This workshop presents the state of the art in acoustic imaging for underwater bridge inspection. Presentations explore the advantages and disadvantages of available technologies, necessary qualifications for technicians, practical limitations in technologies to supplement and augment inspection by divers, and real-world examples of acoustic imaging in underwater bridge inspection.
The latest trends in acoustic sonar development offer unprecedented resolution and operator control for underwater inspection. These advancements afford engineers and scientists greater flexibility in deployment procedures and logistics from a variety of platforms. In addition, these improvements further minimize the level of insitu observations historically required for structural analysis, resulting in lower costs and increased safety. This presentation provides an overview of current methodologies along with their respective tradeoffs.
The underwater bridge inspection industry is evolving to take advantage of various sonar tools when conducting underwater inspections. Recent work completed by FHWA and other agencies as well as updates to the Manual on Bridge Evaluation (MBE) will be discussed. General advantages and disadvantages of the technologies will be evaluated and specific examples of how certain states are implementing and taking advantage of these policy changes will be demonstrated.
As sonar technologies improve, interest in applying these tools for underwater bridge inspection is increasing. While the capabilities, standards, and processes are well-established for bathymetric surveying, sonar use for identifying important characteristics relevant for underwater bridge inspection is evolving. FHWA, working with several states, developed and implemented a series of field tests to evaluate the capabilities of sonar in underwater bridge inspection. This presentation provides an overview of the field testing and results. The field testing evaluation focused on: 1) identification of relevant underwater features, 2) performance in adverse environments, 3) data collection/reporting time, 4) equipment costs, and 5) personnel requirements.
Current sonar and positioning technology has enabled bridge inspectors to perform more than just hydrographic surveys. This presentation will discuss the different uses of multibeam sonar for underwater inspection including hydrographic surveys and imaging. Additionally, it will highlight the assembling of survey and imaging data into digital models which allows for the comparison of surveys for scour and point cloud models of substructures. At the conclusion of the presentation, attendees will have an increased awareness of capabilities and limitations of the technology to aid in improving safe, effective, and efficient underwater assessments.
One of Atherton's first commercial dives to inspect a bridge pier was in the Fraser River - zero visibility and high current. In hindsight, the dive was a disaster. Atherton had NO idea where he was on the structure, limited insight as to its condition and when asked the size of the scour hole it was - at best - a 'guestimation.' The introduction of high-resolution scanning sonar changed the whole underwater inspection model. This presentation focuses on the benefits and limitations of using side-scan and scanning sonar for underwater structural inspection.