the bridge It is a structure with a key engineering purpose: to allow the crossing of obstacles such as rivers, valleys, or other infrastructure. This engineering work has evolved significantly since Roman times, becoming a symbol of both technological advancement and utility for everyday life.
Definition and types of bridges
A bridge is defined as a structure that allows transit over an obstacle, whether it be water, land, or any other barrier. They can be used by pedestrians, vehicles, or trains. We can classify bridges into several types:
- Arch bridges: They support their weight by means of an arch, distributing the forces to the sides.
- Hanging bridges: Supported by cables hanging from sturdy towers, allowing for large spans.
- Cable-stayed bridges: Similar to pendants, but with cables connected directly to the pylons by means of braces.
- Girder bridges: They consist of a horizontal beam supported at its ends.
What is a viaduct?
A viaduct is a structure similar to a bridge, but it is notable for its considerable length and the presence of multiple spans or arches that support its structure. The term comes from the Latin via (path) and ductus (driving), marking its main function: connecting long distances over difficult terrain such as valleys or densely built-up cities. In this way, a viaduct can be made up of several short bridges in its length.
Viaducts are built to solve geographical challenges, such as crossing deep valleys or complex urban areas. They allow the movement of trains, cars or pedestrians across several points that are difficult to cross with a single bridge.
Key differences between a bridge and a viaduct
Although the terms "bridge" and "viaduct" are often used interchangeably, There are key differences between both structures:
- Size and length: A bridge is used to cross a single obstacle or barrier, while a viaduct is made up of multiple spans that span large distances.
- Structure: A viaduct is generally composed of several arches or spans, while bridges can be simple single-span structures.
- Geographic function: A bridge is built over a specific obstacle such as a river, while a viaduct can span multiple valleys, rivers, roads, and other obstacles in its path.
Materials and design in construction
The choice of materials for the construction of bridges and viaducts is essential to ensure their stability and durability. Throughout history, a wide range of materials has been used:
- Stone: Used primarily in ancient times, stone offers durability but limits the size of bridges.
- Iron and Steel: 19th and 20th century bridges, such as railway bridges, were based on these strong and flexible materials.
- Reinforced concrete: Nowadays, concrete is the main construction material, as it allows for larger and more complex structures.
The most outstanding bridges and viaducts in the world
There are outstanding examples that illustrate the magnitude and diversity of these projects:
- Danyang-Kunshan Bridge: The longest bridge in the world, with a length of 164 km, considered a viaduct due to its length and multiple spans in China.
- Millau Viaduct: Located in France, it is the highest bridge in the world, with a height of 343 meters, a true marvel of modern engineering.
- Vasco de Gama Bridge: In Portugal, it is the longest bridge in Europe, measuring 17 kilometres.
Maintenance and safety of bridges and viaducts
The safety of large infrastructure depends on strict maintenance. Both bridges and viaducts require periodic assessments to ensure their structural integrity. During these reviews, the following areas are inspected:
- Superstructure: Beams and platforms are checked for cracks, corrosion or damage to connecting elements.
- Substructure: Foundations or supports, especially in above-water structures, where divers inspect submerged foundations.
Proper maintenance ensures that structures withstand both natural wear and tear and the impact of events such as earthquakes, storms or other adverse weather conditions.
Thus, both bridges and viaducts are essential for the development of transport networks on a global level. Knowing their characteristics, differences and maintenance needs is key for any civil engineering project.