Non-Destructive Testing Methods for South Dakota Structural Inspection

Problem Description: Structures are a critical component of the transportation network. As they age, deteriorate, and approach or exceed their operational capacities, effective condition assessment becomes increasingly vital. Inspections play a central role in identifying rehabilitation needs, monitoring deterioration, and ensuring safety and long-term performance. Over the past several decades, nondestructive testing (NDT) technologies have emerged as alternative tools for structural inspection. These methods may offer safer and more efficient alternatives for assessing structural integrity, possibly reducing the time required to detect, analyze, and diagnose a wide range of concerns. While NDT technologies have numerous applications for structural inspections, SDDOT has identified two primary areas where these technologies could offer the greatest benefit during inspections.
The first area is the detection of voids adjacent to buried structures. These voids typically form due to soil erosion, settlement, and water movement through the backfill material surrounding the structure. If left unchecked, they can migrate upward into the roadway base course and surfacing, creating the potential for catastrophic traffic incidents such as sinkhole formation or wheel punch-through. Currently, there is no reliable inspection methods available to quantify the void volume or determine the extent of upward migration toward the roadway surface. Furthermore, many small structures on the SDDOT system are not routinely inspected, meaning voids often go undetected until problems arise. A network-level inspection tool could help identify these issues early and prevent potentially devastating incidents.
The second area is the detection of deck delamination. Traditionally, SDDOT bridge inspectors have supplemented visual inspections with manual techniques such as chain dragging and hammer sounding. While these methods are often considered the "gold standard" for accuracy, chain dragging can be subjective, especially for less experienced inspectors. In high-traffic areas, it can be difficult to distinguish subtle differences in sound, and inspectors are exposed to hazardous traffic conditions for extended periods.
SDDOT is interested in exploring additional NDT applications for structural inspection as well; however, the previously discussed concerns remain the highest priority. There may be the potential for a single NDT technology to address multiple inspection challenges. This could improve efficiency and reduce costs. For all applications presented, SDDOT seeks guidance on selecting NDT methods that can assess structural conditions both on a network-wide basis and for individual projects. These methods should complement traditional inspections and provide engineers with better data for short and long-term planning. Although substantial research exists on individual NDT techniques, uncertainties remain regarding their defect-detection capabilities and the reliability of collected data. These challenges complicate adoption decisions and lead to variability in how agencies apply NDT in the field. This study aims to clarify how, when, and where State DOTs employ NDT methods for highway structure inspection. The objective is to understand current practices, available technologies, identify gaps, and determine which NDT technologies will provide the greatest benefit to the agency's inspection program.
Proposal Deadline: Proposals are due to the SDDOT by 5:00 pm CDT on Thursday, March 19, 2026. This deadline is firm. Extensions will not be granted.
Proposals must be submitted as an e-mail attachment in Portable Document Format (PDF) not exceeding 14MB. The email must be addressed to andy.vandel@state.sd.us and margo.mcdowell@state.sd.us. Proposers should send the e-mail using "Delivery Receipt" and "Read Receipt" options to verify successful delivery.
Proposal Guidelines: Proposals must fulfill the requirements listed in the document entitled RESEARCH PROPOSAL PREPARATION, SUBMISSION, AND EVALUATION and dated October 23, 2025.
Proposal Evaluation: Proposals will be evaluated by a technical panel knowledgeable in the problem area. Selection will be made in consideration of criteria listed in RESEARCH PROPOSAL PREPARATION, SUBMISSION, AND EVALUATION.
Project Management: Margo McDowell is responsible for the management of this project and can be reached at margo.mcdowell@state.sd.us to answer inquiries.