Journal of Geographical Systems

Volume 5 Issue 1 (2003) pp 71-91

Space-time Accessibility Measures:
A Geocomputational Algorithm with a Focus on the Feasible
Opportunity Set and Possible Activity Duration

Hyun-Mi Kim and Mei-Po Kwan

Abstract. Space-time accessibility measures have received much attention in recent years due to their sensitivity to differences in individual ability to participate in activities in space and time. Despite the conceptual attractiveness and robustness of space-time measures, only few attempts have been made to operationalize them to date. Research that seeks to improve space-time accessibility measures is still sorely needed. This study seeks to enhance space-time accessibility measures through developing a new operational method and GIS-based algorithm that better represents the space-time characteristics of urban opportunities (e.g. their geographical distribution and opening hours) and human activity-travel behavior (e.g. delay times, minimum activity participation time, and maximum travel time threshold). The proposed method not only takes into account the number and size of opportunities, but also the possible activity duration at each activity location given its opening hours and the effect of transport network topology (e.g. one-way streets, turn restrictions and over-pass). Incorporating these elements into space-time measures helps overcome several shortcomings of previous approaches to evaluating space-time accessibility.

Key words: Individual accessibility, space-time accessibility measures, space-time constraint, space-time prism, GIS

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