Engineers are experimenting with a new technology to prevent infrastructure disaster. That's why Minnesota, a land of many lakes and some 20,000 bridges, started drone experiments. At the fractional cost of traditional inspection methods, unmanned aerial vehicles (UAN) can scan whole bridge lengths and nose into hard-to-reach cracks. Drones have been announced in bridge inspection as the next big thing.
Drones have become an integral tool to save time and money and to report on project progress. Drones can snap thousands of high-resolution images near aging trusses, piers, and bearings. Special software then stitches these images into 3D models that can be examined on computers by engineers; a single click on a small detail can call up a photo library stretching back in time—a useful reference for timing the deterioration rate of a structure. Capacity and technology in these devices have advanced rapidly over the past five years, and the industry is testing their value and exploring how to best use drones in specific applications. Furthermore, as more automation and safety features come on board, costs for drones and related services drop significantly.
The associated costs and dangers continue to remain a challenge regardless of the method used to perform the work. AWPs and snoopers are likely to require lane closures, and the equipment itself is expensive to maintain and operate, while ropes need a high level of training and expertise for safe use. A two-phase MnDOT/Collins research project started with these issues in mind, which is currently in its second phase. This study's final objective is to identify the bridges where UAV inspection could provide the close details necessary for a thorough, reliable and cost-effective inspection.
The team is currently working with another UAV, the senseFly albris (formerly called eXom), for phase-II. This is specifically designed for work on high-detail inspection. Researchers chose this system to re-inspect various types of bridges, including bridges with very confined spaces, such as culverts and box girders, and to use the thermal camera of the albris to conduct deck delamination assessments.
In recent years, drone technology has come a long way, with companies like senseFly dedicating research and development to developing drones that are specifically designed for such work. Current FAA regulations slow down the adoption of UAVs for bridge safety inspections as the time needed to obtain approvals is substantial and cost prohibitive. However, the proposed FAA rules are set to remove many or all of these barriers in the hopefully near future for widespread adoption.