Synthesis of Unmanned Aerial Vehicle Applications for Infrastructures

This paper is intended to provide the state-of-the-art and of-the-practice on visual inspection, monitoring, and analysis of infrastructure using unmanned aerial vehicles (UAVs). Several researchers have inspected various civil infrastructures, including bridges, buildings, and other structures, by capturing close-up images or recording videos, while operating UAVs. Various image analysis tools, such as the algorithm Morphological Link for Crack (Morpholink-C), were able to conduct precise measurements of crack thickness and length. Corrosion has also been detected using texture and color algorithms to investigate UAV-based images. Other analysis methods include structurally integrated sensors, such as digital image correlation equipment, which have helped to capture structural behaviors using UAVs. After the literature review was completed, a nationwide survey was distributed to Departments of Transportation (DOTs) to evaluate the current UAV-enabled inspection techniques that different DOTs have used or are planning to use for visual damage assessment for critical transportation infrastructures, especially bridges. Furthermore, a pertinent UAV selection was completed to indicate suitable UAVs for bridge inspection. Primary findings have shown that UAV-enabled infrastructure inspection techniques have been successfully developed to detect a broad variety of damage (including cracks and corrosions), and a few DOTs have used UAVs to inspect bridges as a more economical and versatile tool.