A year after the Key Bridge collapse, the National Transportation Safety Board is urging the owners of 68 bridges across the U.S. to assess their vulnerability to collisions. This moment also presents an opportunity to fundamentally rethink the state of the practice for assessing the health of our nation’s bridges and ensure agencies target taxpayer funds to the bridges that most need repair.
In the days after the Key Bridge collapse, questions were swirling on the state of repair of our bridges and what could be done differently to avoid a bridge collapse. But in the year since, the number of bridges classified as in poor condition has ticked down less than 1 percent according to the U.S. Bureau of Transportation Statistics.
This is not the first bridge collapse in recent history: The Silver Bridge collapse, between West Virginia and Ohio in 1967, brought about the development of the National Bridge Inspection Standards. After the 1980 Skyway Bridge collapse, infrastructure design was altered for future projects to create structural redundancy and fortification. But are our leaders motivated to take similarly bold action today?
A year after the Key Bridge collapse, the National Transportation Safety Board (NTSB) is asking states to revisit collision vulnerability assessments of 68 bridges scattered across 19 states. They are also recommending that FHWA, the U.S. Coast Guard and the U.S. Army Corps of Engineers provide guidance to bridge owners on how to reduce the risk of vessel collision. Congress should require this, if the guidance is not forthcoming in the near term.
However there is a broader problem: several past bridge collapses were the result of problems undetected by bridge inspections or from DOTs failing to heed the problems identified. In the case of the 2007 I-35W bridge collapse in Minneapolis, the NTSB determined that the bridge failed because of design errors, subpar components, and bridge modifications that adversely affected bridge load capacity. These critical flaws were not caught by bridge inspections, and the NTSB recommended changes to the inspection regime.
In the 2013 I-5 Skagit, WA bridge collapse, the NTSB determined that repeated overhead bridge structure damage was due to low clearance truck strikes and no additional warnings or countermeasures to avoid future strikes. Nine of the 10 inspections before the collapse showed high load bridge strikes, but nothing was done in response to these repeated warnings.
In the 2017 I-85 bridge collapse in Atlanta, the NTSB determined flammable materials that had been improperly stored for five years under the bridge led to an excessive heat fire, impacting the structural integrity of the bridge. The presence of these flammable materials was overlooked by bridge inspectors and not included in their inspection.
Lastly, in the 2022 Pittsburgh Fern Hollow Bridge collapse, the NTSB determined poor quality inspections led to a failure to identify fracture-critical issues and incorrect load rating calculations. They also found insufficient oversight of the City of Pittsburgh’s bridge inspection program by the Pennsylvania Department of Transportation.
These bridge inspection protocols heavily rely on visual inspection, theoretical calculations, limited training and recertification of inspectors, and “engineering judgment” to determine the bridge’s health. In the earlier examples, that approach undercompensated the bridge’s respective poor health and collapse vulnerability. In other cases, bridges are being weight restricted for fear of structural issues when that is not, in fact, the case. For example, 10 bridges with load restrictions in Nebraska were load tested in 2021 across three counties using load testing sensors to emulate loads and assess the bridge’s response. As a result, six of those bridges had their restrictions removed. The standard visual inspection found conditions to be worse than they really were.
We are identifying bridges in need of immediate repair while not recognizing critical needs elsewhere, meaning we are not targeting funding correctly. This is all happening while agencies are spending funds on new roads and bridges that further stretch our resources.
Using technology like load testing sensors (which are widely available and relatively inexpensive) can more accurately assess and identify structural issues invisible to the naked eye. Pairing visual inspections with frequent data collection via sensors can better identify bridge health issues and result in proactive maintenance This fix it first approach would lead to few-to-no bridges in poor condition and no bridge collapses. Furthermore, there is a need to support robust and frequent bridge inspector training, to keep current with the required skillsets and tools to assess bridge health.
Looking ahead to the next surface transportation reauthorization, it’s not just about securing more funding—it’s about getting more from every dollar. The next federal transportation bill must set a new standard, prioritizing modern tools for accurate assessments, diligently trained inspector workforce, and a fix-it-first approach to ensure resources go where they’re needed most.
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