A recent national bridge inventory indicated an alarming number of this country's bridges classified as either structurally deficient or functionally obsolete. To compound the problem, Federally required inspections, which are usually performed visually, often fail to detect cracks or other hidden defects that would affect the structural reliability of bridges.

For more than 20 years, FHWA has encouraged and sponsored research and development of instrumentation to provide State highway agencies with better tools for the nondestructive evaluation (NDE) of bridges. Bridge inspection technology development has become an evolving process as new systems and procedures continually emerge. These rapid advances have caused a backlog of sophisticated instrumentation and equipment in need of further development and testing. In most cases, the technology may remain on the shelf or is rarely used because there are no practical, cost-effective applications on which testing can be performed, or because of a lack of proven test procedures or field experience by test personnel.

This project will further the use of innovative NDE technology by demonstrating and testing equipment and instrumentation to the States. Systems now being considered are AE, magnetic field disturbance (MFD), impact echo, and magnetic perturbation of cables (MPC). Others will be added for testing and evaluation as this evolving technology matures.

Development of a demonstration project on NDE for highway structures has been deferred to 1999 in order to collect more data on promising technology. A contract for an "Impact Echo System for NDE of PostTensioned Concrete Bridge Structures" was successfully completed on mid1994. Additional studies are subject to available funding. States may request to participate in this project to evaluate promising, innovative bridge inspection techniques.

Drafts of the Guidelines for applying AE technology to bridge inspections have been completed. Guidelines to applying AE technology for in-process weld monitoring have been developed as well.

Three videotapes on AE testing have been prepared. Field Trials of the Acoustic Emission Weld Monitor (FHWA-TS-88-021) and Evaluation of Steel in Concrete Bridges: The MFD System (FHWA-SA-91-026) are available from the Research and Development Report Center, HRD-11, 6300 Georgetown Pike, McLean, Virginia 22101-2296.

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HIGHWAYTECHNET   VIRTUAL EXPO   STRUCTURES INDEX

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U.S. Department of Transportation
Federal Highway Administration