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Collapse of the Silver Bridge over Ohio river between West Virginia and Ohio in 1967, which killed over 40 people, highlighted the need of conducting frequent safety inspections. Consequently, the Federal-Aid Highway Act of 1968 was passed that required the U.S. Secretary of Transportation to establish the National Bridge Inspection Standards (NBIS) to ensure the safety of the traveling public. The Act directed the States to maintain an inventory of bridges in the Federal-aid highway system. This Act was amended several times and the Federal Highway Administration (FHWA) revised its regulations to develop the current version of the Standards. The National Bridge Inspection Standards provide guidelines on the types of bridges that are required to be inspected, inspection frequency, qualification of bridge inspectors, and documenting observations and maintenance of bridge inventories. As per the Standards, bridge components are classified into three major groups: bridge deck, superstructure, and substructure. A rating between 0 and 9 is assigned to these three components based on their condition at the time of inspection. Due to several drawbacks associated with the NBIS rating procedures, in early 1990s, element level bridge inspection method was introduced. The AASHTO Manual for Bridge Element Inspection provides the procedures and guidelines for element level inspection. This manual provides two element classifications: National Bridge Elements (NBEs) and Bridge Management Elements (BMEs). Also, highway agencies can define and incorporate additional elements into their databases as Agency-Developed Elements (ADEs). Four levels of condition states are defined with guidance statements for inspectors. This article describes the evolution of bridge inspection procedures, challenges for effective use of data, and the required changes to address specific conditions for improving inspection data accuracy, quality, and usefulness. |
