An inspector’s ability to correctly identify surface and internal defects in steel bridge components is critical to protecting public safety. Ensuring that inspectors are properly trained and adequately equipped to detect these defects in locations that are difficult to access and/or in unfavorable environmental conditions must be a high priority. While the Federal Highway Administration and individual state departments of transportation have guidelines for inspector qualifications, trainings, and certifications, there is very little emphasis placed on evaluating or “testing: a given inspector’s capability to characterize defects in the field. As a result, there is also very little, if any, data on how well a given inspector actually performs or the variability which can be expected between inspectors.

This comprehensive Probability of Detection (POD) study was conducted to establish the ability of an inspector with the current required training to locate and quantify cracks in steel bridge components. This study is believed to be the first statistically-significant study of its kind in the United States.

Report Number



bridge inspection, fatigue cracking, probability of detection

SPR Number


Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, IN

Date of this Version