Tennessee Code Title 54. Highways, Bridges and Ferries § 54-9-124

(a) All work of grading, macadamizing, concreting, bridge building, etc., shall be let to contractors by the commissioners. It shall be their duty to advertise the letting or lettings in one (1) or more newspapers published in the county and otherwise as their judgment may direct, and receive sealed bids for the work.

(b) They shall adopt, not later than one (1) week after the time set for opening the bids, the bid of the lowest responsible bidder, if in their judgment to do so would be to the best interest of the county and taxpayers.