In addition to any other power and authority conferred to a city that is located in a county having a population of more than one million five hundred thousand, a city legislative authority may provide or contract for supplemental transportation improvements to meet mobility needs within the city's boundaries. For purposes of this section, a "supplemental transportation improvement" or "supplemental improvement" means any project, work, or undertaking to provide or contract for public transportation service in addition to any existing or planned public transportation service provided by public transportation agencies and systems serving the city. The supplemental authority provided to the city legislative authority under this section is subject to the following requirements:

(1) Prior to taking any action to provide or contract for supplemental transportation improvements permitted under this section, the legislative authority of the city shall conduct a public hearing at the time and place specified in a notice published at least once, not less than ten days before the hearing, in a newspaper of general circulation within the proposed district. The notice must specify the supplemental facilities or services to be provided or contracted for by the city, and must include estimated capital, operating, and maintenance costs. The legislative authority of the city shall hear objections from any person affected by the proposed supplemental improvements.

(2) Following the hearing held pursuant to subsection (1) of this section, if the city legislative authority finds that the proposed supplemental transportation improvements are in the public interest, the legislative authority shall adopt an ordinance providing for the supplemental improvements and provide or contract for the supplemental improvements.

(3) For purposes of providing or contracting for the proposed supplemental transportation improvements, the legislative authority of the city may contract with private providers and nonprofit organizations, and may form public-private partnerships. Such contracts and partnerships must require that public transportation services be coordinated with other public transportation agencies and systems serving the area and border jurisdictions.

(4) The legislative authorities of cities that are participating jurisdictions in a transportation benefit district, as provided under chapter 36.73 RCW, may petition the transportation benefit district for partial or full funding of supplemental transportation improvements as prescribed under RCW 36.73.180.

(5) Supplemental transportation improvements must be consistent with the city's comprehensive plan under chapter 36.70A RCW.