The activity-based approach, developed during recent decades, enables the development of activity measures that can overcome the drawbacks of conventional approaches. The concept of `space-time prism' illustrates what areas or spaces can be reached, given pre-defined time constraints. The `PESASP' model' enumerates the possible paths between two specified locations, given activities to be performed and physical environmental constraints. To overcome the model's disadvantage of not allowing for people's behaviour, this paper introduces a concept of expected maximum utility of alternative activity schedules. After introducing these basic concepts, it discusses how to define a utility function of an activity schedule. According to the decision structure assumed, single, sequential, and stepwise choice models of activity schedules can be used. The proposed measure, which is specific to individuals and locations, can be made operational by measuring the activities of people and locations; the resulting mathematical formulae for accessibility are presented. Finally, a general procedure is given forcalculating activity-based measures of accessibility.
Abstract