What are the differences between bridge and viaduct ?
How to make difference between a viaduct and a bridge? This is a question that seems simple and yet many people do not know how to explain the differences between these two structures.
In this small article we will therefore look for what differentiates bridges and viaducts. We can finally shed new light on an issue that has crossed our minds!
The nature of crossed gap
In the collective imagination, we can distinguish 2 structures by what they allow to cross. While the bridge would be used to cross an area of water such as a stream or a river, the viaduct would have been developed to cross large spaces of land including obstacles or depressions (large differences in ground levels).
If this explanation seems plausible, it is not the element which makes it possible to differentiate the 2 structures.
The type of structure
In the public works sector, metal structures such as bridges or viaducts are made using the same materials (concrete, reinforced concrete, metal, etc.), the same know-how and the same methods of construction and assembly. Strictly speaking, there are no structural differences between bridges and viaducts. Just as there are different types of bridges, you can find viaducts with girders, cable-stayed or suspended viaducts…
The number of obstacles to cross
As a rule, a bridge is installed when you want to override an obstacle, whether it is natural (ditch, stream …) or created by humans (highway, railway …). Since the obstacle is small, all that is needed is a bridge consisting of a small number of spans to cross it.
However, when there are several obstacles that don’t allow the direct pass through a simple road, we no longer speak of a bridge but a viaduct. These “special” bridges are indeed made up of a greater number of spans and can thus ensure the pass of a roadway over a greater distance. In France, the most emblematic viaduct remains the Millau viaduct.
In summary :
To conclude simply, viaducts and bridges are structurally similar and fulfilling the same mission: to cross all kinds of obstacles to connect two portions of road. Nevertheless, the viaduct, architectural construction often impressive, is distinguished by its length, and in some cases by its height. The Millau Viaduct, inaugurated in France in 2004, is currently the world’s tallest structure with pylons up to 242 meters below the roadway and a maximum height of 343 meters at the top of the structure. This viaduct bears the nickname “Bridge in the clouds”, or “Clouds bridge”!
“The Viaduct is a particular bridge that extends well before and well after the stress it must straddle while the bridge ends immediately after the crossed obstruction.”
Viaducts built by Matière®
In France there are nearly 210 viaducts throughout the country. Among all these remarkable constructions from a civil engineering point of view, discover some of the viaducts built and commissioned by Matière® !
In Charente, in the municipality of Chabanais you can take the Viaduct on the Vienne river. This 348-meter-long mixed structure was installed by launching over the Vienne, a municipal road and a railway line. This double-beam bridge, or viaduct, includes 6 piles made of reinforced concrete box posts and 2 decks with a maximum span of 190m. It is a structure of nearly 3600 tons.
The Chabanais road structure was inaugurated in 2012 and supports thousands of cars and trucks every day.
This bow-string bridge for railway use is also considered a viaduct and was built by the Matière® teams in 2015. This metal structure allows a range of 90m and is 19 meters high. You will be able to admire the Viaduct of Lez in Lattes during your next visit in the Hérault, south of the beautiful city of Montpellier!