Social interactions in transportation: analyzing groups and spatial networks

Travel demand is derived from activities that people have to or want to engage in. Work trips have been a primary concern for transportation researchers and an early focus of transportation modeling was on commuting behavior (Ben-Akiva and Lerman 1974; Train 1980). Subsequently, non-work activities, such as shopping or doctor visits, increasingly caught the attention of transportation analysts, and interest shifted from a trip-purpose approach (i.e. work trips) towards scheduled-based travel analysis (Bhat and Koppelman 1999). However, these activity trips all have in common that they still could be modeled without considering social context. The analysis approach of choice behavior was rooted in neoclassical economics assuming methodological individualism of isolated, utility-maximizing agents (Small and Winston 1999). While using the traditional neoclassical tool box, much has been learned about journeys to work and trip scheduling for non-work activities. Early research in intra-household interactions in travel demand modeling focused on coordination of individual daily activity patterns, joint participation in activities and travel, mechanisms for allocation of maintenance activities, and activity location and residential location choice behavior (Scott and