King County is taking a major step toward a zero-emissions future with the near completion of its Tukwila Base—the region’s first 100% electric bus base designed to house and charge 120 battery-electric buses (BEBs).
In a recent event, King County Executive Shannon Braddock, Metro General Manager Michelle Allison, and Executive Climate Director Marissa Aho were joined by King County Metro’s Zero Emission and Sustainability Teams to highlight the project’s progress.
“Tukwila Base is one example of King County’s commitment to cutting pollution, taking climate action, and making our communities cleaner and healthier,” said Executive Shannon Braddock. “Powered by the hydroelectric energy of our region, this base is quickly becoming a national and international model for clean energy facilities.”
King County Metro General Manager Michelle Allison emphasized the historic milestone:
“Our new battery electric buses aren’t just cleaner and quieter—they represent our commitment to healthier communities and a better ride for everyone. By choosing transit, you’re helping shape a more sustainable future for your neighborhood.”
The massive 544,000-square-foot facility includes maintenance buildings and an extensive network of EV chargers capable of supporting 120 BEBs. The base will also service zero-emission support vehicles like electric sedans and utility carts, all powered through a new charging system installed at the adjacent parking garage.
Tukwila Base stands out not just for its size but also for its green design.
Features such as lighter-colored concrete to reduce heat islands, water-efficient landscaping to minimize irrigation needs, and energy-saving construction methods have earned the project platinum status under the county’s Sustainable Infrastructure Scorecard, in line with the Green Building Ordinance.
Testing of the infrastructure is scheduled to start soon as the first GILLIG electric buses arrive this fall.
During the testing phase, Metro will focus on procedure validations, workforce training, and operator practice sessions to ensure smooth full-scale operations.
The Tukwila Base is expected to become fully operational by spring 2026, marking a significant leap forward in King County Metro’s goal to operate a completely zero-emission fleet.
