MULTISTOP-BASED MEASUREMENTS OF ACCESSIBILITY IN A GIS ENVIRONMENT

The opportunities available at a demand location are usually measured as the costs of reaching a specified critical number of facilities fro m that location. This method does not however, account for multistop t rips nor for differences in the diversity of supply at the level of in dividual facilities. In this paper we introduce an alternative measure ment method that overcomes these shortcomings. In this method the prob ability of successfully visiting a specific facility is assumed to be a function of the diversity of supply provided. Trip routes are constr ucted that have an acceptable probability of success. Then, the expect ed costs of travelling the optimum route are determined as an indicato r of spatial opportunities. The proposed method has been implemented i n a GIS environment, using typical GIS data and GIS tools for spatial analysis and display. The results of a case study indicate that the ne w method, compared to current methods, may lead to different evaluatio ns of the level of opportunities at demand locations.