UC Davis Institute of Transportation Studies

The California Air Resources Board (CARB) is considering regulatory changes that would require an increasing share of transit buses to be zero-emissions by 2040 to mitigate transit’s contribution to local air pollution and greenhouse gas (GHG) emissions. Battery electric buses (E-bus) are expected to be the primary technology adopted to achieve this policy goal. While a transition to E-buses may support emissions reductions targets and provide other benefits for urban areas, a transition to electricity from conventional liquid and natural gas fuel buses could also create new costs and uncertainties for transit agencies. Resource-constrained transit agencies must consider trade-offs between service coverage, frequency, and operating expenses against investments in new technologies. This research explores how bus electrification will impact these costs by assessing the total cost of ownership (TCO) using a probabilistic approach. The goal of this report is to identify and assess the key drivers of electric bus adoption costs, characterize uncertainty in forecasting agency transition costs, and provide an approach to support agencies’ assessment of strategic investments in new vehicle technologies. This report specifically considers two replacement periods, the current and next replacement for each agency, across several combinations of bus size and powertrain. The report also considers how agency size, operations, and route structure might affect agency adoption costs. An estimate for how state-wide replacement costs might change between now and 2030 is also provided.