King County Metro nears completion on electric bus base

King County Metro’s Tukwila Base, its first 100 percent electric bus base, is nearing completion and preparing to start testing the charging infrastructure that will power more than 120 new battery-electric buses (BEB). 

“Tukwila Base is one example of King County’s commitment to cutting pollution, taking climate action, and making our communities cleaner and healthier,” said King County Executive Shannon Braddock. “Powered by the hydroelectric energy of our region, this base is quickly becoming a national and international model for constructing a clean energy facility. The buses of tomorrow are arriving, and this base is ready for its role in reducing carbon emissions.” 

“[King County] Metro’s focus on becoming one of the first large transit agencies in the United States to operate a zero-emission fleet hits another key milestone with the arrival of our two new BEBs and installation of charging infrastructure at Tukwila Base.” said King County Metro General Manager Michelle Allison. “This facility—and the world-class technicians and other transit professionals trained to operate it—are ready to get to work. Our new battery electric buses aren’t just cleaner and quieter—they’re a commitment to healthier communities and a better ride for everyone. By choosing transit, you’re not only helping the planet, you’re also helping to shape a more sustainable future for your neighborhood.” 

The 544,000-square-foot base will include maintenance facilities and charging infrastructure for up to 120 BEBs. The base will also be home to zero-emission support vehicles, including electric sedans and utility carts, all powered by new charging infrastructure installed at the adjacent parking garage. 

King County Metro is also incorporating sustainability into the design and construction of the new buildings at Tukwila Base. The agency says construction currently underway is maximizing Tukwila Base and is designed to reduce energy consumption, and lighter-colored concrete will help reduce the heat island effect. to minimize the need for irrigation. The agency says the features achieve platinum status on the county’s Sustainable Infrastructure Scorecard as required by the Green Building Ordinance. 

The agency’s project team says the charging infrastructure is nearing completion and will be ready for testing as the first GILLIG buses purchased last spring start arriving this fall. During the testing period, King County Metro will focus on procedure checks, testing the charging infrastructure, expanding workforce training and allowing bus operators to practice using the base’s charging systems. 

Tukwila Base is scheduled to begin full operation in spring 2026.