What is a viaduct?

A viaduct is a feat of engineering that connects the end of one road to another over a hollow or valley. Its infrastructure generally consists of a highly resistant surface designed to ensure the passage of a large number of people, either on foot or in vehicles.

The word is derived from two Latin words: via, which means “way,” and ductus, which means “driving.” Their shape is similar to the aqueducts built in ancient Rome, with the arched shape and symmetrical proportion.

The difference between a bridge and a viaduct

The main difference between a bridge and a viaduct is the span. While a bridge ensures passage from one place to another over an obstacle or body of water, viaducts also create paths through various natural features, such as valleys or ravines, and they may even be located over other civil works, such as avenues, streets, and of course, bridges.

Simply put: any viaduct can be considered a bridge, but not all bridges are viaducts. To test this statement out, let’s look at two different structures: Madrid’s Segovia Viaduct and the Centennial Bridge in Santiago, Chile.

The Segovia Viaduct

This viaduct is located at the extension of Calle de Bailén and crosses over Calle de Segovia. Its purpose is to provide safe passage over the ravine located in the city. This civil engineering work connects important points in the city of Madrid, and it’s a reference point for those who live in the area.

It came out of the need to have a way across the San Pedro stream. Though it wasn’t built until the 19th century, the project is known to have existed early as 1730. Finally, construction began in 1870, ending four years later with a structure made of wood and iron. 

The Segovia Viaduct has undergone various renovations throughout its history. The last one took place in 1974 and included construction of a new concrete and granite structure.

Santiago de Chile Viaduct

It is located in the commune of Vitacura, located in the municipality of Santiago; its actual name is Puente Centenario (the Centennial Bridge). It measures 195 meters in all and crosses the Mapocho River. The viaduct is designed for vehicular use and comprises three different highways: the Acceso Nororiente, the Costanera Norte, and the Vespucio Oriente.

Both examples are civil works that share the same fundamental characteristic: withstanding heavy traffic and constant use, in addition to ensuring the safety of those who use them while getting around.

What are the most impressive viaducts in the world?

• The Millau Viaduct, southern France. It’s almost two and a half kilometers long and reaches 343 meters in height. The project started in 1987 and finally opened in 2004. It cost €320 million and, as of 2010, 4.5 million vehicles drove over it each year.
• Vasco da Gama Bridge, in Portugal. This is the second-longest bridge in Europe, measuring 17.3 km long (11.5 km of which is the viaduct). It has spanned the Tagus River since 1998. Building it required 300 families to move.
• Duge Bridge, in China. This is the highest bridge in the world at 565 meters, and it measures 1,340 meters in length. It’s part of the G56 Hangzhou-Ruili Expressway, and it has shortened travel times by about an hour since it opened in 2016.
• Golden Gate Bridge, in the United States. This is one of the most famous viaducts in the world. It was built from 1933 to 1937 in response to the exponential increase in vehicular traffic after World War I.

Fun facts

• The first Segovia Viaduct’s inauguration in 1874 coincided with Pedro Calderón de la Barca’s remains being transferred to the San Nicolás cemetery.
• Due to the high annual suicide rate on the Segovia Viaduct, it is also colloquially known as “the suicide bridge.”
• One of the most important characteristics of the Ormaiztegui viaduct in the Basque Country is that the person in charge of its construction was famous engineer Alexandre Lavalley, Gustave Eiffel’s predecessor.
• The Sankey Valley Viaduct in England was the world’s first railway viaduct.
• The Miguel Alemán viaduct’s current location in Mexico City was once the site of one of the 70 rivers that flowed into Lake Tenochtitlán before the arrival of Hernán Cortéś.