Potential of roughening geometric elements as bridge pier local scour countermeasures

The safety of bridges can be endangered by sediment erosion occurring around bridge piers. To mitigate this issue, this study examined the use of different roughening geometric elements (RGEs) on the upstream surface of bridge piers. Keeping the clear-water conditions, laboratory experiments were conducted using five RGEs and their one-to-one ten combinations, along with two square pier dimensions, and three separate flow water depths. To evaluate the performance of the RGE piers, a case of an unprotected pier was also tested. Although the use of RGEs caused an elongated scour pit length of up to 8% upstream of the bridge piers, they proved to be successful in decreasing the maximum scour depth (35%), upstream gradient of scour pit (38%), scour pit surface area (16.34%), and volume of the scour pit (27.34%) upstream of the pier when compared to piers without protection.