Abstract
Building density and distances between adjacent building walls are the primal indices for evaluating fire spreading risk. In the literature, however, the relationship between building density and the statistical distribution of their distances has not investigated theoretically. In this article, the probability density function of distances between adjacent building walls is derived with some assumptions; and applied to drive the probability density function of fire spreading risk for each pair of building construction in a district, by extending Aoki's fire spreading probability function. Since their parameters mainly consist of building density and building coverage ratio, it is possible to evaluate policy effect (e.g. decreasing building density, building coverage ratio or improving building construction from wooden to fireproofed one) on fire spreading risk reduction.
