Monitoring Critical Infrastructure with Unmanned Aerial Vehicles

OverviewA large number critical infrastructure components in the United States, including bridges, [1] pipelines [2] and dams [3] were built more than 50 years ago. [4] Due to aging and deterioration, the reliability and perfor-mance of these components continue to decrease. [5] Further damage or disruption of services caused by aging infrastructure would negatively affect national security, as well as military and civilian components that rely on critical infrastructure for daily operations. [6] Using unmanned ae-rial vehicles, or UAVs, equipped with thermal imaging payloads provides an emerging solution to monitor the wide range of aging infrastructure in the United States. Thermographic cameras capture the difference in heat between objects and enable the detection of variances in surface temperatures. [7] Among these differences in surface temperatures are age-related failures, such as excessive friction, stress cracks and gas, making thermographic monitoring possible. [7,8,9] Use cases of infrared thermography for critical infrastructure monitoring include dam crack de-tection, electrical grid monitoring and pipeline leak detection.

Dam Crack DetectionMore than half of the nearly 700 dams operated and overseen by the U.S. Army Corps of Engineers meet or exceed their intended 50-year service life span. [3] Aging dams are susceptible to developing cracks or leaks in their structure, which could lead to dam failure. [10] Other stress factors, such as seismic activity, compound the natural aging process and cause damage. [11] Should a dam fail, the amount of water released would cause catastrophic damage, as well as potential injury and death to those downstream. Cracks in dams appear in thermal images taken by UAVs due to the difference in heat between the void and the sur-rounding concrete structure. [12] In instances of leaks, under thermal im-aging, the evaporative cooling effect of water would make these cracks appear cooler than the surrounding area, thus showing up as a shade of blue, denoting a loss of heat. [13,14] Thermal imaging from UAVs allows analysts to see damage close to the face of the dam, allowing for the detection of small cracks that would otherwise be unnoticeable from a distance, allowing dam repair before further damage. Since detected damage suggests imminent failure of the dam, evacuation can begin for those downstream.

Electrical Grid MonitoringThe American electric grid’s distribution components average 40 years old and shows signs of aging. [15] Failure of electrical components due to aging may eventually lead to a blackout, cutting power to civilian and

military installations. [16,18] Electrical components deteriorate over time due to vibration, fatigue and corrosion, showing an increase in tem-perature before breaking down. [16,17] Electrical resistance of loose and corroded electrical connections is higher than properly performing connections. [17] This higher electrical resistance causes an increase in temperature at the connection. [17] Due to the increase in heat, ther-mography can detect early signs of failure in electrical distribution sys-tems. [16] Thermal imaging also effectively detects the overheating of substation components, such as transformers, caused by fluid leaks or the degradation of internal insulation. UAVs allow analysts to hover above infrastructure and collect thermal data from angles unavailable to personnel on the ground level. [16] Detecting components near failure allows for proactive maintenance and replacement, which reduces grid downtime.

Pipeline Leak DetectionThe majority of pipelines within the United States were built between 1950s and 1960s. Some pipelines built before 1940, however, remain in use. [2] Damage caused by pipeline aging contributed to 15 percent of incidents reported to the Pipeline Hazardous Materials Safety Ad-ministration from 2002 to 2009, including those caused by corrosion and body, joint and weld failures. [19] Damaged, weakened and leaking pipelines threaten surrounding populations, wildlife and local water sup-plies. These pipelines also present a fire or explosion risk. [20] Leaks in compressed gas pipelines will display as cooler than the surrounded area due to the change in pressure. [21] Crude oil brine and other liquids transported through pipelines typically remain at a higher temperature than the surrounding area, making liquid leaks display a temperature in-crease on the pipeline. [21] Even if the leak and the surrounding pipeline display a low variance in temperatures, the movement of gas compared to their static surroundings shows up under thermography. [22] UAVs allow analysts to survey the length of a pipeline while remaining in a fixed location, reducing their risk to leaks and fires. As the unaided eye cannot detect many pipeline leaks, [23] thermal imaging enables early detection, allowing repairs to begin more rapidly while mitigating nega-tive environmental impact and fire risks.

SummaryIn response to America’s aging infrastructure, the Department of De-fense and the Department of Homeland Security could leverage UAVs equipped with thermal imaging payloads to monitor and protect aging infrastructure stretching over a vast area. With proactive monitoring, personnel may discover issues such as leaks and cracks, which threaten the functionality of critical infrastructure. The continued decrease in sen-sor size and weight will enable wider integration with UAV technology.

Unmanned aerial vehicles can detect signs of aging and deterioration in critical infrastructure with thermographic cameras. (Image courtesy of Adobe Stock)

hdiac.org • 12/14/2016

By: Timothy Ruppert ● HDIAC Analyst

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hdiac.org • 12/14/2016

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