In this study, the appearance rating method, which is now widely used to diagnose the integrity of weathering steel bridges, was reorganized based on photographs and the amount of corrosion in previous studies to clarify the classification of each category. This clearly separated the categories that should be repaired (Rating Number 1) from the others. In addition, it was also possible to determine that the rusting changes over time would not naturally shift to the rating number 1, although there is a possibility that the rusting changes from rating number 5 to rating number 2 would shift sequentially. This has enabled us to propose a more rational method for soundness diagnosis during periodic inspections.
