The secret life of bridges
A look at the state of America's unsung infrastructure heroes
A look at the state of America's unsung infrastructure heroes
Investing in infrastructure has, generally speaking, been a popular and productive decision by the United States government. It creates well-paying jobs, makes the country safer, and boosts the economy in a number of direct and indirect ways. That explains how, even in today's contentious times, a bipartisan, one-trillion-dollar infrastructure bill was passed by the United States Senate on August 10, 2021.
When thinking of infrastructure spending, it’s the brand-new, grandiose, far-reaching projects that often come to mind first—the kinds of things that entail a ribbon-cutting ceremony. However, it’s the upgrades to existing infrastructure, while less buzz-worthy and photogenic, that can provide the biggest return on investment. One type of infrastructure in particular carries an outsized importance: Bridges.
If you’ve ever traveled in the U.S., you’ve almost certainly been across one or two of them—if not several hundred. From the vermilion arches of the Golden Gate to myriad industrious, commerce-sustaining highway overpasses, the bridges of the United States are a beacon of mobility, a triumph of modern engineering, and a critical component of the nation's expansive ground transportation infrastructure.
Bridges are so ubiquitous that they're easy to take for granted. Think about the last time you crossed one. Do you remember what it was made of? Do you know when it was built? Or what kind of condition it was in? How about the last time it was repaired or refurbished?
It’s perfectly normal to be unable to answer these questions, but they do make you wonder.
As these patterns reveal, bridges play an enormous but largely unsung role in our economy, commerce, and everyday life. It’s good to know that someone is paying attention to their well-being.
But to really understand the story of bridges—and what it takes to maintain them—it helps to examine their evolution and historical spread across the country.
Among the key takeaways from this temporal- and material-based analysis is that the vast majority of bridges are not, in fact, grand icons spanning dramatic natural features. Rather, they service a much more mundane and less glamorous purpose: the efficiency and expediency of everyday transportation and commerce, in the form of multilane highways.
Another observation is the modern prevalence of concrete as the primary construction material for bridges. Concrete, while initially cheaper and more environmentally sensitive to build with than, say, steel, tends to require an ongoing, more proactive care regimen to maintain its strength.
The total estimated cost to bring all bridges up to good condition exceeds $125 billion. At our current rate of investment, it would take another half-century to make all of the necessary repairs and rehabilitations. The bridges in poor or even fair condition require more prompt attention, which raises the question of how to strategically prioritize bridge repairs and refurbishments.
Cross-referencing bridges in poor condition with those approaching a century or more in age can help pinpoint bridges may be structurally obsolete and are nearing (or have already passed) the end of their design life. Repairing old bridges is typically costlier than applying preventative care to newer bridges, especially for those that have not yet crossed the threshold into poor condition.
A key question is where the money to perform sufficient repairs will come from. A lack of reliable, dedicated funding for bridge repair is an issue for virtually every municipality, county, and state. This uncertainty can lead to inefficient stopgap measures to maintain safe roads and bridges.
An extreme example of one such measure can be found in Pittsburgh. In the late 1980s, a nearly 70-year-old bridge began to crumble onto the Interstate highway below it. City officials initially fastened nets below the bridge to catch falling debris. The nets were not completely successful, however, so in 2003 the city erected a second, makeshift bridge under the existing bridge to provide additional protection to motorists. This solution made do for over a decade, until, at last, the old bridge was taken down and a brand new one built to take its place.
The old Greenfield Bridge in Pittsburgh with its attendant mini-bridge underneath (left) and its just-completed replacement pictured in 2017 (right).
The future holds some promise for our aging bridges: Should the trillion-dollar infrastructure bill that’s currently on the table ultimately become law, it will represent the nation’s largest financial commitment to infrastructure since the New Deal. Approximately $110 billion of that expenditure would be earmarked for roads and bridges, the largest such promise since FAHA spawned the Interstate Highway system.
If you're interested in sinking your teeth into the bridge data used for this story, take some time to play with the map below. At smaller scales, the map shows the proportion of bridges in each county that are in poor condition (lighter shades indicate a higher percentage of poor-condition bridges). Click on a county to see some basic facts about its bridges. Zoom in to discover and explore hundreds of thousands of individual bridges.