(1) The board of a regional transit authority may establish one or more enhanced service zones within a portion of the boundaries of the authority in order to finance system improvements directly serving the respective enhanced service zone or zones. An enhanced service zone must lie entirely within the authority boundaries and must comprise no less than the entire portion of a city or town that lies within the authority boundaries. An enhanced service zone may also include one or more entire adjacent cities or towns and adjacent unincorporated areas, and must contain all or portions of one or more high capacity transportation projects included within an existing voter-approved regional transportation plan. There may also be multiple enhanced service zones encompassing the same city or town, and adjacent unincorporated area.

(2) Before an enhanced service zone may be established, it must first be recommended to the board of the regional transit authority by an advisory committee appointed by the regional transit authority board and composed of board members representing the subarea in which the proposed enhanced service zone is located. The advisory committee's recommendations must include proposed system improvements that benefit the enhanced service zone, to be financed by the excise taxes authorized in subsection (5) of this section, and constructed and operated by the regional transit authority. If the board establishes the recommended enhanced service zone, then the board must submit a ballot proposition to voters within the enhanced service zone at a general or special election for approval of the proposed system improvements and funding sources as provided in subsection (5) of this section. The funding sources may not be imposed without approval of a majority of the voters in the enhanced service zone voting on the proposition. The proposition must include a specific description of the proposed high capacity transportation system improvement or improvements, including speed, reliability, and safety enhancements to the improvements, and the funding sources to be imposed within the enhanced service zone to raise revenue to fund the improvement or improvements. Design and construction of the system improvements approved by the voters of an enhanced service zone may not delay the estimated completion date of high capacity transportation system improvements contained in an existing voter-approved regional transit plan, by more than six months. A regional transit authority may not proceed with the construction of any system improvement or improvements financed by an enhanced service zone prior to providing a report regarding the engineering and financing of each such system improvement to the transportation committees of the legislature that confirms that the system improvement will not delay the estimated completion date of high capacity transportation system improvements contained in an existing voter-approved regional transit plan by more than six months.

(3) The ballot proposition authorized by subsection (2) of this section may authorize improvements that are:

(a) Enhancements to one or more high capacity transportation systems contained in an existing voter-approved regional transit plan. Enhancements include modifications to an existing system's facilities that improve performance characteristics such as speed, reliability, potential for future expansion, and safety or the completion date of the system but do not change the mode or route alignment of the system previously approved by voters, and improvements to service, such as reducing headway times or adding interim bus service;

(b) New rail improvements on alignments that are not contained in an existing voter-approved regional transit plan and connect to the high capacity transportation system;

(c) High capacity transportation system planning for future system expansion within the enhanced service zone; or

(d) A combination of the improvements authorized by this subsection.

(4) Application of RCW 81.104.100 and 81.104.110 are suspended for any ballot proposition submitted to the voters of an enhanced service zone if the improvements only contain enhancements authorized by subsection (3)(a) and (c) of this section.

(5) A regional transit authority may levy and collect within the boundaries of an enhanced service zone one or more of the following voter-approved local option funding sources to finance the proposed improvements within the enhanced service zone:

(a) A supplemental motor vehicle excise tax as provided in RCW 81.104.160(1)(b); and

(b) A commercial parking tax under RCW 81.104.230.

(6) To the extent that system improvements include new fixed rail guideway components of the rail fixed guideway public transportation system within a city with a population of 500,000 or more, such guideway shall be in entirely exclusive rights-of-way and not contain any level traffic crossings with modes not part of the rail fixed guideway public transportation system.

(7) "System improvement or improvements," as used in this section, means additions to or alterations of a high capacity transportation system or rail fixed guideway public transportation system as both are defined in RCW 81.104.015.