Contiguity of underutilized lands: Dynamic simulation taking their temporary uses into account

In Japan, shrinking densely built-up cities face the dual issue of lacking open spaces and increasing underutilized lands, such as vacant lots, lots with vacant houses, and parking lots. These unused land patches can be temporarily repurposed as open spaces for evacuation and recreation. However, identifying such clump is methodologically challenging. To address this issue, lot geometry is utilized. The study thus aims to investigate the frequency and size of contiguous underutilized lands, called the contiguity of underutilized lands, at a specific time point and under their temporary uses. A densely built-up area in Kobe city, Japan, was selected for the empirical case study. A comparison with simulation results shows that the observed static contiguity of underutilized lands tends to be more substantial than a uniformly random distribution. It shows a certain feasibility of a temporary use policy conducted in the case site. Specifically, when considering the temporary uses of underutilized lands, the maximum area of contiguous temporary open spaces is 583 m2, meeting the area requirement for a redevelopment project in Kobe. Utilizing parking lots can further extend the maximum area up to 945 m2. Nevertheless, policy makers need to promote the joint development of privately owned lots facing a wide roadway, as these are unlikely to become temporary open spaces. This study contributes not only to providing new methods for land use change simulation using lot geometry to analyse the contiguity of underutilized lands under their temporariness but also to demonstrating the feasibility and limitations of a temporary use policy.