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MAPPING OF TIME DISTANCES BETWEEN PRINCIPAL CITIES IN JAPAN

1981; Association of Japanese Geographers; Volume: 54; Issue: 11 Linguagem: Inglês

10.4157/grj.54.605

2185-1735

Takafumi Yoshimoto,

Geographic Information Systems Studies

The map representation is one of the most important methods used in geography. In many cases, maps are projected onto two-dimensional planes. Considering the problem of plotting the distance data for the given n locations, two coordinates are required for each location. Accordingly, the ploblem of mapping the potential structure of interpoint distance in which dimensions are required to be represented spatially, may be solved by that n two-dimensional position vectors are derived from n times n distance matrix. In this study, the mapping of time distance between forty six cities which are the prefectural capitals in Japan is attempted under the assumption that one travels between the cities by the Japanese National Railways only. And, hypothesizing that the potential structure of time distances between the cities may be expressed in a two-dimensional time-space, Tobler's multilateration method for multidimensional scaling is applied. If the hypothesis mentioned above is accepted, the transportation system represented by the National Railways in Japan may be visualized on a two-dimensional map and the possibility of visual consideration in the researches on transportation system is suggested. Investigation of the hypothesis is undertaken as follows: 1. The spatial configurations of cities are reconstructed onto a two-dimensional time-space map, and the profile of the map is interpreted visually. 2. For October 1961 and April 1980, the spatial configurations of cities are analyzed respectively. And according to the time-serial comparison between them, the problems how the transportation system in Japan has developed for these nineteen years are considered. 3. Concerning such problems, the usefulness of Tobler's method is examined. The resulting time-space maps are illustrated in Fig. 4. According to the evaluation of a goodness-of-fit, it may safely be asserted that the input data of time distances are sufficiently reconstructed on the two-dimensional Euclidean space, E2. On the other hand, it can be regarded that Tobler's method is sufficiently useful on the condition that the input data of interpoints are metric and that the space in which the points are reconstructed is E2. Therefore, the possibility of visualization of the complicated data may be suggested. According to the time-serial comparison of the time-space maps, the time distances have been decreasing all over the country. Especially the Shinkansen, the trunk line, with very highspeed, of the Japanese National Railways, has much affected to shorten the time distances. In terms of a goodness-of-fit for each city, the well-fitted cities are distributed along the main rail lines on the Pacific coast (i.e. the Tokaido and Sanyo Lines). Conversely, for the cities located in the other areas such as the coast of the Japan Sea, the inland areas and Shikoku, and also in the peripheral areas (i.e. Hokkaido, Tohoku and Kyushu), a goodness-of-fit is poor.