Be sure to read the January 2023 Materials Evaluation special Technical Focus Issue on highway infrastructure inspection and evaluation. This open-access issue was guest edited by Sreenivas Alampalli, PhD, PE. Following is Alampalli’s introductory letter to this issue.
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by Sreenivas Alampalli, PhD, PE
It is a pleasure to share the focus issue on highway infrastructure inspection and evaluation with all of you. Highway bridges have been inspected using visual testing (VT) methods for more than 100 years, but the extent, frequency, personnel qualifications, and quality of these inspections have varied significantly depending on the owners. It should be noted that in bridge management terminology, the term “inspection” refers to (field) visual inspection of structures, which is equivalent to visual “testing” as used by ASNT. The word “testing” mostly refers to the use of NDT methods such as magnetic particle testing (MT), liquid penetrant testing (PT), and ultrasonic testing (UT), as well as to static and dynamic load testing.
The roots of current structured inspections mandated by Federal Highway Administration (FHWA) can be traced back to the collapse of the Ohio River Bridge (known as the “Silver Bridge”) in 1967, which killed 46 people. This led to the establishment of the National Bridge Inspection Standards (NBIS) that defined structured inspection of publicly owned bridges nationwide, including inspection frequencies and qualifications. NBIS have been updated since then based on lessons learned from various failures—for example, the collapse of Schoharie Creek Bridge in New York State in 1988 led to underwater inspections at regular intervals. Until recently, the primary focus of these guidelines has been public safety by avoiding partial or full collapse of structures. Therefore, VT is predominantly used, with other methods used for local characterization of defects as further investigation based on inspectors’ recommendations.
The role of infrastructure in modern societies has changed from being a means to move people and goods from one place to another. Mobility, reliability, economic competitiveness, and security, in addition to safety, are expected by the public and consequently are important performance measures for owners in a resource-constrained environment. This shift in public expectations renewed emphasis on preservation and mobility-focused asset management, meaning finding deterioration and inspection methods that require low service interruptions becomes very important. Therefore, changes to NBIS in recent years have been focused on collecting data for effective and proactive asset management. This issue focuses on recent changes and developments in that direction. At the same time, ensuring quality during construction is also important, and there is renewed emphasis on QA/QC of construction using nondestructive testing methods.
This issue has five papers. The first by Alampalli, Jalinoos, and Ailaney discusses recent changes in NBIS in the direction of asset management and preservation focus. They also discuss recent changes in technologies associated with aboveground inspections and corrosion mitigation as a prelude to the rest of the papers. Most failures are attributed to bridge scour; underwater inspections play a major role in mitigating these failures. The following paper by Severns discusses modern underwater inspections that are increasingly reliant upon new technologies and nondestructive testing methods beyond VT (such as UT, MT, and sonar in conjunction with remotely operated vehicles) to gain a broader picture of the asset and its condition, increasing efficiency while lowering risk in the process.
The quality of a completed structure starts with good quality control during construction, and thus the use of quality control during construction to adhere to design specifications is paramount for durability and preserving expected service life. Sanei, Yuan, Moreu, and Alampalli discuss the use of these new technologies for ensuring construction quality and digital history for future management. They illustrate the use of these technologies through a study conducted using an RGBD camera.
While improving accuracy in the detection and characterization of deterioration and defects using NDE methods is essential, improving the speed of NDE data collection and interpretation—allowing economical periodical evaluation—has potential to yield tools for better bridge management. Gucunski et al. provide an overview of the current practice of bridge evaluation by NDE methods, recent efforts to improve the speed of NDE data collection through automation and robotics, and improved condition interpretation through advanced visualization and combined analysis of results of multiple NDE technologies. Similarly, use of advanced multi-sensor robotic platforms, such as uncrewed ground-based systems (UGS) and uncrewed water-based systems (UWS), are also being used increasingly for similar purposes. A futuristic view of using drone-based NDE for elevated structures (bridges, buildings, dams, power plants, tunnels, etc.) is discussed by Chen et al. These systems, including human-robot systems, have the potential to transform bridge inspections in the future to minimize impact to traffic at bridge sites.
I consider the next decade to be a golden era for development and use of NDE technologies in highway infrastructure, including bridges, and am glad to share recent policy and technological changes with all of you. It was great working with ASNT Director of Publications Jill Ross and the authors in this issue. I thank them for their enthusiasm and hard work in bringing this issue to all of you, and I hope you enjoy reading the articles as much as we did in preparing them. We look forward to hearing your comments and opinions on these articles and on this topic in general.
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Author
Sreenivas Alampalli, PhD, PE, MBA, F, ASNT Focus Issue Editor, sreenivas.alampalli@stantec.com
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Papers featured in this Technical Focus issue of Materials Evaluation:
- BRIDGE INSPECTION: Progression of Bridge Inspection Toward Preservation and Corrosion Mitigation for Improving Asset Management
- Underwater Inspection of Highway Bridges–Recent Trends and Technologies
- Advancing Condition Assessment of Reinforced Concrete Bridge Elements Through Automation, Visualization, and Improved Interpretation of Multi-NDE Technology Data
- Aerial Nondestructive Testing and Evaluation (aNDT&E)
- Automated Geometric Quality Inspection of Rebar Layout Using RGBD Data
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