SEATTLE—Sound Transit faces rapidly escalating costs in nearly every area of its work, and as part of its Enterprise Initiative to develop a comprehensive process to address this long-term financial challenge, the agency wants to public feedback to evaluate different approaches to updating the ST3 System Plan with a 5-minute survey.
The agency currently estimates that it will need approximately $34.5 billion to cover the funding gap over the next 20 years to deliver the voter-approved Sound Transit 3 program. ST3 includes light rail extensions to West Seattle, Ballard, Tacoma, Everett, South Kirkland, Issaquah, and much more.
Sound Transit’s updated “bottom-up” cost estimates in August and September 2025 revealed dramatic capital cost growth of $14 billion to $20 billion in 2025 dollars — or $22 billion to $30 billion in year-of-expenditure terms — across multiple Sound Transit 3 projects.
The West Seattle Link Extension ballooned from $4.2 billion in the finance plan to between $7 billion and $7.9 billion. The Ballard Link Extension climbed from roughly $11.9 billion to between $20.1 billion and $22.6 billion. Combined, the two lines exceeded $30 billion before adjustments.
During a board retreat held March 18, 2026, in Tacoma, Sound Transit staff presented three scenarios for closing the gap. All three approaches involved scaling back or shortening key projects, including the Ballard light rail extension, with trains potentially stopping at Seattle Center or Smith Cove instead of the originally planned terminus. The board also approved a 1% annual property tax increase in October 2025 and explored additional tools such as fare gates and carbon credits to boost revenue.
Construction defects on the I-90 floating bridge created one of the most significant setbacks in the Sound Transit 3 program. During construction of the East Link Extension, contractor Kiewit-Hoffman installed thousands of defective concrete plinths—the raised blocks that support the light-rail tracks. Issues with incorrect heights, voids, poor consolidation, failing mortar pads, and faulty fasteners first appeared in 2019 and escalated through 2022.
After initial repair attempts collapsed, Sound Transit ordered the complete demolition and reconstruction of approximately 5,400 to 6,000 plinths in 2022.
The plinth crisis repeatedly pushed back the opening of the Crosslake Connection that links the east and west sides of the 2 Line. Kiewit-Hoffman filed claims seeking roughly $184 million for the extra work, extended contracts, and related delays. Sound Transit increased the East Link project budget and drew down contingency funds to cover the fixes.
The Sound Transit Board is working to reduce the impact of what they characterize as historic inflation, tariffs, labor shortages, supply chain disruptions, and other factors on its ability to plan, build, and deliver transit to the region.
Sound Transit staff will synthesize survey responses and share them with Board members in early May, combining this feedback with other input received through email and in-person events into a comprehensive engagement report prior to the May 28 Sound Transit Board meeting.
Preliminary discussions about a potential Sound Transit 4 (ST4) have taken place, but remain in the very early conceptual stages.
Link to Sound Transit survey: https://bit.ly/41AxcmP
Author: Mario Lotmore
