Application of Space-Time Prisms for the Measurement of Accessibility

The space-time prisms envisioned by Hägerstrand enclose the locations a person can reach by taking into account various time constraints. This concept has been applied on occasions to measure accessibility. It was argued that the potential of applying this approach in spatial analysis was limited by data availability and computing power. Taking advantage of technological advances, a procedure utilizing a Geographic Information System (GIS) is developed to locate facilities within space-time prisms. Data from Portland, Oregon are applied to demonstrate how the proposed procedure can be used to measure accessibility to health care facilities. The potential of the procedure for measuring accessibility from the activity-based perspective is discussed.