A Comparative Review of Local Scour Protection Methods for Bridge Foundations

Abstract

Local scour around bridge foundations remains one of the principal causes of structural failure in hydraulic infrastructure worldwide. The progressive removal of bed sediments around piers and abutments under high-flow conditions can destabilise foundations and, ultimately, cause catastrophic bridge collapse. A wide array of countermeasures has been developed and deployed over several decades, ranging from conventional riprap and granular armour systems to innovative geosynthetic technologies, collar installations, flow-altering devices, and hybrid combinations thereof. This review systematically compares these protection methods on the basis of their hydraulic effectiveness, design complexity, construction feasibility, long-term durability, and economic considerations. Primary literature published between 2005 and 2026, complemented by seminal classic studies, was synthesised to evaluate the current state of knowledge and identify research gaps. The findings indicate that, whilst riprap remains the most widely adopted countermeasure due to its relative simplicity and the availability of established design guidance, collar-based and flow-altering devices demonstrate superior hydraulic efficiency under certain conditions. Geosynthetic and grouted systems offer improved durability in aggressive hydraulic environments, although their installation complexity may limit applicability at remote or subaqueous sites. Hybrid approaches combining multiple methods exhibit the greatest overall performance but are constrained by higher costs and design uncertainty. This review identifies key directions for future research, including enhanced monitoring protocols, standardised performance benchmarking, and the integration of real-time structural health monitoring with scour protection systems.