Steel Corrosion in Underground Transportation Infrastructure

Corrosion imposes a significant threat to our aging transportation infrastructure, including bridges, highways, railroads, and a multitude of subsurface structures such as metallic culverts, drainage pipelines, reinforced soil structures, and metallic deep foundation systems that support our transportation network. The annual cost of corrosion for highway bridges in the US is estimated to be between $6.3 and $10.15 billion. Corrosion of buried steel remains one of the most insidious challenges due to the uncertainty associated with its estimates. This uncertainty grows exponentially with time, making corrosion estimates quite worrisome and challenging for transportation asset management in the long term, especially since buried steel structures cannot be inspected visually. Recently, the National Academies of Sciences, Engineering, and Medicine (NASEM) published a report in 2023 titled “Corrosion of Buried Steel at New and In-Service Infrastructure” documenting the research gap in modeling and estimating corrosion of buried steel. The report emphasizes the urgent need for further investigations to improve the current outdated corrosion models, which were developed primarily using data from the 1950s. Improving our understanding of long-term corrosion and our ability to quantify such corrosion based on the continuously varying subsurface environment will be of great assistance to engineers in evaluating the service life of existing underground steel transportation structures as well as in the future designing of new structures. This proposed research aims to improve corrosion estimates based on the key subsurface conditions contributing to corrosion through a unique experimental program that shall produce data necessary to quantify the impact of various corrosive environment variables on steel buried in granular soils. The specific objectives of the proposed project include (1) selection of corrosion parameters and ranges; (2) element-scale testing in controlled constant and varied conditions, (3) discussion of practical implications and development of recommendations; (4) training of undergraduate research students in civil engineering to partake in applied research during their undergraduate studies and prepare them for the nation’s current challenges; and (5) development of a final report that documents and disseminates research methods and findings.