The increasing costs of bridge inspections are a concern for the Minnesota Department of Transportation (MnDOT). Collins has been working with MnDOT since 2015 to study the effectiveness of unmanned aircraft systems (UAS) in the execution of bridge safety inspections. The research study is currently in its third phase.
The use of unmanned aircraft systems (UAS) has been shown to reduce costs, improve the quality of bridge inspections, and increase safety. The UAS can deploy a wide range of imaging technologies including high definition still, video, and infrared sensors; and data can be analyzed using 3-D imaging software.
Phase I of this demonstration project used UAS technology to view four bridges at various locations throughout Minnesota. The project investigated the technology’s effectiveness for improving inspections as compared to other access methods, and its use as a tool for interim and special inspections. Current and proposed Federal Aviation Administration (FAA) rules for UAS were investigated to determine how they relate to bridge safety inspections. Different UAS technologies were investigated to evaluate current and future capabilities as they relate to bridge inspection.
The four bridges were of varying sizes and types and were studied using a UAS after a detailed fieldwork plan was prepared for each bridge. The plan addressed safety, FAA rules, and inspection methods. Several imaging devices were tested and various data were collected in the field including still images, video, infrared images, site maps, and 3-D models of bridge elements.
Phase II looked at twenty-one additional bridges in Minnesota including a large steel through arch, a steel high truss, a large corrugated steel culvert, and a movable steel truss. The UAS’s performance was compared to the industry standard hands-on inspections. Each method was evaluated by focusing on the differences in access methods, data collection, and the ability to be used as a tool for interim and special inspections. FAA rules were explored to determine how practical they were in regards to UAS bridge inspection applications. Before UAS fieldwork began on any of the selected bridges, detailed investigation and safety plans were prepared for each structure. Site specific plans addressed safety, potential hazards and how to mitigate them, current FAA rules, and inspection methods.
Several imaging devices were tested including still image, video, and infrared cameras. After the data collection was completed, data was processed through Pix4D software supplemented with other imaging software to generate 3-D model and maps.
Phase III (in progress)
The Phase III study includes approximately twenty-five bridges, and includes the use of a collision tolerant UAS. Collins is collecting imagery at the selected bridges to evaluate the technology. The UAS will be used to inspect previously identified deficiencies and evaluate the ability to identify deficiencies using photos and video. For more information, please visit MnDOT Research Services & Laboratory.