SPACE-TIME AND INTEGRAL MEASURES OF INDIVIDUAL ACCESSIBILITY - A COMPARATIVE-ANALYSIS USING A POINT-BASED FRAMEWORK

Conventional integral measures of accessibility, although valuable as indicators of place accessibility, have several limitations when used to evaluate individual accessibility. Two alternatives for overcoming some of the difficulties involved are explored in this study. One is t o adapt these measures for evaluating individual accessibility using a disaggregate, nonzonal approach. The other is to develop different ty pes of measures based on an alternative conceptual framework. To pursu e the former alternative, this study specifies and examines eighteen g ravity-type and cumulative-opportunity accessibility measures using a point-based spatial framework. For the latter option, twelve space-tim e accessibility measures are developed based on the construct of a pri sm-constrained feasible opportunity set. This paper compares the relat ionships and spatial patterns of these thirty measures using network-b ased CIS procedures. Travel diary data collected in Columbus, Ohio, an d a digital data set of 10,727 selected land parcels are used for all computation. Results of this study indicate that space-time and integr al indices are distinctive types of accessibility measures which refle ct different dimensions of the accessibility experience of individuals . Since spacetime measures are more capable of capturing interpersonal differences, especially the effect of space-time constraints, they ar e more ''gender sensitive'' and helpful for unraveling gender/ethnic d ifferences in accessibility. An important methodological implication i s that whether accessibility is observed to be important or different between individuals depends heavily on whether the measure used is cap able of revealing the kind of differences the analyst intends to obser ve.