Cost-Efficient Urban Areas Minimising the Connection Costs of Buildings by Roads: Simultaneous Optimisation of Criteria for Building Interval and Built Cluster Size

Although methods based on bottom-up approaches to delineating urban areas have been developed by focusing on the locations of buildings and road networks, they fail to account for the relationship between the delineated urban areas and the average total management cost of the road networks connecting the buildings. Focusing on building locations, a two-step method is proposed: clustering buildings with intervals that are shorter than a criterion, rc, before delineating built clusters that are bigger than a criterion, mc, as urban areas. Although rc has been optimised in the literature, rc and mc have not simultaneously been offered as optimal solutions. This is the motivation for answering the following question: how can we simultaneously optimise rc and mc to minimise the average total management cost (per building)? The study’s main conclusions are that: (1) there is an rc and mc pair that can minimise the average total management cost and delineate optimal urban areas; and (2) in the empirical study region (Chiba prefecture), the optimal rc and mc are 48 m and 42, respectively. Such optimal urban areas are expected to provide urban planners with a norm that can be compared not only with current but also with future images of urban areas.