The National Bridge Inspection Standards (NBIS) were originally created in 1971 and were subsequently updated in 1988 and 2004 (effective 2005). The Code of Federal Regulations (23CFR151 and 23CFR650) outlines the national bridge inspection program. The Federal Highway Administration (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 hisprogram under the federal regulations, a variety of local policies, procedures, and techniques are currently employed across the United States thatall comply with the NBIS. This paper provides an overview of nationwide activities and compares the underwater inspection techniques and methods used by various states. All underwater inspection techniques and methods are described in detail with the associated advantages and limitations of each discussed. This paper also discusses various state-specific policies onunderwater inspector qualifications, underwater inspection intervals, data gathering techniques, inspection report content, and state policies for non-NBIS covered structures less than 20 feet long. Historic data on trends for managing underwater inspection programs are reviewed, and future anticipated trends are discussed. Although railway bridges, ferry terminals,and ports, and harbors facilities are not discussed herein, many of the underwater inspection techniques and methods are also frequently used on those transportation structures by their maintaining agencies. Therefore, the paper will be informative to all program managers dealing with underwater inspection work.
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