FHWA NDE CENTER RESEARCH & DEVELOPMENT
Visual Inspection Study Update
The most recent work on the Visual Inspection study has been centered around
finalizing the data analysis and preparation of a final report. The final report is approximately 800 pages in length and focuses on
the accuracy and reliability of the two most common types of bridge inspections completed to satisfy the National Bridge Inspection
Program requirements: Routine and In-depth.
The experimental program for this study consisted of having a representative sample of practicing bridge inspectors complete
a series of 10 pre-defined inspection scenarios at the Federal Highway Administration (FHWA) Nondestructive Evaluation (NDE) Center test bridges under realistic summer conditions. Quantifiable
information regarding the inspection environment was collected to establish the influence on reliability. Additionally, extensive information
was collected about the inspector's physical and psychological characteristics, allowing the influence of these characteristics on
VI reliability to be assessed. Seven of the FHWA NDE Center test bridges were utilized to conduct the field inspections and the
FHWA NDE Center laboratory for controlled measurements.
A number of important conclusions were developed from the experimental study and are summarized in the final report. As an
example, it was found that Routine Inspections are completed with significant variability. This variability is found in all aspects of the
inspection process but is most prominent in the assignment of Condition Ratings, where bridge owners can expect 95% of
Condition Ratings to be spread over five rating points. With respect to In-depth Inspection, it appears unlikely that In-depth
Inspections will correctly detect and identify the types of defects for which those types of inspections are typically prescribed. Further,
a significant proportion of In-depth Inspections will not reveal deficiencies beyond those that could be noted during a Routine Inspection.
Future work related to the Visual Inspection study will include two primary tasks. First, a review of the work by an Industry Expert
Panel (IEP) is currently on-going and will be culminated in a group meeting on September 19 and 20, 2000. The IEP is a multi-discipline
group consisting of experts in the areas of Nondestructive Testing and bridge engineering that was developed to provide technical
assistance to the study team. Following the IEP meeting, the report will be finalized and FHWA NDE Center will start the formal publication process.
It is anticipated that the final report will be published by the end of 2000.
For more information, please contact either by e-mail or telephone.
Frank Jalinoos (202) 493-3082
frank.jalinoos@fhwa.dot.gov
Preceding Work on the Visual Inspection Study
