C+S August 2023 Vol. 9 Issue 8 (web)

Structures + Buildings

Quality Over Quantity: Today’s Bridge & Tunnel Inspection

Photo Credit: ASNT

By Shane D. Boone

These inspection methodologies can also potentially improve the safety and longevity of the structure(s) while maintaining the safety of inspection personnel. The digitalization of the inspection industry has led to the adoption of new technology and tools for NDT-E personnel to assist in meeting federal inspection requirements. There are currently sixteen recognized methods of NDT-E across a range of industries and for the infrastructure of bridges and tunnels. Visual Testing (VT) is a technique of NDT-E inspection, and it can be utilized as an important method of risk assessment. VT involves the visual observation of the surface of a test object to evaluate the presence of flaws or defects in the material. VT is the most used test method in the infrastructure inspection industry, as most test methods require personnel to visually inspect the surface of a part prior to inspection. There are two visual testing techniques: direct, which involves the use of optical instruments for the inspector to physically observe the material; and remote, which involves the use of borescopes, drones, cameras, and computer-assisted viewing systems to identify possible issues within a structure. Visual Testing is a vital first step in the routine inspection of any element of infrastructure, including bridges and tunnels. With the constant adoption of new technology in inspection software, the method and quality of data collection can be consistently improved. High resolution image (HRI) data collection via drone or other traveling vehicle can allow for a thorough record of an asset’s existing surface condition, that

It’s no secret that the aging infrastructure across the United States poses a risk to the safety and serviceability of our nation’s structures. While other industries have implemented preventative maintenance methodologies for preservation of their assets, the transportation infrastructure industry has lagged and primarily utilizes a retroactive approach. An example, Amtrak’s B&P Tunnel Replacement Program, seeks to replace the nearly 150-year-old B&P Tunnel in Baltimore, MD that is currently used to transport thousands of commuters daily along its Northeast Corridor (NEC). The decrepit tunnel is plagued by a range of issues, including excessive water infiltration, structure deterioration, and floor sinkage. Had the tunnel been properly inspected and evaluated on a routine interval throughout the 20th century, emerging flaws and defects may have been addressed in a proactive effort to prolong the tunnel’s lifespan. While the current National Bridge and Tunnel Inspection Standards (NBIS and NTIS, respectively), recognize a proactive inspection process, there exist technologies that could improve the data gathered such that more informed decisions could be made by asset owners. Nondestructive Testing and Evaluation (NDT-E), is a form of inspection that can be performed without impacting a structure’s integrity. Cracks, corrosion, discontinuities, or structural degradation, for example, can be identified long before they are reported with visual inspection. Utilizing NDT-E can provide key structural and material data allowing stakeholders of transportation infrastructure to better allocate their funding through more effective and efficient inspections.




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