Phase I of the “Chaining Behavior in Urban Trip Making” research project has focused on the achievement of three principal objectives: 

Formulation of a theory of complex trave1 behavior based on a recognition of the full range of interdependencies associated with an individual's travel decisions in a constrained environment.  Development of an operational system of models based on that theory.  Initial empirical verification of the system of models developed. 

The approach advanced in this study is based on a comprehensive theory of individual travel behavior that positions travel in a broader context than in single-trip methodologies. In this approach travel is viewed as input to a more basic process involving activity decisions. A fundamental tenet of this approach is that travel decisions are driven by the collection of activities that form an agenda for participation and, as such, cannot be analyzed on a link-by-link basis. Rather, the utility of any specific travel decision can be determined only within the context of the entire agenda. 

A significant element in the development involves a theory of individual choice set formulation that includes both the effect of environmental/household constraints and that of individual limitations with respect to information processing and decision making. An alternate view of utility maximization and its relationship to decision making is presented in which the utility of a decision is comprised of two components: (1) the outcome of the decision and (2) the decision process itself.