Corresponding Author

Heba Kassem

Subject Area

Civil and Environmental Engineering

Article Type

Original Study


Bridge failure, due to local scour at bridge circular pier foundations, has become a critical issue in river and bridge engineering, which might lead to transportation disruption, loss of lives and economic problems. Based on an experimental perspective, this study is focused on the influence of collar’s shape on decreasing scour depth at bridge piers that were explored. Hexagonal collars with three shapes were investigated (sloped, sloped with holes, and sloped with ribs). The collars were installed on the bed level with diameter equals to three times the diameter of pier. To achieve the results, experiments were performed in clear-water conditions using uniform sand for bed materials. Results indicated that all types of collars provide a considerable decrease in the scour depth and delayed the formation of scouring holes. Sloped with ribs hexagonal collar appeared to be the most effective collar shape in reducing scour around the pier by 56% reduction in the scour depth, while the upstream length, downstream length, and the width of the scour are reduced by 29%, 51%, and 19% respectively compared with the case of the pier without collars. Empirical dimensionless relations for maximum scour depth, width, and length are generated according to the experimental results.


Bridge Piers, Clear Water Scour, Countermeasures, Experimental Work, Hexagonal Collar

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.