Sound Transit has released its 2025-2030 Transit Development Plan (TDP), providing a comprehensive update on the agency’s public transit services, planned expansions, and financial outlook. This annual report, submitted to the Washington State Department of Transportation (WSDOT), summarizes the status of public transportation systems across the state for the Washington State Legislature.
The plan covers Sound Transit’s current service modes, including ST Express (commuter bus), Sounder (commuter rail), T Line (light rail), and Link (light rail), alongside planned capital expenses for the future Stride bus rapid transit service. Sound Transit is currently seeking public input on the TDP before its adoption, with the Board of Directors slated to approve the plan on August 28, 2025. The agency will then distribute the plan on September 1, 2025, to WSDOT, the Transportation Improvement Board, and all cities, counties, and regional transportation planning organizations within Sound Transit’s operating area.
The plan outlines significant capital investments, including the final acceptance of 152 Siemens light rail vehicles (LRVs) in 2025 and an additional 10 in 2027. Major facility openings include parking garages at Auburn and Kent Stations in 2025. The report also details planned operating changes through 2030, which involve restructuring existing ST Express bus services as new high-capacity transit projects reach completion. Significant expansions expected in 2026 include the full Link 2 Line extending to Downtown Redmond and Lynnwood City Center, and the Link 1 Line extending south to Federal Way with three new stations. Stride BRT service launches are expected in 2028 (S3 Line along SR 522 and S1 Line along I-405 South) and 2029 (S2 Line along I-405 North).