A Review of Bridge Abutment Scour Countermeasures

The ability to protect bridge piers and abutments from scour is critical to bridge safety. Excessive abutment scour can cause high maintenance costs or even bridge collapse resulting in the interruption of traffic and possibly death. Two approaches to scour mitigation have been taken. These are (1) bank-hardening and (2) flow-altering countermeasures. Bank-hardening methods are composed, among others, of riprap, cable-tied blocks, and geobags. Flow-altering countermeasures include spur dikes, guidebanks, parallel walls, and collars. Selection of a countermeasure involves a life-cycle cost assessment for the particular site in question as well as social and environmental issues. Three new countermeasures include parallel walls, spur dikes located locally to the abutment, and horizontal collar-type plates attached to the abutment. All three of these new countermeasures have been proven successful in the laboratory. This work will be detailed in an upcoming report as part of the NCHRP 24-18A project.