Causal Relationship Among Travel Mode, Activity, and Travel Patterns

Simple or complex travel patterns, performed as activities, are linked, and various travel modes are used. Individuals try to link several trips as a type of chain to save transportation resources, such as travel distance or time, which consequently produces complex travel patterns. These changes in the urban transportation environment and some studies on activity-based characteristics make it difficult to forecast trips as a result of trip linkage behavior. Two models are established to achieve research objectives. The first is an allocation model for travel modes for activities by the three stage least square (3SLS) estimation method under the restricted conditions. The other is a covariance structure model to analyze direct and indirect effects among latent variables and estimated variables. As a result of 3SLS, the allocation of travel modes is mainly influenced by personal attributes such as gender, education level, and marriage and household attributes, such as the existence of children under 13 years old. In the covariance structure model, it is shown that exogenous estimated variables for personal characteristics explain well the personal latent variable and only household income explains the household latent variable. While the travel behavior latent variable is well effected by travel mode latent variable, it is less effected by the activity latent variable.