Beyond Either/Or: The Role of Hybrid Buses in Fleet Transition Planning

As transit agencies navigate advanced transportation technology pathways, hybrid buses offer more than an outmoded detour.

For transit agencies, fleet transition planning rarely follows a straight line.

Across North America, agencies are evaluating and deploying advanced transit technologies to meet operational goals, reduce emissions, and prepare for the future of public transportation. Battery-electric and hydrogen fuel cell buses are increasingly becoming part of those conversations, with many agencies successfully integrating these technologies into service today.

Of course, every transit agency operates within a unique set of circumstances. Fleet age, facility readiness, workforce capacity, service requirements, funding availability, and local operating conditions can all influence the pace and timelines of technology adoption. As a result, fleet transitions are rarely defined by a single technology or a single decision point. Instead, they often involve a series of incremental steps that help agencies build the muscle of experience and prepare, clear-eyed, for future investments.

Consider the hybrid: While in many aspects eclipsed by more state-of-the-art transportation tech, hybrid technologies continue to play an important role in fleet transition — not as an alternative to future transit innovation, but as one of many tools that can help agencies gain operational experience and contribute to industry-wide learning.

“Agencies may consider hybrids when they need to replace buses but are not yet ready to support zero-emission vehicles across all service,” says Mike Hynes, Deputy Director of Transit at CALSTART. “That could include delays in charging infrastructure or utility upgrades, limited hydrogen availability, long or variable routes, extreme temperatures, or service that leaves little time for charging.”

Building Experience Through Real-World Deployment

In the United States today, there are large metropolitan systems operating hundreds of buses, small rural providers serving low-population communities, and everything in between. Some agencies have deployed battery-electric or hydrogen fuel cell buses in sufficient numbers to gain meaningful operational experience and begin realizing benefits in areas such as emissions reduction, energy efficiency, operational cost savings, and vehicle performance. Others are beginning to evaluate advanced technologies for the first time. Many are balancing long-term transition goals with near-term operational realities, including budget constraints and fleet replacement schedules.

For agencies navigating these considerations, hybrid technologies can offer valuable opportunities to build familiarity with advanced propulsion systems and vehicle technologies.

Hybrid deployment allows transit operators, maintenance personnel, planners, and leadership teams to gain firsthand experience with systems that differ from traditional diesel-powered fleets. Agencies can develop new maintenance practices and evaluate operational performance. They can better understand energy management considerations and gain insights that inform future procurement decisions. Perhaps most importantly, experience gained through deployment helps build confidence. The “devil you know” will always have appeal, but experience with another way of operating can be a powerful driver of improvement.

For example, agencies like King County Metro and New York’s Metropolitan Transit Authority (MTA) operated large hybrid fleets before expanding into battery-electric buses. “It would be difficult to say [their] hybrids were purchased specifically to prepare for zero-emission technology,” says Hynes, “but they did give those agencies experience with electric propulsion, high-voltage systems, batteries, regenerative braking, and software-based diagnostics.”

After all, technology transitions are not only about vehicles and infrastructure; they are also about people, processes, and institutional knowledge. The lessons learned through operating hybrid technologies in daily service can help agencies better understand how future technologies may fit within their unique operating environments. This is why real-world experience matters so much.

Deployment’s External Echo

The value of deployment extends beyond individual transit agencies. Every time a new technology is introduced into real-world service, the industry gains valuable information about how that technology performs across different operating environments. Transit agencies generate insights on reliability, maintenance requirements, energy consumption, rider experience, and operational performance. Manufacturers gain feedback that helps refine vehicle design and technology integration. Researchers and technology providers gain a deeper understanding of deployment challenges and opportunities.

Collectively, these experiences power an ecosystem of innovation and continuous improvement. Since its advent, transportation has improved through deployment, evaluation, feedback, and refinement. The broader market benefits when agencies, manufacturers, technology providers, and industry organizations work together to identify best practices and share lessons learned.

According to Hynes, hybrid development helped advance several systems now used in zero-emission buses, including electric traction motors, inverters, battery-management systems, regenerative braking, electric accessories, thermal management, and vehicle-control software. “Transit hybrids were not the only source of those advances, but they gave manufacturers and agencies a place to test the technology in regular heavy-duty service.”

Continued evaluation of hybrid technologies contributes to this process. Deployment experiences help stakeholders understand where technologies perform best, what operational conditions support success, and what considerations should inform future planning and procurement decisions. This type of market learning also supports supply-chain development, workforce readiness, and continued investment in advanced transportation technologies.

In other words, every hybrid deployment contributes knowledge that helps inform the next generation of innovation.

Advancing Understanding Through Demonstration Projects

This kind of iterative learning can happen organically — but it can also be planned.

CALSTART is currently preparing for an upcoming demonstration project focused on hybrid shuttle buses, conducted in partnership with Transit Vehicle Innovation Deployment Centers (TVIDC). TVIDC is a Federal Transit Administration program that provides demonstration and testing facilities to support the evaluation of next-generation public transportation technologies. The initiative is designed to evaluate the readiness and operational suitability for hybrid technologies operating in transit shuttle, circulator, and full-sized bus services.

These projects include real-world pilot demonstrations that will collect data on vehicle performance, reliability, energy use, and maintenance requirements. Researchers and project partners will then analyze deployment considerations, operational impacts, and total cost of ownership to develop guidance and lessons learned that can support future decision-making across the transit industry.

Importantly, these projects are not focused solely on evaluating vehicle performance. They are also intended to generate practical insights that transit agencies can use when assessing technology options and planning future investments. By creating opportunities for real-world testing and evaluation, projects like these help reduce uncertainty and strengthen the industry’s collective understanding of emerging technologies.

One of the biggest challenges facing transit agencies today is making investment decisions in a constantly changing environment. New vehicle technologies continue to emerge, while infrastructure requirements evolve and funding opportunities shift; it can seem like nothing stays the same long enough to make plans around. But demonstration projects provide opportunities to gather objective information about performance, maintenance requirements, operating costs, and deployment considerations before agencies commit to larger investments.

They also create opportunities for peer learning. Transit agencies often benefit most from hearing directly from other agencies that have deployed and operated technologies in service. Understanding what worked, what challenges emerged, and what lessons were learned can help reduce risk and improve future planning efforts.

Through TVIDC-supported projects, participating agencies have opportunities to engage with industry partners, access emerging project findings, and contribute to collaborative discussions focused on technology deployment and operational outcomes. This type of applied learning helps strengthen decision-making while supporting broader industry advancement.

Fleet Transitions Are Not One-Size-Fits-All

Technology adoption strategies are rarely identical. Some agencies may move quickly toward battery-electric deployments. Others may focus on hydrogen technologies. Still others may pursue a combination of approaches based on operational needs and available resources. Hybrid technologies fit within this broader continuum of fleet planning and technology evaluation.

Rather than viewing fleet transitions as an either-or proposition, agencies can benefit from understanding how different technologies contribute to learning, readiness, and long-term planning. What matters most is continued progress, and hybrid buses remain part of a broader ecosystem that supports that progress. Projects like CALSTART’s illustrate the value of creating opportunities for practical evaluation and industry collaboration. By generating real-world data and facilitating knowledge-sharing, these efforts help agencies better understand technology options while supporting continued innovation across the sector.

Hybrid technology may not be the way of the future, nor a relic of the past. It could, however, be part of any given transit agency’s travel plan on a journey of innovation and improvement — wherever they arrive, they’ll be glad they had it along the way.

Have questions about current TVIDC projects or need fleet transition planning support? Connect with CALSTART’s Transit team at transit@calstart.org.