Tenn. Code Ann. § 54-5-112: County legislative bodies must authorize payment by counties

No county is to have entered into an agreement to cooperate with the department upon any state or state and federal aid highway project unless the agreement is first authorized by resolution of the county legislative body regularly adopted upon and after submittal to that body by the department of a proposal for the project in proper form, setting forth in detail the proposed improvement with location and routing, the landowners and their respective properties in areas and improvements affected by the project, and, if required, the approximate damages and costs of the project.