Difference Between Bridge and Viaduct

In today's article, we're going to address a topic that many of you may find very interesting and that will clear up any doubts you might have, whether you're a layperson or an engineering professional. We're talking about the difference between a bridge and a viaduct. Do any of you know what they are?

If you already know the difference between these two constructions but are curious to learn more, this post will provide you with valuable information on the topic. We'll explain everything in a simple way, so that everyone can understand it.

In addition to outlining the main differences between a bridge and a viaduct, we'll also define what each of these two structures entails and reveal the most important bridges and viaducts in Spain , similar to those featured in our article on the longest bridges in the world. Now that summer and holidays are here, you might be inspired to visit them.

Bridge: what is it and materials

This refers to a structure built by humans on a depression to connect one point to another . When we refer to a depression, we mean a deep, concave area of ​​land, or one containing bodies of water such as rivers, lakes, the sea, etc.

The main function of bridges is to allow the passage of people or goods, whether on foot or in any type of vehicle. There are pedestrian bridges, and bridges with access for vehicles or trains if they are equipped for it.

Depending on their intended use, they can be classified into different types such as aqueducts , when used for transporting water, viaducts , which we will see later, or footbridges , which are intended for pedestrian traffic.

Safety is paramount in this type of construction; therefore, the structural design must be carried out by professionals in the field. This design must be based on structural calculations that take into account various aspects, such as the construction materials.

Bridges, as we have just seen, can be built from different materials , and depending on which one is chosen, the construction will have certain characteristics.

• If they opt for using wood, they are faster bridges to build and with a not so high cost.. On the contrary, they are usually not very resistant and durable. It is a material that is very sensitive to certain atmospheric agents.
• A stone bridge is much stronger and more durable over time., although its construction is more expensive. It doesn't require much maintenance and withstands different climates very well.
• Metal bridges are the most versatile, as they allow for unique designsThese are quick constructions, but they're expensive. It's important to note that over time, in certain climates or in certain gases, they begin to corrode.
• Lastly, concrete bridges are quick to build, strong and affordable for the pockets of the construction companies. They are very resistant to the action of different atmospheric agents.

What types of bridges can we find?

We've already seen what a bridge is and the different materials it can be built with. Now, it's time to discover the shapes these structures can take depending on the stresses on their structural elements.

• girder bridges: They are composed primarily of horizontal elements supported by pillars or supports. Vertical elements, such as pillars, bear a compressive force. On the other hand, horizontal elements tend to flex due to the weight they support.
• arch bridges: These are structures composed of an upwardly curved section resting on supports or abutments. Two different constructions can be found in this type of bridge. In one, the arch supports the bridge deck, while in another, the arch supports the deck itself, using supports.
• Hanging bridges: In this case, the bridge deck is hanging and is supported by the help of a large number of braces. In addition, two large cables anchored on both sides of the bridge.

Viaduct: what it is and how it is built

The term viaduct is divided into two words: "via" and "duct." The first refers to a road or path, while the second refers to a structure. Therefore, we can say that a viaduct is a structure built for the movement of people, whether on foot or by vehicle.

Generally, these types of structures are quite large, so they are primarily used by vehicles rather than pedestrians. Viaducts are built to connect two isolated points, spanning valleys or other geographical features.

Roman viaducts were built with stone and arches, as we can see in aqueducts . Over time, all of this evolved, especially with the arrival of the railway, so wood came to replace stone due to cost, as wood was a very abundant material.

Currently, the most commonly used materials for viaduct construction are reinforced concrete and steel. One of the main challenges of this type of construction is the lack of supports or the distance to be spanned.

Main differences between bridge and viaduct

Once we have defined what each of these two terms consists of, which seem very similar, it is time to discover what their main differences are and thus, be able to distinguish one construction from another.

The first difference is that bridges are usually built over large bodies of water or obstacles that otherwise prevent passage , thus providing a way to cross them. Another aspect to consider is the economic one, since a bridge represents a much larger investment than the construction of a viaduct.

Viaducts are generally several bridges connected by arched structures . They are usually built over natural or structural elements. Unlike bridges, viaducts are supported by arches made of reinforced concrete or, thousands of years ago, of stone.

A bridge and a viaduct are structurally similar, meaning they share the same design and construction method. Their main difference lies in their length and the surface on which they are built.

In short, both structures are longitudinal with a flat, smooth surface used as a transportation route for vehicles or people . Viaducts, which can be underground or elevated, span the distance between two points. Bridges, on the other hand, are shorter structures that connect two points, but not necessarily reach final destinations.

Bridges and viaducts in Spain

In this final section, we'll discuss the various bridges and viaducts found throughout Spain . Some of the structures on the following list are well worth a visit to admire their grandeur.

New Bridge – Malaga

The most emblematic monument of Ronda , which has its origins in the year 1759.

Los Tilos Viaduct – La Palma

Construction with a total length of 155 meters , which crosses a ravine and in which it can be observed that there are no intermediate supports.

Biscay Bridge

It is a unique bridge, which connects the city of Getxo with Portugalete by crossing the Nervión River.

Montabliz Viaduct

In this case, this structure was built to span the Bisueña River , south of Santander. It has a total length of 721 meters and a height of 150 meters.

Roman Bridge of Cangas de Onís – Asturias

One of the most visited and photographed bridges in Asturias , and even in Spain. This bridge crosses the Sella River in the Asturian municipality of Cangas de Onís.

Lindin Viaduct

With a length of 757 meters and a height reaching 103 meters, it is built over the Abidueiras stream valley.

Triana Bridge – Seville

There are several bridges that cross the Guadalquivir River through the city of Seville, but many say that none compare to the Triana Bridge.

Erques Viaduct

The Erques ravine separated the municipalities of Adeje and Guía de Isora ; over this phenomenon, in 2015, the Erque viaduct was built, which connects the two points directly.

As we have been able to discover, there are slight differences between the two constructions, but not in terms of their structure, as the same type of work is being done. Both structures serve to bridge the gap between two points. They differ in their size.

We hope you find this post interesting and that it answers any questions you may have about what each of these structures consists of and their differences.