In order to consider the applicability of visual inspection to bridges maintenance, we surveyed cracks and steel bar corrosion of RC bridges near Sea of Japan in Aomori prefecture. The surveyed results were compared with the chloride ion densities near the steel bars. Through the survey, the following points have been revealed: 1) There was a case that steel bar corroded surrounding by high density chloride ion, while there was no crack on the surface of the concrete. Therefore, visual inspection did not give sufficient information about steel bars in RC bridges. 2) But in case few cracks were found on the surface of the concrete, checking increase of cracks might effective to make planning maintenance, because average intervals of cracks calculated by grid method, correlated well with chloride ion density near the steel bars. 3) Damage grades calculated from cracks conditions correlated with degree of steel bar corrosion ranked by the standard specification for concrete structures.
