The National Academies

NCHRP 24-07 [Completed]

Countermeasures to Protect Bridge Piers from Scour

  Project Data
Funds: $400,000
Research Agency: University of Minnesota
Principal Investigator: Gary Parker and Rick Voigt
Effective Date: 5/1/1995
Completion Date: 10/31/1998

Scour at bridges is a potential safety hazard to the traveling public. Recognizing this, the Federal Highway Administration has mandated the evaluation of all highway bridges for scour vulnerability by 1997. Accordingly, a nationwide effort by state and federal agencies is underway to evaluate actual and predicted scour depths.

Bridge pier scour is a major concern; it is a dynamic phenomenon that varies with water depth and angle of flow, pier shape and width, and other factors. If scour at a pier can affect the stability of a bridge, countermeasures to protect the pier should be considered. Because of the critical role of countermeasures in ensuring bridge integrity, as well as their potential high cost, it is important that they be selected, designed, and constructed based on site conditions and other factors. It is also important to evaluate the performance of countermeasures on a continuing basis. Comprehensive, practical guidance on the use of scour countermeasures for pier protection is lacking, and research is needed to provide this information.

The objective of this research is to develop comprehensive, practical guidance on the applicability, design, construction, maintenance, performance evaluation, and costs of scour countermeasures for bridge pier protection.

The research includes the following tasks: (1) Review relevant practice, performance data, research findings, and other information from both foreign and domestic sources to identify existing and potential countermeasures. Identify selection and performance evaluation practices for countermeasures, design procedures and guidelines, and construction and maintenance guidelines. Submit the list of identified countermeasures for NCHRP review. The information under this task shall be assembled from both technical literature and unpublished experiences of engineers, bridge owners, and others. (2) Develop an approach for screening each of the countermeasures from Task 1 with respect to the overall project objective. The approach shall include criteria on which to judge the countermeasures, and a conceptual framework for assessing how well each countermeasure meets the criteria. The criteria for screening the countermeasures should include, but not be limited to, effectiveness, constructibility, reliability, maintainability, and cost. Document and submit the approach for NCHRP review. (3) Conduct a preliminary screening of the countermeasures using the approach developed in Task 2. Submit an interim report that documents the research of Tasks 1, 2, and 3, including the results of the screenings. The report also must include a list of promising countermeasures recommended for further study under this project. (4) For each of the countermeasures recommended in Task 3 for further study, develop a work plan for the preparation of the following: (a) guidelines on the applicability (i.e., warrants for use or selection criteria), (b) design procedures and guidelines, (c) construction and maintenance guidelines, (d) performance evaluation guidelines (including effectiveness and reliability), and (e) initial and long-term cost information. It is expected that the work plan for each countermeasure may vary, depending on the amount and criticality of gaps in the available information. It is anticipated that sufficient information exists to move directly to the development of items (a) through (e) for some of the countermeasures, while for others it may be necessary to conduct field investigations or laboratory or other studies to provide additional information. Each work plan must include a detailed discussion of anticipated tasks, as well as an itemized budget. Develop a recommended format for presenting the results of items (a) through (e). (5) Submit the set of work plans from Task 4 in an interim report. The report also must include the recommended format for presenting the results of items (a) through (e) (Task 4). NCHRP review and approval of the interim report will be required before proceeding with work on the remaining tasks. The contractor should anticipate meeting with the project panel to discuss the proposed research plans. (6) Execute the work plans approved in Task 5 to develop items (a) through (e) of Task 4. (7) Submit a final report documenting the entire research effort. The guidelines on applicability (i.e., warrants for use or selection criteria), design procedures and guidelines, construction and maintenance guidelines, performance evaluation guidelines, and cost information shall be provided in an appendix to the report and must be in a format suitable for use by practicing engineers.

Status: This research has been completed. The principal investigators submitted the revised final report in December 1998. The research results for this project and NCHRP Project 24-7(2) were published together as NCHRP Report 593.

Product Availability: The December 1998 unedited final report for NCHRP Project 24-07 as prepared by the University of Minnesota is available as Volume 1-User's Guide and Volume 2-Final Report.

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