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An Unmanned Aircraft System (UAS) is defined by the Federal Aviation Administration (FAA) as an aircraft operated without the possibility of direct human intervention from within the aircraft. Unmanned aircraft are familiarly referred to as drones; and the names can be used interchangeably. The UAS is controlled either autonomously or with the use of a remote control by a pilot from the ground. These UASs offer a wide range of imaging technologies which include photographic stills; video; and infrared sensors that can be viewed live and later processed to assist with inspections. Bridge inspections often pose logistical challenges to efficiently and effectively inspect a wide variety of structure types; therefore; inspection by UAS is a solution that can be safe and cost-effective. The Minnesota Department of Transportation (MnDOT) and Collins Engineers have been researching the use of UASs as a tool for bridge inspections in a multi-phase project. This phase of the study research identified potential applications of UAS technology to aid in bridge inspections and is a continuation of a previous study by the MnDOT.

The increasing costs of bridge inspections are a concern for the Minnesota Department of Transportation (MnDOT). The use of Unmanned Aerial Vehicles (UAV) may help alleviate these costs and improve the quality of bridge inspections. The overall goal of the UAV Bridge Inspection Demonstration Project was to study the effectiveness of utilizing UAV technology as it could apply to bridge safety inspections. The project team investigated the technology on four bridges located throughout Minnesota. The project team evaluated the UAVs effectiveness as it could apply to bridge inspections based on UAV field results. Various UAV capabilities were utilized to evaluate current technologies as they relate to use in bridge inspections. This study details the advantages and challenges of potentially using UAVs to aid in bridge inspection, an analysis of current and future UAV technologies as they relate to bridge inspection, and an analysis describing how current and future technologies adhere to the National Bridge Inspection Standards.

Steel corrosion on bridges and ancillary structures due to environmental effects and deicing chemicals is a serious problem for Minnesota's infrastructure. The ability to detect; locate; and measure corrosion is an important aspect of structure inspection. Accurate thickness measurements and corrosion mapping are essential for determining load capacity of structural members on bridges and ancillary structures. The Minnesota Department of Transportation purchased an OmniScan Phased Array Corrosion Mapping System. Unlike conventional ultrasonic equipment; this system provides detailed three-dimensional images of structural members including the remaining section of members that exhibit corrosion. This gives engineers better tools to visualize and evaluate the condition of bridges than was previously possible. With the future purchase of additional transducers; the OmniScan can also be used for enhanced inspection of welds and bridge pins.

The hydraulics unit in MnDOT's bridge office applied for a research grant to develop in-house underwater acoustic 3D imaging capabilities. This research report presents both stationary and mobile scanning techniques; outlines the setup of both systems; discusses field operations; summarizes the data analysis and post-processing of images; and reviews lessons learned. Several case studies will frame a discussion of the capabilities and limitations of 3D acoustic imaging for underwater bridge inspection. The case studies provide examples of different applications of this technology. Underwater acoustic imaging has been shown to have real value to bridge inspectors and owners for a variety of applications.

MnDOT has identified the need to develop a methodology to quantify when a steel bridge system is considered fracture critical based on Federal Highway Administration recommendations. The overall goal of this project was to research existing applicable fracture critical research papers and publications, develop a methodology for determining whether a bridge is fracture critical or not based on this research, then apply this methodology to six different fracture critical steel pier caps as a refined analysis. This refined analysis used advanced computer modeling software to develop a 3-D model of the bridge, and then simulated localized failure modes at the fracture critical steel pier caps. These simulated failures were used to determine the adequacy of load path redundancy to the remaining portion of the bridge and whether a catastrophic failure of the entire bridge would occur.

Drones for bridge inspection research has been completed by MnDOT in multiple phases since 2015. As of summer, 2017, Phase III of this research began using the SenseFly Albris and the Flyability Elios, a collision-tolerant drone more suited to confined spaces such as box girders, culverts, or areas that are difficult to access. Due to the success of this research, MnDOT Metro District purchased the Elios drone to supplement bridge inspection access where space is confined and optimal lane closures are prohibited, which has been an on-going issue in the District due to traffic volumes. This project implements drone inspection for the metro bridge inventory and other similar representative structures by creating an inspection plan that identifies bridges best suited for drone use, what parameters govern drone use in bridge inspection, and how unmanned aircraft systems (UAS) can be integrated into standard inspection operations. The project explores relevant technology, including reality modeling software, drone hardware, artificial intelligence, and autonomous flights. This project also delivers the UAS Safety and Operation Manual specific to the Metro District.

The Building Services Section (BSS) owns and operates 888 individual buildings at 269 sites throughout Minnesota. BSS is exploring ways collect, process and communicate as-built data for their sites and buildings with imaging and scanning technology. This Transportation Research Synthesis documents the state of the industry and identifies previous research and implementation regarding 360-degree point cloud and reality modeling technology for building management.

Bridges are a key part of our transportation system and maintaining this infrastructure is important to ensure the safety of the traveling public and to effectively manage these valuable assets. Safety inspections not only ensure the structural integrity of a bridge but provide valuable data to decision makers. The Minnesota Department of Transportation and Collins Engineers; Inc. has completed this third phase of research focused on utilizing drones as a tool for improving the quality of bridge inspections. The previous phases focused on the rules and regulations; drone hardware and the ability of drones to collect quality inspection data. This phase of research has identified new drone technology and methods to address limitations identified in Phase II. More importantly; this research phase has focused on the value of data collected during the inspection and finding ways to process the data into actionable inspection deliverables that greatly improve the quality of the inspections. These inspection deliverables better communicate the inspection results to bridge owners and engineers. Our world is being transformed by technology including drones that can collect; process; store; and analyze large amounts of data and this research is applying the same transformative concepts and technology to improve bridge inspection outcomes.

The ability to collect and utilize large amounts of data is transforming our world. Industries like healthcare, finance, energy, communication, and transportation are finding ways to utilize data to improve people’s lives. Processing software and inspection-specific asset management platforms are giving asset owners the ability to utilize this data to accelerate their ability to effectively manage these important assets. The Building Services Section (BSS) owns and operates over 900 individual buildings at over 250 sites throughout Minnesota. BSS explored ways to collect and process as-built data for their sites and buildings with imaging and scanning technology. The data was collected with spherical cameras, handheld cameras, laser scanners, and drones. This research demonstrates the significant advantages of implementing building and site scanning and shows that the technology has many benefits. This research project identified scanning technologies, processing, and data storage options and documented these workflows. The cost information was analyzed to determine which technologies are cost-effective and how new technologies compare to existing methods.