抄録
Among the advantages of bus service it is held to have a small unit of, carriage and great flexibility. However, the bus is at a disadvantage (both in cost and speed) where traffic is heavy. Oku-izu, the southern part of Izu peninsula, is a mountainous district in which traffic is rather light, but, since there are no railways, bus service is comparatively well utilized there (Fig. 1).
The writer has studied bus transport of the inhabitants of Oku-izu. Fig. 2 shows the monthly frequency of trips by bus per family in each community. There are two “ordinary regional centers” (the fourth order) and several “service villages” (the fifth order) according to F. H. W. Green's classi-fication. The centers of the fourth order are Shimoda and Matsuzaki. Pas-sengers carried by bus converge on these towns. In order to analize this phenomenon, the writer adopted the following formula
_??_
Fig. 3 shows the rates of convergence for Shimoda and Matsuzaki. The relationship between the frequency of convergence and the distance to the centers are shown in Fig. 4. The following formula may be deduced: y=ax-b, where y=frequency, x=distance (kin), and a=?. In the surround-ing area of the centers, the value of (b) has been determined as
Shimoda…… b=-0.91 Matsuzaki……b=-0.27; and in a remote area, Shimnoda……b=3.32, Matsuzaki……b=-1.73.
In a mountainous region such as Oku-izu, the application of the PA RETO-equation must be divided into two parts: One should be applied in the district surrounding a center within which the rural-urban interaction is strong, while the other should be applied in remote districts where such interaction is weak.
