Can electric buses encourage greater public transport use? The role of the green halo effect

The electrification of urban bus fleets is widely promoted as a strategy to reduce emissions and enhance the sustainability of public transport systems. Beyond environmental benefits, electric buses may also influence user perceptions and travel behavior. This study investigates how the introduction of electric buses in Thessaloniki affects both actual public transport usage and intentions to increase future use, adopting a holistic approach that considers both users and non-users. Building on existing electric bus adoption models, we extend the Theory of Planned Behavior (TPB) by introducing the green halo effect, capturing the positive spillover of electric bus deployment on the overall image of public transport. The framework also incorporates green self-identity, attitudes, social norms, and satisfaction-related perceptions. Data were collected through an online survey of Thessaloniki residents (N = 474), including both electric bus users (N = 323) and non-users (N = 151). For users, the model examines changes in usage frequency, while for non-users it analyzes intentions to adopt public transport. Structural Equation Modeling (SEM) is applied to test relationships among psychological constructs and behavioral outcomes, complemented by Necessary Condition Analysis (NCA) to identify critical limiting factors for intended modal shift. Results indicate that for current users, physical ride quality is a necessary condition for satisfaction, while the green halo effect independently increases usage frequency. For non-users, exploratory findings suggest that the green halo effect emerges as the strongest model-based predictor and primary limiting factor for future adoption within this sample, overriding general attitudes toward public transport. These findings highlight the potential of fleet electrification to act as a facilitator for behavioral change regarding increasing public transport use.