In this paper we propose a method for measuring the area of attainable region from a given railroad station over the Tokyo metropolitan area in which railroad network is well developed. By calculating time distance between arbitral two stations using railroad network databases for 1960, 1980, and 2000, changes in the area of attainable region are used as a measure for advantage of the given place. We reveal that the growth of railroad network and the introduction of express train systems have affected not only on the reduction of travel time but also on the formation of multinucleated urban structure.
