America’s infrastructure is facing a crisis, with the country’s aging bridges standing as a symbol of its outdated and vulnerable state. According to a recent report by The New York Times, nearly a quarter of the nation’s bridges were constructed before 1960. However, as climate change intensifies, these old structures are increasingly under threat.
“The bridge crisis is now specifically tied to extreme weather events. These are not things that would happen under normal climate circumstances. These are not things that we’ve ever seen at this rate,” explained, Paul Chinowsky, a civil engineering professor at the University of Colorado Boulder.
A significant factor contributing to the problem is that these bridges were not designed to handle the rapid temperature fluctuations. The natural expansion and contraction of metal in response to these temperature shifts create additional stress on already deteriorating structures. The consequences of these shifts are becoming more evident, with crumbling trusses, cracked asphalt, and eroding foundations becoming more frequent.
This concern is not new. A 2019 report published in the journal PLOS ONE warned that 25% of all steel bridges in the U.S. are at risk of collapse by 2050. Despite years of discussions, real action was delayed. However, progress began in 2021 when the bipartisan Infrastructure Investment and Jobs Act was passed, allocating $110 billion to roads, bridges, and other transportation projects.
In July 2024, U.S. Transportation Secretary Pete Buttigieg announced $5 billion in funding aimed at repairing or replacing 13 key bridges across 16 states. Buttigieg acknowledged the urgency of the situation, stating, “For too long America let bridges fall into disrepair, which left people less safe, disrupted our supply chains, and cost people time and money.”
However, the warming climate continues to exacerbate these structural issues. Jim Tymon, executive director of the American Association of State Highway and Transportation Officials, told The New York Times that scientists, engineers, and agencies are now working quickly to introduce climate-resilient standards for future bridge construction. But the existing challenges are daunting.
In addition to the physical stress placed on bridges by extreme heat and temperature fluctuations, increased rainfall presents another serious threat. Torrential rains and flooding, like those seen in Vermont in July 2024, have the potential to wash away entire bridges.
Furthermore, heavy precipitation accelerates “bridge scour,” a process where soil surrounding a bridge’s foundation erodes, weakening its stability.
Swollen bridge joints, caused by fluctuating temperatures, are also a major concern. Steel bridges are designed to bend slightly under heavy loads to evenly distribute weight, but when the metal expands due to heat, these joints become rigid, leading to a greater risk of overloading the structure beyond what it was designed to support.
Part of the issue stems from a long-standing decline in public investment in infrastructure. Federal Reserve data indicates that public spending on infrastructure in the U.S. has decreased by 40% since the 1960s. This reduction in funding has only worsened the state of the country’s bridges. Now, with the added pressure of climate change, the need for immediate and robust action is undeniable.
With scientists and engineers working to implement new climate-resilient designs, the hope is that these aging structures can be protected before more catastrophic collapses occur. However, the country must act as soon as possible to protect its economy and the safety of its citizens.
