Implications of a cluster-type compact city design for accessibility in the suburbs of Toyama City: Simulations in the fuchu area

Abstract

Recently, some cities have adopted urban policies based on a compact city design to facilitate accessibility mainly for the mobility-impaired in Japan's aging society. The city of Toyama developed a "cluster-type" compact city model and suggested two main measures in the city master plan established in 2008 1) improvement of public transportation connecting the city center and local subcenters; and 2) concentration of the population in the target area along public transportation lines from suburban areas. The aim of this study was to analyze the effects of those measures on accessibility to facilities used in daily life (the central railway station, general hospital, shopping center, and supermarket) and determine their implications for urban policy. Accessibility, as represented in terms of time-distance to the nearest facilities, was measured based on road network analysis and bus timetables in the Fuchu area, a suburban area of Toyama. The results showed at the level that most (more than 90%) of the population would be able to reach those facilities. Simulations were conducted for 1) greater frequency of bus transportation and 2) migration into the target area. The major findings were as follows. 1) Accessibility could be substantially improved if bus frequency were increased under five-fold or the rate of migration were greater than 50%. 2) When both simulations were manipulated simultaneously, trade-offs occurred between the contribution of each measure to accessibility. 3) Accessibility for people aged 65 years and older improved relatively well because the ratio of senior citizens is high in peripheral areas. As implications for urban policy on a cluster-type compact city, a short-term aim is to increase transportation frequency with the migration of the mobility-impaired population like senior citizens. A significant long-term goal is to concentrate the population to improve accessibility.