Sound Transit, the Puget Sound region's high-capacity transportation system provider, is updating the long-range vision, Sound Move. This update is designed to account for population and employment growth changes in the four-county region since the 1990s. The Phase 2 Plan Update will explore extending light rail and commuter rail lines; adding more regional bus service and facilities like transit stations; increasing hours of operation for all service; and determining the best technologies for moving people throughout the region. Washington State law requires the appointment of an Expert Review Panel in joint concurrence with the Governor's Office, the Chair of the State Legislative Transportation Committee, and the Secretary of Transportation as a condition of the plan update.

The purpose of the Expert Review Panel, as directed by RCW 81.104, is to provide independent review during the development of the plan update so that critical questions are posed and assessed, as well as to guide the preparation of the plan through the panel's review of methodologies and assumptions, and to ensure the assumptions in the study plan are appropriate and reasonable.

The panel's technical review of the plan development is necessary to guarantee that the Sound Transit governing board can make appropriate decisions for Phase 2 Plan investments in the region's high-capacity transportation system.