ABSTRACT
The Silver Bridge over the Ohio River between West Virginia and Ohio collapsed during rush hour and it
resulted in the loss of 46 lives in 1967. This disaster caused public outcry and indicated the need for a
formalized national inspection program on the condition of the nation’s bridges. The 1968 U.S. Federal-
Aid Highway Act required the establishing of national bridge inspection standards (NBIS) for the Federal-
aid highway system. In April 1971, NBIS (FHWA, 1971) were issued for the states to inventory, inspect,
and report on the condition of the 274,000 bridges on the Federal-aid highway system. By the end of 1973,
the states had inventoried most of the bridges on the Federal-aid highway system. In 1978, the Surface
Transportation Assistance Act extended the inventory and inspection program to include bridges on
all public roads. The NBIS were revised in December 1979 to comply with the new regulation to include
a total of 577,000 bridges on all public roads in the United States. Additional revisions to the NBIS were
made in September 1988 to modify some of the bridge inspection requirements, including frequency of
routine inspection, special inspection requirements, inspector certification, and reporting requirements.
The NBIS include five provisions: inspection procedures, frequency of inspections, qualifications of
personnel, inspection reports, and inventories. The primary purpose of the NBIS is to locate, evaluate,
and act on existing bridge deficiencies to assure that the bridges are safe for the traveling public.
