Séminaire externe du LAET

Abstract : This article examines whether dynamic social norms can encourage drivers to move away from solo car use. We collected data from 4,500 respondents representative of the French population using a labeled Discrete Choice Experiment conducted in France in July 2024. Respondents were asked to imagine taking a two-hour car trip as a driver and to choose between driving alone and two other shared mobility alternatives. The proposed alternatives – solo driving as the status quo, carpooling and crowdshipping – varied according to additional travel time, monetary reward, trust rating, and expected environmental benefits. Respondents were randomly assigned to a control group or to one of two treatment groups exposing them to a dynamic norm message. The first message used additive framing, emphasizing that an increasing number of drivers are adopting shared mobility alternatives. The second message used subtractive framing, emphasizing that fewer and fewer drivers are traveling alone. Mixed logit estimates indicate that all attributes are statistically significant and have the expected impact. A split-sample analysis shows evidence that dynamic norm messages can shift preferences away from solo driving and make carpooling and crowdshipping more attractive, with subtractive framing exerting a stronger influence than additive framing. These findings highlight the potential of carefully framed normative messages as a complementary policy tool for promoting more sustainable mobility behaviours.