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Visual Inspection of Highway Bridges


The Federal Highway Administration recently conducted an investigation to assess the reliability of visual inspection of highway bridges as implemented by state departments of transportation. The study focused on routine and in-depth inspection, the two most prevalent forms of visual inspection of bridges. Because visual inspection is a highly subjective nondestructive evaluation technique, the results of these bridge inspections can be highly variable and are dependent on many factors. This study included the completion of 10 bridge inspection tasks by 49 practicing state bridge inspectors. With regard to routine inspections, this study showed that condition ratings are assigned with significant variability. Specifically, approximately 68% of condition ratings are within 1 rating point of the average. The results of the in-depth superstructure inspections indicated that these inspections are not likely to detect and identify the specific types of defects for which this inspection procedure is sometimes prescribed. Specifically, widespread defects such as those normally noted during a routine inspection are likely to be noted; however, local deficiencies, such as crack indications, are unlikely to be detected. The results of the deck delamination survey indicate that the accuracy of this type of inspection is relatively poor, with few inspection teams providing results that could be considered to accurately portray the condition of the deck.

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  1. M. E. Moore, B. M. Phares, B. A. Graybeal, D. D. Rolander, and G. A.Washer, Reliability of Visual Inspection for Highway Bridges (FHWA Report Nos. FHWA-RD–01–020 and FHWA-RD–01–21, Federal Highway Administration, U.S. Department of Transportation, June 2001).

  2. Manual for Condition Evaluation of Bridges, 1994 (American Association of State Highway and Transportation Officials,Washington, D.C., 1994).

  3. Manual of Steel Construction: Load & Resistance Factor Design (American Institute of Steel Construction, United States of America, 1994).

  4. AASHTO Guide for Commonly Recognized (CoRe) Structural Elements (American Association of State Highway and Transportation Officials, Washington, D.C., 1997).

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Correspondence to Benjamin A. Graybeal.

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Graybeal, B.A., Phares, B.M., Rolander, D.D. et al. Visual Inspection of Highway Bridges. Journal of Nondestructive Evaluation 21, 67–83 (2002).

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