Bridges have been in construction ever since the invention of the first wheeled wagon. While the materials and methods of construction have gradually changed over the years, the general structure of today’s bridges remains similar to the ones constructed hundreds of years ago.
Highway bridges are built to last for up to 80 years on average. The lifespan of a bridge will depend on the weight and frequency of vehicles passing over, exposure to adverse conditions, and the regularity of checkups or maintenance conducted on the bridge.
A bridge’s lifespan is also dependent on the kind of materials used to construct the bridge and the structural guidelines followed. In this article, we’ll look at the different types of highway bridges and their average lifespans.
The Lifespan of a Highway Bridge
The Romans built their bridges to last, well, forever technically. And they managed to do that to some extent.
For example, the Ponte Pietra, the oldest bridge in Verona, Italy, was built back in 100 BC! It was made from travertine and brick and has been partially reconstructed only once since its completion.
Of course, with the weight of today’s vehicles and the frequency with which highway bridges are used, it would be impossible to construct a bridge that lasts several centuries.
On average, the life expectancy of today’s highway bridges is anywhere between 75 and 100 years, with gradual changes or modifications in the interim.
With the right improvements, highway bridges can be made to last even longer. The lifespan of a highway bridge will also depend on various factors that impact the design and construction of the bridge.
- The combination of materials used.
- Exposure to harmful materials, like road salt.
- Frequency of inspections to determine the health of the bridge
- Number and weight of vehicles passing on the bridge
It’s a combination of these factors that determine how long a highway bridge will last in today’s environment. On average, most well-built bridges today last up to 80 years, with deterioration occurring on the main body of the bridge rather than its serviceable components.
One of the prime determinants of bridge longevity is the material used to construct the bridge. Certain bridges, made with sturdy, reliable materials, are sure to last longer than others.
Concrete bridges are pretty famous as there’s a lower cost involved in their construction. Additionally, it’s cheaper to procure concrete and relatively straightforward to build with it, making it a favorite material of bridge builders looking to make large profits.
However, concrete bridges require more frequent inspection and servicing of the main body and other structural components.
Most concrete bridges tend to last between 50 and 70 years, with frequent inspections in between.
And when constructing with concrete, quality is of prime importance. Using low-quality concrete can lower the lifespan of a highway bridge by years, if not decades.
Luckily, materials like reinforced concrete have lengthened the lifespan of highway bridges made with concrete.
While stone is barely used to make bridges anymore, it happens to be one of the most reliable materials used in construction. Medieval monarchs built stone bridges that have withstood the test of time and are used even now in certain places.
However, stone is a complicated material to work with and significantly shoots up the cost of construction. As such, it’s impractical to build highway bridges out of stone in today’s rapidly changing industrial environment.
Of all materials, steel is the most popular and widely-employed raw material used in bridge construction today. Steel is malleable and versatile, making it ideal for use in several structural and main-body components of a highway bridge.
Steel weighs less and can be transported easily. This material also requires a smaller foundation and hence is much less expensive to work with than the other materials generally used for construction.
Today’s steel bridges are made to last for well over 100 years, and thanks to the ease with which steel can be manipulated, these bridges can be easily serviced and made to last even longer when necessary.
How To Improve the Lifespan of a Bridge
As mentioned at the beginning of this article, the general structure of highway bridges hasn’t been altered much since they were first constructed. However, it is possible to further extend the lifespan of a bridge by following a few practices.
Researching Structural Systems
Today, the construction industry offers a variety of materials to work with on large-scale construction.
The introduction of reinforced concrete, high-strength steel, and fiber-reinforced polymer has allowed us to build bridges that last longer than ever before.
But to truly take advantage of these superior construction materials, we need to improve our understanding of structural systems.
By optimizing structural shapes, design elements, and specific procedures in construction, we can take full advantage of these superior materials and build longer-lasting bridges.
Monitor Bridge Health
Periodically monitoring bridge health is essential to prolonging the life of highway bridges. This type of monitoring is possible thanks to new data collection tools and techniques that can monitor every aspect of a bridge and see where it falls short of standard norms.
The difficulty here is assessing what data to pay attention to and developing innovative solutions to tackle issues that crop up.
It’s also imperative to research the different environmental aspects that decrease the service life of a bridge. A builder can figure out ways to deal with these ecological processes and mitigate the detrimental effects by understanding the different aspects involved.
Improve Bridge Construction Speed
Today, traffic demands outstrip the pace at which a highway bridge is built. As such, most highway bridges have no off time where they are free from traffic and can be inspected and repaired appropriately if necessary.
Perhaps the only way to ensure that bridges are maintained regularly is by accelerating the construction of upcoming bridges.
The task for today’s builders is to create techniques that will speed up the construction of bridges. By constructing alternate routes, traffic can be diverted while the more regular highway bridges are being inspected.
Q. What method is popularly used to construct highway bridges?
A. While each builder may have a preferred construction method, the method most frequently used to make highway bridges is the Courbon Method.
Q. Why don’t they use asphalt to construct highway bridges?
A. Asphalt is used in specific types of construction, but it’s not a popular material for a couple of reasons.
- Asphalt adds to the overall weight of the bridge, making it less safe and sturdy.
- Asphalt coverings tend to hide other problems that may occur within the structure of the bridge.
Q. What are the different types of highway bridges?
A. All highway bridges are constructed using different design methods. The most common ones include
Each bridge design comes with its own rules and complications, and some builders prefer specific designs over others.
However, the most popular design is the beam, and it’s widely used in cities across the world. While the beam isn’t the most aesthetic shape, it’s functional, reliable, and easy to build.
The ease with which it can be constructed makes beam bridges the most popular type of highway bridge out there.