Author(s): Johnny L. Morris; Jorge E. Paganortiz
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Abstract: To summarize the cuprent scour program, Technical Advisorly T 5140.20 entitled "Scour at Bridges" was issued on September 16,1988. This TA provided recommendations and guidance on how to develop and implement a scour evaluation prograrn. It was updated by Technical Advisory T 5 140.23 issued on October 28,1991. From these publications, the essential clements of a scour evaluation program follow: ●A screening process to identify bridges most likely to be vulnerable to damage from scour and thus need early attention. ●Engineering evaluations of existing bridges to establish which bridges are scour critical and the reporting of the results of these evaluations in Item 113 of the revised Bridge Recording and Coding Guide. ●A plan of action for monitoring and providing countermeasures for the scour critical bridges. In November 1988, the FHWA stressed that ".. immediate steps be taken to get the scour evaluation program underway in all the States... ". On February 5,1990, a semiannual reporting program was established to help stress the importance of implementing the scour evaluation program. On July 15,1991, the target date of January 1,1997, was established as the date by which all bridges should be evaluated which had been identified through the screening process as: (1) "low risk" that cannot be coded as4,5, 7,8, or 9 within Item 113 of the December 1988 Recording and Coding Guide; (2) "scour susceptible"; and (3) Interstate bridges with "unknown foundations" and/or over tidal waterways. On November 8,1996, the FHWA field personnel were ask to review the action plans for those bridge owners that are projected to be less than 90 percent completed with their scour evaluations by the target date. The FHWA and State highway agencies, as well as other parties, have conducted research for many years to improve the estimating procedures for determining scour at bridges. Even so, the best available current technology represented by HEC- I 8 needs improvement. Ongoing and proposed research within the highway hydraulic community addresses scour needs and will result in improved methodology.
Year: 1997