抄録
The formulae to estimate the length of roads in an arbitrary region are to be concerned in this paper. First, we introduce the formula which Koshizuka derived by use of integral geometry. It implies that the length is proportional to the square root of the area of the region multiplied by the number of crossings. Koshizuka's formula is theoretically elegant and easy to use. However, it has been considered to be applicable only if the region is convex. The objective of this study is to argue that Koshizuka's formula is applicable even if the region is non-convex and non-connected. To do so, we introduce the thickness function in geometric probability.
