can potentially be compared year over year. While this process can be implemented fairly easily, the current lack of standards related to the image data collection and subsequent resolution of the final deliverable has potentially caused a slower implementation of these types of tools. Federal Regulations from the Federal Highway Administration Close, visual inspection of bridges and their spans is the first step of federally mandated bridge inspection. This is set by the NBIS and NTIS, which incorporate inspection regulations and protocol for bridges and tunnels, as noted above. Visual Testing is implemented with routine, hands-on inspections as well as in-depth inspections when potential flaws and defects are observed. Inspection personnel must possess certain qualifications, including completion of a Federal Highway Administration (FHWA)-approved comprehensive bridge inspection training course. Inspectors must also take a refresher course every 60 months to ensure their skills are up to date with the latest technology and tools. The current inspection standards for bridges are calendar based. Each bridge must be inspected at regular intervals not to exceed 24 months. Depending on the integrity of the bridge, some need to be inspected once every 12 months while others can expand their inspection frequency to once every 48 months. Importance of New Technology in Visual Inspection As mentioned above, HRI can be utilized to create visual records, including 3D models of a structure, that can be used to visually track how structural elements change over time and if flaws and defects emerge between inspection cycles. These 3D models can be used year after year to compare versus having still images taken from different vantage points. In the last decade, methodologies have been improved to allow data collection at highway speeds, via drone, and fixed wing aircraft to capture visual data that can be stitched together into orthomosaic images. This has resulted in the creation of automated algorithms for crack, spall, and patch detection in concrete structures and surface crack and corrosion detection in steel structures. This enables a more efficient, reliable, and repeatable inspection which ultimately saves on cost and time, while also reducing the impedance on the traveling public.
VT is not just about efficiency, but also safety and effectiveness. It adds great benefit to the inspection process by reaching areas that are otherwise inaccessible or dangerous to access while maintaining the safety of inspection personnel. In addition to removing the potential safety risks when inspecting difficult to reach areas, utilizing HRI increases effectiveness through image resolution and identifying discontinuities. While there have been many advances in the collection and processing of HRI, there are currently no standards for the resolution of the data captured and subsequent deliverable. This causes a challenge for inspectors as they then must recollect and restitch the data, incurring more time and cost. This could be avoided by setting a standard for the resolution of images captured from the inspection while still allowing inspectors to select their tools. This standard should match that required by both the NBIS and NTIS, however, this level of resolution is difficult to achieve and can result in higher costs to the asset owner. Being More Effective with Visual Inspection Visual inspection and supplemental HRI should be utilized to the fullest extent possible by having standard training on new equipment and software as well as standardization of data resolution and deliverables. Properly utilizing these tools can provide asset owners with reliable, repeatable data that can be utilized to improve data driven decision making. With limited resources, these asset owners can implement more efficient inspections that will be critical to our aging infrastructure.
SHANE D. BOONE, PH.D., is the Chair of ASNT's Research Council Infrastructure Committee
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AUGUST 2023 csengineermag.com
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