(a)

(1) Except as provided in subsection (b), any metropolitan government of a population of not less than two hundred thousand (200,000), according to the most recent federal census, or any combination of local governments, including metropolitan governments, adjacent counties or municipalities in adjacent counties, having a combined population of not less than two hundred thousand (200,000), according to the most recent federal census, may create a regional transportation authority in the manner provided in this part.

(2) The governing bodies of all creating municipalities for a proposed new regional transportation authority, upon a determination that there is a public purpose, a public and governmental function for the services a regional transportation authority may provide and that the public convenience and necessity requires the creation of a regional transportation authority, may adopt a joint resolution so declaring and creating an authority, which resolution shall designate the name and principal office address of the authority. A certified copy of the joint resolution bearing the signatures of each of the creating municipalities shall be filed with the secretary of state and with the commissioner of transportation; and upon adoption and filing, the authority shall constitute a body politic and corporate, with all the powers provided in this part.

(3) Using the process described for creation in subdivision (a)(2), additional metropolitan governments, counties or municipalities may join an established regional transportation authority so long as such entity is part of a county that is adjacent to the existing boundaries of a regional transportation authority and accepted into the authority with at least a simple majority vote of acceptance by the board of the authority.

(b) The regional transportation authority of Middle Tennessee shall continue to operate as a regional transportation authority under part 1 of this chapter, but may, by a simple majority vote of its governing board, assume and have the authority to exercise the powers, duties and functions of a regional transportation authority under this part in addition to powers authorized in part 1 of this chapter; provided, that the continued participation of each local government in the regional transportation authority of Middle Tennessee shall be ratified by a vote of its local legislative body. The vote shall take place within the timeframe established by the board of the authority, but not less than sixty (60) days from the date on which the vote is taken to assume the powers, duties and functions of a regional transportation authority under this part.