Many methods and criteria are available for designing riprap for erosion protection of riverbanks, bridge piers and abutments, guidebanks, and other highway structures in riverine environments. Different design criteria for riprap can give different results for protecting the same installation. A design procedure may be confusing to apply and can result in unsuitable gradations and ambiguous specifications. Many state highway departments have developed their own specifications based on trial, error, and field experience. To provide adequate protection, riprap must be properly designed and specified. Equally important, the rock material must be produced and installed to satisfy the specifications requirements and the design intent. The objectives for NCHRP Project 24-23 were to develop a comprehensive approach to riprap design, installation, and maintenance at bridges. As a preview to the project, preliminary results of a sensitivity analysis of selected revetment riprap design equations are presented. When completed, NCHRP 24-23 will provide design guidelines, material specifications and test methods, construction specifications and construction inspection and quality control guidelines for riprap for bankline revetment, bridge pier and abutment protection, and river training countermeasures, such as guidebanks and spurs.
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