Travel behaviour: theoretical foundations

Travel is a complex socio-economic, spatial-temporal activity. This chapter introduces key theoretical foundations for understanding this complex behaviour. Foundational concepts include: (1) the activity-based nature of travel: we travel to participate in out-of-home activities; (2) travel is a spatial interaction process in which activity participation plays out explicitly over space and requires expenditures of time, money and effort; (3) travel dynamics in which behaviour adjusts within the short-run of daily network interactions and adapts over the long run as attitudes and behaviours evolve; (4) the inherent heterogeneity in traveller’s attributes, preferences and choice contexts requires a probabilistic and disaggregate (individual traveller) theoretical approach. Key theories of travel decision-making that build on these concepts can be divided into two categories: (1) behavioural theories: random utility theory and risk minimization theory; and (2) statistical approaches: entropy maximization and machine learning methods. The chapter concludes with a brief discussion of notable gaps in our current theory that represent desirable avenues for further research.