A wider view of shared transportation: Assessing the socioemotional costs and benefits of sharing in and sharing out

Urban planning scholars and policymakers promote shared mobility as a way to reduce congestion and carbon emissions. When doing so, they primarily stress modes like public transit, carshare, bike-share, and ridehail. These are instances where people share vehicles with strangers via market-based interactions or by using public goods. Yet research indicates that in many countries, especially the USA, a substantial portion of vehicle sharing involves sharing among family members, friends, and acquaintances. Meanwhile, planning scholars emphasize the time-related and financial costs of sharing. This overlooks the importance of the subjective experience of sharing, which actively shapes individuals’ willingness and/or reluctance to share. Despite the significance of these factors, the literature has not adequately addressed them. In this critical review, I synthesize literature from sociology, psychology, economics, and anthropology to provide a holistic view of shared transportation. I then establish a typology of vehicle sharing that differentiates between “sharing in” with known persons versus “sharing out” with strangers. I also examine the socioemotional incentives behind sharing—as well as the impediments hindering it—and their relevance for these categories. The novel sharing typology provides a new lens through which to understand the challenges of addressing barriers to sharing. This debates paper is timely as planners and policymakers confront new trends in shared transportation. The COVID-19 pandemic generated new psychological impediments to sharing. By informing policies to promote vehicle sharing, a better understanding of socioemotional factors may help cities to achieve sustainability and equity goals.