Sound Transit has selected a joint venture between Traylor Bros. and Atkinson Construction as the heavy civil general contractor and construction manager for the upcoming West Seattle Link Extension light rail project.

The joint venture will bring early contractor involvement during the design and pre-construction phases to optimize constructability, manage complex civil risks, and refine cost schedules before major heavy construction begins.

The project spans approximately 4.7 miles, connecting Downtown Seattle to West Seattle's Alaska Junction neighborhood. Major infrastructure features include a dedicated light-rail bridge over the Duwamish River running along the south side of the existing West Seattle Bridge, elevated and tunnel guideways, and new stations serving SODO, Delridge, Avalon, and Alaska Junction. Phase 2 of final design officially began on August 3, 2026, which will advance the light rail line to 100 percent final design through July 31, 2028.

Concurrent with design progress, Sound Transit released its third quarterly report for 2026 detailing compliance with Section 106 of the National Historic Preservation Act under a Programmatic Agreement executed in February 2025. Recent geotechnical and geoarchaeological investigations conducted across the project area identified no new archaeological resources.

Sound Transit is also moving forward on several historic preservation and mitigation commitments along the route:

• Tribal and Cultural History Plans: A revised draft plan interpreting tribally important places in the Duwamish River Valley, alongside a public interpretation plan for the corridor's social and cultural history, will be distributed for review in the fourth quarter of 2026.
• Industrial History Context: A historic context study examining the industrial development of West Seattle and the Duwamish Waterway is currently being finalized, with completion expected by the second quarter of 2027.
• Building Demolition Mitigation: Sound Transit has begun preparing Level 2 documentation for historic properties scheduled to be demolished, which will be submitted to state repositories and made public before building removals occur.
• Subsurface Historic Utilities: Following a July 2026 meeting with consulting parties, Sound Transit is finalizing a memo documenting known historic utilities and establishing protocols for inadvertent discoveries during construction.

The next quarterly progress report on Section 106 implementation is scheduled for release in December 2026.