Riprap Design, Installation, and Maintenance at Bridges

Abstract

Many methods and criteria are available for designing riprap for erosion protection of riverbanks, bridge piers and abutments, and other highway structures in riverine environments. Different design criteria for riprap can give significantly different results for protecting the same installation. In addition, the design procedure may be confusing to apply and can result in unsuitable gradations and ambiguous specifications. In the U.S. 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. This paper provides an overview of the results of National Cooperative Highway Research Program (NCHRP) Project 24-23 which was a synthesis project to develop a comprehensive approach to riprap design, installation, and maintenance at bridges. This project provides 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 for river training countermeasures such as guide banks and spurs. The study included an evaluation of riprap failure modes and development of inspection guidelines for consideration by the Federal Highway Administration (FHWA).