Transit agencies in the United States are significantly shifting from predominantly fossil fuel–powered vehicles to zero-emission vehicles. While many transit operators are introducing these types of vehicles into their fleets, there are concerns about how to meet agency commitments pragmatically during the transition period. Research is needed to answer questions such as: What are realistic timelines for developing access to necessary electric power–generating capacity? What is the current reliability and availability of service of zero-emission sub-fleets? How can agencies determine the appropriate mix of sub-fleets to meet agency and community expectations during the transition period to stated agency goals? What are the best ways to frame and communicate realistic timelines for long-term procurements to the public? Are there additional uncertainties for shorter buses and cutaways? What are the labor and training transition timelines to prepare the needed workforce? How is competition for charging infrastructure with private vehicles to be handled?

This research should build on but not replicate TCRP Research Report 219: Guidebook for Deploying Zero-Emission Transit Buses (2021). The guidebook is organized into these key deployment phases: providing information and suggestions for assessing needs and requirements, selecting and specifying technology, determining capital costs and funding opportunities, developing and deploying fueling infrastructure, accepting and validating buses to ensure they meet specifications, evaluating training program considerations, establishing operations and maintenance practices, and monitoring and evaluating deployment performance.