Dale said in an email. The distance between the top of the road to the bottom of the bridge would be 17 feet, she said.

The interchange was dedicated in 2016 as the “Mayor Eva Cohn Galambos Memorial Interchange” for the city’s founding mayor.

After Northridge Road, the toll lanes move to between the Ga. 400 general purpose lanes.

The lanes stay in the center as the pass under the Roberts Drive bridge, which would be replaced, and cross the Chattahoochee River into Roswell. The bridge over the river is planned to be widened to provide room for two toll lanes in each direction.

This article has been updated with additional information about the Northridge Road bridge.