Behavioural nudging for greener travel: A discrete choice experiment in the Greater Toronto Area

Environmental management through greenhouse gas (GHG) emission mitigation strategies is a collective responsibility shared by governments, communities, and individuals. Vehicular traffic is one of the leading causes of GHG emissions. Therefore, accelerating the shift from private vehicles to greener alternatives is crucial for achieving carbon neutrality. This study conducts controlled stated preference (SP) choice experiments on travellers' mode choices to nudge sustainable travel behaviours. The experiment aims to provide a quantitative understanding of the effectiveness of nudging for greener behaviour through environmental externality information (GHG emissions) and self-interest information (health implications). The SP experiment was conducted in the Greater Toronto Area, Canada, and had 606 valid samples. An error-component mixed logit model is empirically estimated to capture respondents' behavioural changes during various experiment stages. Based on parameter estimation results, the study also reports the Value of Greener (VOGer), defined as the willingness to pay for comparative GHG emission reductions achieved through greener travel modes. The study finds that the design of nudging interventions plays a crucial role in maximizing individuals’ VOGer. Travellers simultaneously aware of environmental and health-related implications are more likely to use greener travel modes (e.g., transit, biking, and walking).