Overview and Comparison of Nationwide Underwater Bridge Inspection Practices

The National Bridge Inspection Standards (NBIS) were originally created in 1971 and subsequently updated in 1988 and 2004 (effective 2005). The U.S. Code (23USC151) and the Code of Federal Regulations (23CFR650 Subpart C) outline the national bridge inspection program. FHWA requires that all highway bridges with a submerged substructure be inspected underwater to assess the structural integrity with certainty. Since each state program manager has the responsibility and authority to manage his or her own program under the federal regulations, a variety of local policies, procedures, and techniques are currently employed across the United States, which all comply with the NBIS. An overview is provided of nationwide activities, and underwater inspection techniques and methods used by various states are compared. All underwater inspection techniques and methods are described in detail, with the associated advantages and limitations of each discussed. Also discussed are various state-specific policies on underwater inspector qualifications, underwater inspection intervals, data-gathering techniques, inspection report content, and state policies for non–NBIS-covered structures less than 20 ft long. Historical data on trends for managing underwater inspection programs are reviewed, and future anticipated trends are discussed. Although railway bridges, ferry terminals, and port facilities are not discussed, many underwater inspection techniques and methods are also frequently used on those transportation structures by their maintaining agencies. Data would be informative to all program managers dealing with underwater inspection work.