Accessibility Measurement by the Cumulative-Opportunity Method

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An understanding of multi-dimensional regional structure is indispensable in regional planning. Accessibility is one of the most useful indices. Measures of accessibility are grouped according to method of calculation into three types, namely the network measure (formula 2), potential measure (the measure of population potential-type is formula 3, and measure of potential transportation cost-type is formula 4) and the cumulative-opportunity measure (formula 1). The cumulative-opportunity measure has merits differing from the other two measures because of its method of calculation. The purpose of this paper is to calculate accessibilities for employment opportunities in Fukuoka Prefecture by the cumulative-opportunity measure. The distribution of accessibilities was compared with ones calculated by the other two measures. Afterward, the practical applications of accessibility were examined. The data were obtained from the 1980 Population Census of Japan and the time-distance between each district. The main findings are summarized as follows:1. The distribution of accessibility calculated by the cumulative-opportunity measure expresses clearly regional differences and the effect of complicated traffic routes. Districts with high accessibility are located not only along the Kagoshima-line, Nishitetsu-line and Chikuho-line, but also along the Sasaguri-line, Nippo-line, Chikuhi-line and Kyudai-line. These districts correspond well with the districts in which the indigenous labor force is presently increasing or is expected to increase in the near future. Accordingly, this measure is maybe said to be a tool useful for regional planning.2. The distribution of accessibility calculated by the network measure reflects the traffic network. However, the distribution of accessibility cannot express the effect of the detailed traffic route and the evaluation for regional differences of accessibility becomes insufficient. Accordingly, detailed analysis is impossible with this measure. The distribution of accessibility calculated by the potential measure of potential transportation cost-type is similar to the one calculated with the network measure. The distribution of accessibility calculated with the other type of potential measure, which is the measure of population potential-type, reflects strongly the distribution of employment opportunities. Highly accessible districts correspond to high hierarchical centers and not to the districts in which the local labor force is presently increasing or expected to increase in the near future.3. Accessibility for population distribution of labor force was calculated by substituting the population of the indigenous labor force as an attractor variable. As a result it was concluded that accessible districts are suitable for the construction of new industrial areas and the relocation of businesses from the city centre. To measure the discrepancy between accessibility for employment opportunities and that for the local labor force suggests which important districts are important for regional planning.4. Further, this indicates that accessibility for employment opportunities and population distribution of the labor force by separate occupations could be calculated by taking the population data of individual occupations as an attractor variable.