To determine the current performance of inspectors with the industry's present standards of training, a comprehensive Probability of Detection (POD) study is underway to determine the likelihood of inspectors finding cracks, surface corrosion and weld defects of various sizes on a bridge structure. This study will test multiple inspectors’ abilities to identify different defects under various environmental conditions on a bridge structure. The study will provide state transportation agencies, as well as private inspection agencies, invaluable information regarding typical inspector performance. The outcomes will be used to establish procedures to improve inspection reliability, and develop inspector performance-based certification criteria and procedures.