1998. Bridge Scour Evaluation: Screening, Analysis, and Countermeasures. 9877 1207. San Dimas, CA: U.S. Department of Agriculture, Forest Service, San Dimas Technology and Development Center. 13 p.
Scour, defined as "the erosion or removal of streambed or bank material form bridge foundations due to flowing water" is the most common cause of highway bridge failures in the United States. The Forest Service, U.S. Department of Agriculture, administers 7,650 bridges on National Forest lands, and virtually all of them are over water. Scour is also the single most common cause for bridge damage and failure on National Forest lands. To minimize future bridge flood damage and ensure public safety requires developing and implementing improved procedures for designing bridges and inspecting them for scour. Realizing this need, the Federal Highway Administration (FHWA) issued a Technical Advisory in 1988 revising the National Bridge Inspection Standards (NBIS) to require evaluation of all bridges for susceptibility to damage resulting from scour. The Forest Service is required to establish a scour evaluation program and submit reports to FHWA. In 1998, an Engineering Technology Development Proposal was funded to develop a scour evaluation program, specifically for the Forest Service, that all Regions of the Forest Service could implement. The project was to outline a single process and establish criteria, methods, and guidelines that would ensure consistency throughout the agency and eliminate duplication of effort. This document is the culmination of Phases 1 and 2 of that proposal.
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