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.
