Study on the factors to transform underused land focusing on the influence of railway stations in central areas of Japanese Local cities

•In this study, we constructed a GIS database of underused land in 37 Japanese core cities at three time points.•We analyzed the relationship between the changes in underused land area and urban characteristics and the factors to transform underused land into business-use land and residential land with an emphasis on the influence of railway stations.•Small lots of underused land have decreased in central areas, but there is a net increase in underused land in the last 20 years because large areas of underused land.•Outdoor parking lots have a negative effect on the transformation from underused land to business-use and residential land.•If underused land is to be transformed into residential land by adopting land-use zone, our findings indicate that the ratio of land within a 0–200m radius from a railway station should be increased. The recent increase in underused land, such as outdoor parking lots and vacant areas, is a serious problem that has led to the decline of central areas in Japanese local cities. To develop these land lots, the distribution of underused land as well as factors to transform these areas must be analyzed. However, the secular changes in underused land are not understood quantitatively, and transformation factors have not been analyzed from the viewpoint of underused lot types. In this study, we constructed a database of underused land using housing maps on GIS. Then we analyzed the relationship between the changes in underused land areas and commercial activity in the central areas of 37 core cities. Finally transformation factors from underused land to business-use and residential land were evaluated with an emphasis on the influence of the proximity to a railway station. Between 1985 and 2005, the results show that small areas of underused land have decreased in central areas, but there is a net increase of underused land. Additionally, commercial activity and population have declined in central areas compared to national trends and the average of core cities. Analyses of transformation factors reveal that outdoor parking lots negatively impact the transformation, but the combination of constructing of railway stations close to central areas and adopting land-use zoning for business-use and residential land have a positive affect on the transformation of underused land.