(a) The governing body of a principal municipality, the commissioners court of the county of the principal municipality, or both of these bodies, from each subregion of a metropolitan area, may agree to initiate the process to create, by a motion of the body, a regional transportation authority to provide public and complementary transportation services in the area. The principal municipality, the county of the principal municipality, or both entities, in each subregion, may become the creating entity.
(b) The governing body of a principal municipality, the commissioners court of the county of the principal municipality, or both of these bodies, from any subregion of a metropolitan area, shall initiate the process to create a regional transportation authority to provide public and complementary transportation services for a metropolitan area on receipt of a petition requesting creation of an authority signed by at least five percent of the registered voters of the principal municipality, county, or both, as appropriate. The entity to which a petition is presented has the primary responsibility for initiating the authority within a subregion. The principal municipality and the county of the principal municipality of any subregion, however, may by agreement share the responsibility or shift it from one to the other.

(c) If one subregion establishes an authority, the remaining subregion may establish a separate subregional authority as provided by this chapter. This subsection does not apply to an authority created by a contiguous municipality.
(d) The governing body of a contiguous municipality on its own motion may, and on presentation of a petition requesting the creation of a subregional authority and signed by at least five percent of the voters of the contiguous municipality shall, initiate the process to create a subregional authority:
(1) as an alternative to participation in a regional transportation authority;
(2) if the creation of a regional transportation authority in which the contiguous municipality could participate is not confirmed;
(3) if the contiguous municipality withdraws from a regional transportation authority and:
(A) the regional transportation authority in which the municipality had participated is abolished by act of the legislature or by a vote of the voters of the entire service area; or
(B) the sales tax authorized to be collected by the regional transportation authority of which the contiguous municipality was formerly a member is modified in a manner that would reduce the authority’s annual revenue yield by one-half or more; or
(4) if a regional transportation authority in which the contiguous municipality could participate is dissolved.