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New Mexico State University

New Mexico State University

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New Mexico State professor uses virtual reality to aid bridge inspections

Using computers equipped with virtual reality programs, three-dimensional map making capabilities and ultrasonic testing, three New Mexico State University professors hope to revolutionize the art and science of bridge inspection.

Kenneth White, left, professor and department head of New Mexico State's civil and geological engineering department; David Jauregui, center, CGE assistant professor, and Clinton Woodward, CGE professor, stand with a camera used in photogrammetry, one of

David Jauregui, an assistant professor of civil and geological engineering (CGE), Kenneth White, CGE department head, and Clinton Woodward, a CGE professor, believe the high-tech methods are the future of bridge inspection, Jauregui said.

Funded by a $600,000 grant from the New Mexico State Highway and Transportation Department and the Federal Highway Administration, they hope to demonstrate the methods' effectiveness by carrying out long-term monitoring of the culverts and bridges on Highway 44, a stretch of state highway between San Ysidro and Bloomfield in northwestern New Mexico.

"A bridge inspection report is traditionally a written document which includes some fairly general descriptions, like 'Concrete spalling and exposed rebar noted on bearing seat of abutment No. 1.' Pictures give much greater clarity," Jauregui said.

"What we'd like to see is the inspection report replaced by a CD-Rom disc containing photos in a digital, virtual reality-based format, supplemented by the written material. It would more thoroughly describe the observed bridge condition and also would be less tedious to prepare and review for the bridge inspector," he said.

In his campus office, Jauregui demonstrated how a virtual reality program gives the sense of standing under a bridge observing its physical condition. He brought a photograph of a highway bridge up on his computer screen. Then, with a click of his mouse, he switched the direction from which the bridge was shown on the screen. With another click, the screen zoomed in on a two-foot-square section of the bridge to show a longitudinal crack running the length of an abutment that engineers call "delamination."

"Traditional bridge inspection reports have a scale of 0 to 9 to rate a bridge's condition; however, using those scales can be highly subjective. Recent studies have shown the ratings can vary as much as two points between inspectors. Using a virtual reality program, we hope to improve the current methods to achieve better agreement from inspector to inspector," he said.

Using such a program, bridge inspectors would take a large number of photographs at the inspection site, then "stitch" them together into a continuous, panoramic, presentation. The program allows a user to arrange the pictures, then supplement them with text, maps, design drawings, oral histories and Internet links, Jauregui said.

To monitor the bridges on Highway 44, the three professors also plan to use close-range photogrammetry software, which allows users to make three-dimensional measurements from photographs taken from as close as four inches to as far away as 330 feet. Using ultrasound, they will test the integrity of materials in the bridges by sending sound waves through them and measuring the reduction in the sound waves' strength.

Highway 44 is being expanded from a two-lane to a four-lane roadway, with new bridges being built to replace old ones. The work is scheduled to be completed in 2002. In what is a first for New Mexico, the state highway department has obtained a warranty from the contractor for the work and materials. This unusual type of financing is one reason the state and federal agencies are willing to take extra steps to monitor the bridges, Jauregui explained.

The three professors may also team with the state and federal agencies to do a similar long-term monitoring project for the "Big I" -- the Interstate 25 and Interstate 40 interchange in Albuquerque -- once that reconstruction project is completed sometime in 2002. Grant funding for that project is pending, he added.

Photo is available at http://kiernan.nmsu.edu/newsphoto/White.jpg.
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