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A healthier King County

Zero emissions is our path to an innovative, sustainable mobility network that our communities can rely on.

Sustainable service

Transitioning to a zero-emissions fleet will eliminate our reliance on fossil fuels. Reducing our emissions now is an investment in a more sustainable future.

Healthier communities

Battery-electric buses cut air pollution and keep noise down, too. We’re introducing battery-electric buses in King County communities most affected by air and noise pollution from transportation.

Leading the charge

We’re on track to be one of the first large transit agencies in North America with a fully zero-emissions fleet—and we take that seriously. We’re committed to sharing our successes and lessons learned along the way.

Metro’s journey to Zero Emissions

Metro’s commitment to climate justice drives every step of our transition to zero emissions. Learn what we’ve already achieved and what’s next.

  • 2004

    Became the first public transit agency in North America to adopt a diesel hybrid fleet.

  • 2015

    Purchased a fleet of 174 zero-emissions trolleys.

  • 2016

    Leased and piloted three battery-electric fast charge buses on routes 226 and 241.

  • 2017

    Committed to transitioning to a 100% zero-emissions bus fleet powered by renewable energy.

  • 2018 to 2019

    Leased and piloted 10 battery-electric buses from three different manufacturers.

  • 2020

    Celebrated the retirement of our last diesel bus.

  • 2022

    Began Transit System Electrification Planning to inform technical conversion efforts.

    Launched South Base Test Facility to pilot new charging technologies and start battery-electric bus operations serving up to 22 routes.

  • 2023

    Purchased the last 13 hybrid coaches for RapidRide. All 40 battery-electric buses are now serving South King County. Moving forward, Metro will only purchase battery-electric buses.

  • 2025 to 2026

    Open Interim Base at South Campus, fully equipped to service 120 battery-electric buses.

  • 2026 to 2028

    Open five opportunity charging locations at Kent/Des Moines Link Station and Burien, Kent, South Renton, and Federal Way transit centers.

  • 2028

    Open South Annex Base, Metro’s first Living Building Challenge certified base that will house 250 battery-electric buses.

    Restore two portions of Riverton Creek at South Annex Base to support salmon habitat.

  • 2028 to 2035

    Construct charging infrastructure at the remaining six existing bases and continue to implement opportunity charging.

  • 2035

    Reach zero emissions goal for all modes of transit: Access paratransit, Water Taxi, rideshare, buses, and Metro Flex.

We’re on our way

Our path to a zero-emissions fleet is exciting and rewarding—and it will take time and resources. We’re committed to anticipating challenges before they arise and approaching the work with intentionality and care. We invite you to come along with us.

Our zero emissions resources

Metro will only meet our goal of zero emissions by 2035 by facing challenges head on. To do this, we are piloting programs and testing environments, and actively engaging with industry leaders, peer agencies, and the private sector to learn and share our experiences.

Below you’ll find technical documents, feasibility studies, climate reports, and other information that has guided our journey to zero emissions.

King County Metro Zero Emission Bus Fleet Transition Plan (2022)

This document outlines Metro’s strategy for deploying zero emission buses and chargers as well as transitioning Metro’s seven bases to support zero emission buses by 2035. This plan is required by the Federal Transit Administration (FTA) in order to be eligible for the FTA Low or No Emission Grant Program.

King County's Strategic Climate Action Plan (2020)

This plan is a five-year blueprint for County climate action, integrating climate change into all areas of County operations and work with King County cities, partners, communities, and residents. The SCAP outlines King County’s priorities and commitments for climate action to residents and partners. Specifically, the SCAP created a commitment for King County Metro to transition to a zero‐emission fleet powered by renewable energy by 2035 to eliminate greenhouse gases emitted by Metro’s bus fleet.

Puget Sound Energy (PSE) Transportation Electrification Plan (2021)

This plan, created in response to the Washington state legislature’s House Bill 1512, is a strategic framework for launching new electric mobility programs under PSE Up & Go Electric in the coming years. Some of these programs will support public fleets, like King County Metro, by providing planning assistance, cost estimates, make-ready infrastructure, and other incentive programs.

Seattle City Light Transit Electrification

This plan is a result of the Washington state legislature’s House Bill 1512, which enables electric utilities to incorporate transportation electrification into utility modernization. During the development of the plan, community outreach showed that electrifying public transit was the top priority of Seattle’s BIPOC, immigrant, refugee, and low-income communities who experience the most harm from vehicle emissions. In response Seattle City Light has developed close partnerships with transit agencies (such as King County Metro and Sound Transit) working together to co-plan for the long-term electrification of Seattle’s public transit needs.

Battery Electric Bus Implementation Report (2020)

This report outlines the steps needed to transition to a zero emission bus fleet, which include procuring battery-electric buses, constructing new facilities, setting charging standards, partnering with utilities, and training the workforce to operate and maintain this new vehicle technology. This report was a precursor to the King County Metro Zero Emission Bus Fleet Transition Plan that was finalized in 2022.

Charging Forward: Evaluating Public-Private Partnerships for Electric Bus Base Conversion to Support a Zero-Emission Fleet

The University of Washington (UW) Mobility Innovation Center collaborated with King County Metro to evaluate whether a public-private partnership (P3) model would be beneficial to a zero emission bus base conversion compared to traditional construction delivery methods. The final report includes a P3 decision-making framework and screening tool, a P3 RFP process map, P3 RFP best practices, and an evaluation of KCM’s opportunity to engage in a P3 using the tools developed through the project.

King County Auditor’s Office Bus Electrification Best Practices Review (2020)

This document is a review of best practices for transit bus electrification. This report summarizes key areas that Metro should include in its planning, and county decision-makers should consider as part of oversight of electrification efforts, including: evaluating the impacts of electrification and service expansion/reduction on GHG emissions; tracking and reporting on changes in key inputs and assumptions to assess how they affect the projected cost of electrification; and developing and documenting plans for service, capital project and charging infrastructure, workforce, fuel, and finances.

Metro's report on Feasibility of Achieving a Carbon-Neutral or Zero-Emissions Fleet (2017)

This report responded to Motion 14633, in which the King County Council requested an assessment of the feasibility of achieving either a carbon-neutral or a zero emission Metro vehicle fleet. Several alternatives were evaluated and the assessment considered service needs, costs, necessary supporting systems, environmental results, and social equity benefits. The report ultimately recommended that Metro should transition to a zero-emission bus fleet powered by renewable energy, and focus early deployment of zero-emission buses in the communities that are most vulnerable to air pollution.

Zero-Emission Bus Evaluation Results: King County Metro Battery Electric Buses (2018)

This report summarizes the experience and results from King County Metro’s battery electric bus demonstration which took place from April 2016 through March 2017. FTA collaborated with the U.S. Department of Energy (DOE) and DOE’s National Renewable Energy Laboratory (NREL) to conduct in-service evaluations of advanced technology buses developed under its programs. King County Metro was selected as a participant in this program because the agency was an early leader in testing battery electric buses.

King County Metro South Base Test Facility Charger Summary (2024)

This document is a summary of Metro’s South Base Test Facility electric bus chargers and their technical specifications.

King County Metro Zero Emission Bus Summary (2024)

This document is a summary of Metro’s current fleet of zero emission buses and their technical specifications.

Contact our team

This program or project is supported with funding from Washington’s Climate Commitment Act.