Charging Ahead: Progress on King County Metro’s First 100% Zero-Emissions Bus Base

Construction of King County Metro’s full-scale electric bus charging base is well underway. As a continuation of our project work and partnership with King County, the McKinstry team is sharing photos and a new video of the current progress at Tukwila Base, located just south of Seattle.

The 544,000 sq. ft. charging and maintenance site at Metro’s South Campus will accommodate 120 battery-electric buses (BEBs). Crews broke ground on the agency’s first 100% electric bus base in March 2024 following the success of a smaller-scale pilot facility on the same campus. The county has set a goal to achieve a 100% zero-emissions fleet by 2035. Tukwila Base will serve as a prototype for the future countywide electric bus deployment plans and base electrification. It will also act as a training center for King County staff and maintenance. In addition to helping the county meet its emissions and electrification goals, Tukwila Base aims to improve air and noise pollution by eliminating unsafe vehicle emissions and loud, fuel-powered engines. This project is bolstered by a $1M grant and $5M in incentives from the Inflation Reduction Act, underscoring the county’s commitment to a sustainable future.

The facility will include 123 BEB pantograph chargers. The electrification project required comprehensive design and site development including the installation of new primary electrical services, communication duct banks and civil/structural/electrical components for charging infrastructure.

Construction is now about 70% complete. McKinstry expects to finish its portion in August 2025. Metro is planning a soft launch from Fall 2025 to Spring 2026 to focus on site transition, process and procedure checks and expanding workforce training. Official operations are expected to begin in the second half of 2026.