There is a growing effort underway to complete the Silver Comet Trail, and connect it to Atlanta's Beltline. The section would follow the remnant of the Silver Comet track, still owned, but unused, by CSX, which extends from approximately the intersection of South Cobb Drive and the East West Connector in Cobb County, to a point near Collier Road in the Buckhead section of Atlanta. The old Silver Comet track terminates near an existing Beltline trail.
I've compiled some "for more info" links at
atlantalarry