In a recently released report, the U.S. Government Accountability Office (GAO) (Washington, DC, USA) is asking the U.S. Federal Highway Administration (FHWA) to better inform state leaders about appropriate corrosion mitigation strategies for bridges.
In all, the U.S. highway system includes approximately 146,000 bridges, according to GAO. Of those, most are made of materials that are susceptible to corrosion and can ultimately cause bridge failure. According to GAO, the percentage of bridges in good condition has declined since 2016.
“The Federal Highway Administration researches factors that affect bridge condition (e.g., corrosion), and provides technical assistance to states,” GAO writes in a September 2021 report. “But state officials we talked to said they need more information about effective corrosion mitigation practices for specific environments and circumstances.” Thus, GAO is recommending this information as part of FHWA's ongoing bridge preservation efforts.
State practices to prevent and manage corrosion vary based on environmental factors and bridge condition, according to the GAO. For example, states exposed to sea water and deicing chemicals may clean bridges to remove materials that could accelerate corrosion.
Four of the five selected states prioritized rehabilitating and replacing poor condition bridges, while the fifth state said it took steps to address corrosion to preserve and maintain bridges in good and fair condition. States are transitioning to asset management practices that emphasize bridge preservation strategies, GAO explains.
However, officials from the selected states said limited information about the effectiveness of specific corrosion practices is a challenge to the implementation of asset management practices. For example, officials from some selected states said they use sealant on bridge decks to prevent corrosion, while officials from another said they do not because they do not know how effective it is.
Role of FHWA
FHWA, which operates within the U.S. Department of Transportation (DOT), helps states address corrosion through research and technical assistance. However, FHWA efforts have generally focused on overall bridge condition and may not meet states’ needs to determine the circumstances in which to use specific practices, according to GAO.
“For example, FHWA’s Bridge Preservation Guide identifies practices that can be part of a bridge preservation approach but does not indicate under what circumstances they are most effective,” GAO writes.
“Although FHWA does not endorse specific practices, officials recognize their role in helping states make well-informed decisions regarding bridge corrosion. As states continue transitioning to an asset management approach, providing information about the circumstances under which different corrosion practices are most effective could help states make best use of their resources.”
As a result, GAO is recommending that FHWA’s ongoing bridge preservation efforts include activities that focus on addressing the challenges that states face with determining the circumstances under which specific corrosion practices and materials are most effective.
DOT says it agrees with this recommendation and provided technical comments, which are incorporated in the GAO report.