In every state of the United States there are bridges over highways and other roads. Whether you drive a truck, auto or motorcycle, you likely travel on, below or above a bridge almost daily. There are more than 617,000 bridges in the United States. According to the American Society of Civil Engineers (ASCE), 42% of those bridges are at least 50 years old, and more than 46,000, or 7.5% of the bridges, are considered structurally deficient, meaning they are in “poor” condition.
Vehicles make 178 million trips on the structurally deficient bridges daily. As the average age of all bridges continues to increase, maintenance/repair of the deficient bridges has slowed.
The backlog of bridge repairs was recently estimated at $125 billion according to the Federal Highway Administration (FHwA). At the current rate of investment, all of today’s deficient bridges would not be repaired until 2071. Of course, over the next 50 years additional bridges will deteriorate and the task will become overwhelming. While not all are rated structurally deficient, there are nearly 231,000 bridges – in all 50 states – that need repair and preservation work.
The U.S. Senate passed a massive infrastructure bill; it is now being considered in the U.S. House of Representatives. Of the $1.2 trillion in the legislation, less than 10% (about $110 billion) is earmarked for construction of roads and bridges.
Another provision of the legislation would reauthorize the current surface transportation program for five years and build on transportation reauthorization bills that passed out of committees earlier this year.
Over the past 10 years all levels of government have prioritized bridge repairs through investments. This has led to 37 states to either increase or reform their gas tax since 2010. Despite states’ increased investments, however, overall spending on the country’s bridges remains insufficient.
The final infrastructure legislation may change between now and when it is sent to President Biden for his signature. However, the current $110 billion for “roads and bridges” is not enough to fix all the bridges. Moreover, much of the $110 billion will be on the Interstate Highway System and other road projects – not on bridges!
Innovate to get it done
All of the nation’s bridges are continuing to age. Most of the emphasis has moved from building new bridges to maintaining the existing ones. When a new bridge is built, the American Association of State Highway and Transportation (AASHTO) requires new bridges to be designed with a 75-year service life, up from the previous requirement of 50 years. Bridges are being built to last longer due to new technologies, materials, evaluation techniques and construction methods.
Operations and maintenance
Bridges across the United States are generally unique structures; all are deteriorating at their own pace and are in need of specific treatments at specific times. To help manage this process, the federal government requires states to develop and use Transportation Asset Management Plans (TAMPs).
TAMPs are meant to outline a systematic, data-based approach so that states can manage their inventories. Each TAMP is required to predict and set targets for the bridges that will be in good or poor condition over the next 10 years.
However, more can be done. The ASCE promotes a prioritized list to rehabilitate and preserve bridges in fair condition. The organization’s reasoning is simple – bridges in fair condition can often be “preserved at a fraction of the cost of replacement if the work is performed in a timely manner.” Moreover, this approach could reduce the number of structurally deficient bridges to below 5% of the total number of bridges, “decrease the maintenance backlog, and address the large number of bridges that have passed or are approaching the end of their design life.”
Many of the country’s older bridges are susceptible to extreme weather events and flooding. These events can result in overtopping, washout and other storm-related damage. Nearly 21,000 bridges are in danger of overtopping or having their foundations undermined during extreme storm events.
States are also being urged to prioritize investments on those bridges that are most critical (carry the highest daily traffic volume, are on critical freight corridors or are on evacuation routes).
In a related article, FreightWaves’ Nick Austin wrote about “America’s scariest bridges for truckers.”
Some of the worst bridge collapses in the U.S. are profiled in Part 2 of this article.