Author(s): PE Clopper, PF Lagasse, JF Ruff, LW Zevenbergen (Ayres Associates, Inc Fort Collins, CO)
Publisher: Transportation Research Board
Year: 2006
Link(s): PDF  
Subjects: Riprap
NCHRP 568 cover

This report presents the findings of a study to develop design guidelines, material specifications and test methods, construction specifications, and construction, inspection, and quality control guidelines for riprap at streams and riverbanks, bridge piers and abutments, and bridge scour countermeasures. Recommendations are provided on a design equation or design approach for each application. Filter requirements, material and testing specifications, construction and installation guidelines, and inspection and quality control procedures are also recommended for each riprap application.

To guide the practitioner in developing appropriate designs for riprap armoring systems for these applications, the findings and recommendations are combined to provide design guideline appendixes for (1) Design and Specification of Rock Riprap Installations and (2) Construction, Inspection, and Maintenance of Rock Riprap Installations. This report will be particularly useful to bridge, hydraulic, and highway engineers, as well as bridge maintenance and inspection personnel responsible for design, construction, inspection, and maintenance of bridges and other highway structures.

Many different techniques are currently used to determine the size and extent of a riprap installation, and existing techniques and procedures for design of riprap protection can be confusing and difficult to apply. Depending on the technique used to size riprap, the required size of stone can vary widely. Most states have specifications for classifying riprap size and gradation, but there is not a consistent classification system or set of specifications that can be used when preparing plans or assembling a specification package for a project.

In addition, various construction practices are employed for installing riprap; many of them are not effective and projects requiring the use of riprap historically have suffered from poor construction practices and poor quality control. The intent of this study was to develop a unified set of guidelines, specifications, and procedures that can be accepted by the state DOTs.

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