| Popis: |
For years bridge designers in the U.S. have used FHWA Publication Hydraulic Engineering Circular No. 18 (HEC 18) as a principal tool to determine scour depths. Increasingly, though, practitioners recognize that some of the circular's standard equations over predict scour depth for certain geologic and hydraulic conditions. In an effort to improve scour design and evaluation methods, the New Jersey Department of Transportation (NJDOT) recently conducted a survey of current scour practice of DOTs across the U.S. The ten-question survey queried agencies about their design standards, experiences with failures, monitoring programs, and countermeasure preferences, among other things. This paper presents the results of the nationwide scour survey. Highlighted are the creative and diverse approaches by some states to either modify HEC 18 procedures or develop alternative scour prediction methods. The paper also discusses critical geologic, hydraulic, and hydrologic parameters for rational evaluation of scour depth, gleaned from both the survey and local experience with New Jersey bridges. |
