ABSTRACT
In the Japanese railway network, unstable bridge piers due to river scouring can lead to disaster and thus their maintenance is a major challenge. To prevent scouring disasters at river bridges, it is essential to check the state of the bridge piers by conducting visual inspections at regular intervals. If a bridge pier is judged by visual inspection to be unstable, a detailed inspection is performed and the need for countermeasures against the risk of scouring is examined.
During the visual inspection it is important to identify bridge piers that are susceptible to scouring. Several approaches have been proposed for the identification method, and their application generally requires detailed inspections and expertise in river engineering. However, it is not realistic to use an inspection method that requires special expertise, because the railway engineers are responsible for the general maintenance, but not always have special expertise in river engineering.
Therefore, in Japanese railways, high-risk bridge piers are efficiently identified by visual inspection by applying a management method based on a score table. As an attention point, this score table is specifically for identifying bridge piers with a high risk of scouring disaster in the future; it does not evaluate the overall soundness of the bridge piers.
This method uses the environmental conditions of the river, structural conditions of the bridge piers and protection conditions of the bridge piers as evaluation items generally considered as factors affecting the river scouring of bridge piers, and scores are assigned to each item (Table 1).
In this method, the total sum of the points for the respective evaluation items were calculated in units of bridge pier, and bridge piers with a lower total sum of the points were judged to have a higher risk of scouring disaster in the future. The validity of this method is confirmed based on the fact that the evaluation results obtained by this method agree with expert’s judgement.
