Damage Control

The old saying “A picture is worth a thousand words” took on added meaning recently when Jie Gong, an assistant professor in the Department of Civil and Environmental Engineering at the School of Engineering, and four of his students traveled to parts of Texas ravaged by Hurricane Harvey. The devastating hurricane led to at least 82 deaths, caused almost $200 billion in damage, dumped more than 40 inches of rain, displaced more than 30,000 people, and required 13,000 rescue efforts.

Over the course of just three days, the Rutgers team took an astounding 60,000 pictures—only these were no ordinary pictures. They were highly detailed images that Gong and his students captured while driving around in a state-of-the-art vehicle rigged with sophisticated imaging equipment. In the storm’s aftermath, they could offer important insights into how and which structures were punished and what might be done to minimize a similar calamity. Their research could have an impact on the adaptation of more robust building codes for residential areas, where houses, as opposed to reinforced city buildings, could be buttressed by using more appropriate building materials or construction methods, or both.

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Jie Gong, center, was accompanied by four graduate students to evaluate the damage wrought by Hurricane Harvey in two coastal residential communities in Texas. Using a specially equipped van, featuring roof-mounted scanners and sensors that took thousands of three-dimensional scans and panoramic photographs in just three days, the team documented the scope and variety of wreckage caused by wind and rain.

Photography: 

courtesy Jie Gong

“Given the Category 4 wind force and the multihazard nature of the storm, certain levels of damage to home properties are bound to happen. We were interested in the variability in wind and storm surge damage to homes that seem to have little difference from each other,” says Gong, who traveled to Rockport and Port Aransas, two coastal communities southwest of Houston, just days after the hurricane landed on August 25. The Rutgers team was dispatched as part of the National Science Foundation’s Geotechnical Extreme Events Reconnaissance Association, which sponsors research in areas hit by natural disasters in order to assess the impact on infrastructure. Gong and his students were assisted by students from Princeton University and the University of Texas at Austin.

“We were not conducting traditional property-to-property inspections,” Gong says. The students spent three days driving from New Jersey to Texas  in the mobile LiDAR system vehicle, which is equipped with a three-dimensional imaging system. The van, owned and outfitted by Rutgers, features roof-mounted scanners and sensors that take panoramic photos and three-dimensional scans. Roughly 15,000 properties in the two towns were photographed and scanned. “It’s a virtual reality of damaged sites,” Gong says. “We look to see what building materials are more vulnerable to wind speed. And not just building materials, but also architectural forms.”

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This three-dimensional image of a community in Rockport, Texas, was generated by a laser scanner mounted on the data collection van used by Jie Gong, an assistant professor in the School of Engineering, and his team of graduate students who last August surveyed the damage wrought by Hurricane Harvey in Texas. The colors represent elevations. Some houses were severely damaged while others were largely unaffected—differences that can be attributed to variables such as the height of homes, building materials, and construction methods.

Photography: 

courtesy Jie Gong

Each property gets a detailed assessment of its roof configuration, walls, and framing. “We map it out, taking precise measurements of the buildings’ elevations,” he says. “It may provide us with some insights into building practices, and whether buildings like these can sustain the stress of future weather systems.”

In many cases, similar-looking homes on the same block had wildly different degrees of damage—some destroyed, some barely scathed. Although not yet conclusive at this point in the analysis, buildings that had been elevated on stilts to avoid flooding, much the way homes at the New Jersey shore were raised post Hurricane Sandy, seemed to receive the worst of the wind damage because of their exposure. The shape of the roof also had a bearing on the severity of damage. Steeply pitched roofs, although providing more interior room and efficient in shedding snow or rain, are particularly vulnerable to wind, Gong points out.

“With our mobile scanning system, we could very quickly and accurately measure the relationship between elevation and damage,” says Yi Yu, a third-year civil engineering graduate student who was a member of the Rutgers team. “So now, maybe homeowners, in rebuilding their homes, can take some new precautions.”

Nenad Gucunski, chair of the Department of Civil and Environmental Engineering, says that the students’ hands-on experience is invaluable, as was the case when another group of students assessed damage following Hurricane Sandy. “This is what we are trying to do in many other areas,” he says, “by having the students get out into the field and start seeing things so that they can start asking the right questions.”

The result was a very accurate documentation of the damage. The photographs are more than images; they are images of structures with their dimensions perfectly captured. “It’s not just imaging,” says Gucunski, “but quantitative information we can use to better prepare for events by not repeating mistakes of the past.”