New Equipment Allows Researcher to Protect Roads

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Omar Konte, a civil engineering graduate student working with Coffman, using the interferometer.

FAYETTEVILLE, Ark. – Richard Coffman, assistant professor of civil engineering, is monitoring a slope on Interstate 540 with the help of a custom-built ground-based radar interferometer. The slope, which is near Chester, Ark., is slowly moving away from the road, and while this doesn’t cause an immediate threat, Coffman’s measurements will help alert the Arkansas State Highway and Transportation Department if the movement begins to accelerate. These measurements can also be used to design a system to hold the soil in place if necessary.

Coffman’s device was built by a Swiss company called Gamma Remote Sensing, and it is one of only six in the world. Two of these six are in the United States; the other one was acquired through a National Science Foundation grant that Coffman helped prepare for the University of Missouri, where he did his graduate work.

The interferometer produces detailed images, and Coffman will compare these images over time to monitor the stability of the slope and determine what remedial measures, if any, to take. Coffman explained that the rainfall in this area causes water to build up in the soil, which can lead to slope failure.

Coffman is also measuring the movement of a slope in Malvern, Ark., that is shifting all four lanes of Interstate 30 downhill.

“This is a complex problem,” he explained. “The data that we are collecting will help to solve this problem.”

Coffman explained that he has used satellites in the past to gather this kind of information, but his new equipment can acquire an image that is 20 times more detailed than a satellite image. In addition to monitoring slopes, Coffman can use the interferometer to inspect dams and bridges for potential failures. He will also be monitoring soil expansion to study how it affects buildings, roads and other infrastructure.