(a) Except as otherwise provided for in subsection (b) of this Code section, it shall be unlawful for any official, officer, or employee of the department, the State Road and Tollway Authority, the Georgia Highway Authority, or any similar authority or of any county or municipality to authorize the construction or maintenance of any private road.

(b) When acting pursuant to agreement with the United States Department of Defense or other federal entity, the department shall be authorized to construct or maintain a private road upon a military base or military installation, provided that funds expended for such purpose shall be solely derived from the United States Department of Defense or other federal entity acting on behalf of such department.