Spatial Patterns of Bridge Deterioration and Municipal Maintenance Potential for Municipality-Managed Bridges in the Chubu Region of Japan

Aging bridge infrastructure poses a growing challenge for Japanese municipalities under population decline, fiscal constraints, and shortages of technical personnel. This study analyzes municipality-managed bridges in the Chubu region of Japan by integrating bridge inspection records with demographic, fiscal, technical staffing, and regional-condition indicators. Bridge deterioration severity for 237 municipalities was evaluated, and its spatial structure was examined using Global Moran’s I and local indicators of spatial association (LISA), which respectively indicate whether similar deterioration levels are regionally clustered across the study area and where local clusters or spatial outliers occur. The results showed significant positive spatial autocorrelation, indicating that deterioration is spatially clustered and locally heterogeneous. Municipal maintenance potential was then represented through principal component analysis and classified by cluster analysis, identifying seven municipal types characterized by different combinations of depopulation, wide-area management burden, land-use conditions, and fiscal constraints. By integrating deterioration severity, LISA composition, and maintenance-potential typologies, the study distinguished municipalities where low deterioration is spatially stable, municipalities where highly deteriorated areas are locally concentrated, and municipalities where deterioration is high but spatially dispersed. These findings provide a basis for targeted support and strategic bridge management.