In-depth inspection is one of the two most common types of bridge inspection. In contrast
with routine inspection, in-depth inspection is a close-up, hands-on inspection that generally
covers only a portion of a bridge. The Federal Highway Administration's Nondestructive
Evaluation Validation Center recently completed a study of the reliability of visual inspection
of highway bridges. Part of this study focused on the accuracy and reliability of in-depth
inspections as completed by state bridge inspectors from across the United States. Three in …

Routine inspection is the most common type of highway bridge inspection completed to
satisfy the requirements of the National Bridge Inspection Standards. Routine inspections of
highway bridges are typically completed using only visual inspection (VI) and rely heavily on
subjective assessments made by bridge inspectors. Given this practice and the fact that VI
may have limitations that affect its reliability, the Federal Highway Administration completed
a comprehensive study to examine the reliability of VI as it is currently practiced in the United …