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**Publication:****Reliability of Visual Inspection for Highway         Bridges**

**Volume I: Final Report**FHWA-RD-01-020, June 2001Chapters 1-4 (PDF - 1,381 KB) Chapter 5            -Section 5.1-5.2 (PDF         - 1,290 KB)            -Section 5.3 (PDF - 631KB)            -Section 5.4 (PDF - 2,524         KB)Chapters 6-7, References (PDF - 120 KB)       
**Volume II: Appendices**        FHWA-RD-01-021, June 2001Appendix A (PDF - 172KB)Appendices B, C, D (PDF - 518KB)Appendices E, F, G, H, I (PDF - 138KB)Appendices J, K (PDF - 3,523)Appendix L (PDF - 321KB)  

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**Learn more about Visual Inspection.****Contact:**Glenn Washer (glenn.washer@fhwa.dot.gov)
**Abstract:**        Visual Inspection is the predominant nondestructive evaluation technique         used in bridge inspections. However, since implementation of the National         Bridge Inspection Standards in 1971, a comprehensive study of the reliability         of Visual Inspection as it relates to highway bridge inspections has not         been conducted.The goals of the study include: providing overall measures         of the accuracy and reliability of Routine and In-Depth Visual Inspections,         studying the influence of several key factors that affect Routine and         In-Depth Inspections, and studying the differences between State inspection         procedures and reports. 

 Ten inspection tasks were performed at seven test bridges using State bridge         inspectors. The sample of participating inspectors included 49 inspectors         from 25 State agencies. Inspectors were provided with common information,         instruction, and tools. Inspector characteristics were measured through         self-report questionnaires, interviews, and direct measurements. 

 Routine Inspections were completed with significant variability, and the Condition         Ratings assigned varied over a range of up to five different ratings.         It is predicted that only 68 percent of the Condition Ratings will vary         within one rating point of the average, and 95 percent will vary within         two points. Factors that appeared to correlate with Routine Inspection         results include Fear of Traffic; Visual Acuity and Color Vision; Light         Intensity; Inspector Rushed Level; and perceptions of Maintenance, Complexity,         and Accessibility.

  In-Depth Inspections using Visual Inspection alone are not likely to         detect or identify the specific types of defects for which the inspection         is prescribed, and may not reveal deficiencies beyond those that could         be noted during a Routine Inspection. The overall thoroughness with which         inspectors completed one of the In-Depth tasks tended to have an impact         on the likelihood of an inspector detecting weld crack indications. Other         factors that may be related to In-Depth Inspection accuracy include: time         to complete inspection, comfort with access equipment and heights, structure         complexity and accessibility, viewing of welds, flashlight use, and number         of annual inspections performed. 

 The State procedural and reporting tasks indicated that most States follow         similar procedural and reporting criteria. Several inconsistencies were         noted with the use of the element-level inspection systems, but it is         not known if these variations are the result of State practices or inspector         use. Deck delamination surveys were found to have significant variability,         with only a few teams performing a delamination survey as part of the         Routine Inspection. 

 Learn more about Visual Inspection.

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