Zero Emissions Bus Program

More Electric Buses are Coming to San Diego

On September 17, 2020 the MTS Board of Directors approved the agency’s Zero Emission Bus (ZEB) transition plan to get the bus fleet to all zero emissions vehicles. The plan helped fast track the purchase of zero emission vehicles (ahead of the state mandate to start purchasing vehicles in 2023), including the agency’s first 60-ft articulated electric buses. Beginning in 2029, 100% of new bus purchases will be zero emission buses, with the goal for full transition by 2040. 

MTS currently has thirteen electric buses in service. 

Transition Plan

Electric buses expanded throughout San Diego County! Look out for the electric buses around San Diego County as we progress to a 100% zero-emission bus fleet.

Throughout the program, buses will rotate to different routes across the system. The frequent rotation will give more riders the opportunity to ride the new vehicles, and will allow MTS to continue monitoring the vehicle/battery performance on a variety of route topographies, distances, times of day/temperatures and more. 


On October 19, 2017, the MTS Board of Directors unanimously approved a multi-year Zero Emissions Bus (ZEB) Pilot Program. The decision builds upon MTS’ strong track-record of operating one of the cleanest public transit fleets in the United States.

Currently, the entire MTS fleet of 40-foot and 60-foot buses use Compressed Natural Gas (CNG), which is one of the cleanest and most affordable fuels available. The agency purchases renewable biogas for its entire fleet, further reducing the carbon footprint of MTS buses. In addition, MTS also operates 130 zero-emission light rail cars.

The nearly $13 million Pilot project was designed to support MTS in complying with the California Air Resources Board’s (CARB) Initiative Clean Transit (ICT) regulation, and to better understand the technology as it operates within MTS's jurisdiction, and develop a transition plan/roadmap to 100% ZEB transition. The pilot ended December 2021.

The ICT requires that all California transit systems transition to ZEB technologies by 2040. MTS brought its draft plan to the public in summer 2020 (view the public workshop and Q&A). Following that meeting, the plan was updated to fast-track more electric vehicle purchases in 2021 and 2022, prioritize vehicle rollout in disadvantaged communities and more. The MTS Board approved the agency’s updated transition plan and CARB's rollout plan in September 2020, which CARB then approved the rollout plan in December 2020. 

About the Pilot Program

MTS’ ZEB Pilot project assisted in providing an analysis of how ZEB technologies operated for MTS’ transit system, and assisted in determining the longer term impact on MTS with for the new ICT regulation. The ZEB Pilot Program included:

  • Partnered with the consultant Center for Transportation & the Environment (CTE) that had experience and technical expertise in analyzing and deploying zero emissions buses and related technologies.
  • Electric bus procurement 
  • Operation and data collection of the electric buses in MTS service area for a period of up to two years (ended December 2021)
  • Detailed analysis and reporting of cost and performance, identification of infrastructure needs and development of a roadmap from pilot to full deployment of ZEBs.

In the partnership with CTE, MTS developed the scope, design and requirements for the ZEB program. In addition, CTE assisted MTS with oversight of the pilot implementation, operation, analysis and reporting ZEB performance challenges and successes. The initial pilot included  eight (8) Battery Electric Buses from New Flyer Industries and Gillig that included the following deliverables:

  • Modeling, and simulation of routes operating from each of MTS’ depots
  • Infrastructure upgrades to support charging infrastructure and/or fuel cell technologies
  • Grid and electricity capacity and consumption analysis
  • Training requirements
  • Operation data collection, monitoring, and analysis
  • Analysis of operational and capital cost components

Zero Emissions Bus Program Project Scope

The MTS ZEB Program began phasing electric bus deliveries that started with the Pilot in October 2019.

The ZEB program links below will continually be updated throughout the progress of MTS's transition to a 100% zero emission fleet. 

  • Bus Procurement
  • Charging Infrastructure
  • Project Budget
  • Project Schedule
  • Data and Analysis
  • Informational Resources
Project Schedule
Bus Procurement
Program Budget
Charging Infrastructure
Informational Resources