Factors influencing the adoption of carpooling in Switzerland: A differentiation between platforms, family and friends and colleagues

• Cluster analysis of 5,000 + Swiss households identifies five distinct groups. • Evidence shows environmental affect and values impact cluster affiliation. • Differentiates carpooling by type (platform, friends/family, colleagues) and role. • Provides tailored recommendations to boost carpooling adoption for each group. Particularly in developed countries, passenger car occupancy rates are low. Increasing car occupancy rate would reduce the number of vehicles on the road, thus reducing negative impacts from car use such as emissions, congestion, space occupation, accidents and, overall, lead to a more efficient transport system. This paper explores the socio-psychological factors influencing the likelihood of Swiss residents opting for carpooling, whether in the role of a driver or passenger, and organized either through a platform, with family members and friends, or colleagues. By conducting a cluster analysis with over 5,000 respondents from the French- and German speaking population of Switzerland, we found four groups that use carpooling: 1) traditional carpoolers who carpool with family, friends and work colleagues, 2) family and friends-focused carpoolers who use it mostly as a driver, 3) family and friends-focused carpoolers who use it mostly as a passenger and 4) carpooling platform-oriented users. We provide policy and practice-relevant recommendations for carpooling tailored to each of the identified groups based on socio-economic and mobility characteristics, as well as attitudes and values.