As the name implies, a bridge is a type of structure that is built to connect two or sometimes more than two landmasses. The height and size of a bridge depend on the physical obstacle that it needs to overcome. Bridges create an uninterrupted land connection between places that are separated by mountains, valleys, rivers, large expressways and sometimes even seas.
With the help of advanced engineering capabilities and modern-day technology, we can now construct many different types of bridges. The structure and design of a bridge is basically planned according to its usage, which ultimately enhances its functionality and longevity.
In this blog, we are going to learn more about the most common types of bridges in the world and their unique infrastructural characteristics that differentiate them.
So, without further ado, let’s get started!
The 7 Most Common Types of Bridges and Their Uses
The most popular types of bridges and flyovers have been listed and discussed as under:
- Arch Bridge
- Tied Arch Bridge
- Beam Bridge
- Suspension Bridge
- Cable-Stayed Bridge
- Cantilever Bridge
- Truss Bridge
Built by the Romans over 3000 years ago, arch bridges are the oldest types of bridges. If you take a look at the urban landscape of Aosta Valley in Italy, you would see these ancient arch bridges that were built only using stones. Pont-Saint-Martin bridge is one of the best examples in this regard.
The load and weight of the structure is equally redirected towards the centre of the bridge with the help of an arch. This part of the structure has a central stone, which is also known as a key stone. This intelligent design of the bridge holds it up and keeps it from toppling over.
The flexibility of the arch bridge is maintained by installing hinges at each side of the structure as well as at its centre. This allows the bridge to bear the expansion and contraction of its building materials.
Tied Arch Bridge
Unlike an arch bridge, a tied arch bridge is a structure that is based on an overhead arch. It is basically a combination of the infrastructural characteristics of suspension bridges and arch bridges. The horizontal thrust from both ends of the bridge keeps the structure upright by supporting the central arch.
The tension on the vertical cables is balanced by the compression of the arch, managing the load and keeping the bridge stable. Arch bridges are normally used to connect river banks or any two landmasses separated by water.
Ayub Bridge, which is also known as Ayub Arch, is an amazing real-life example of a tied-arch bridge in Pakistan. Completed and launched in 1962 by the then Prime Minister of Pakistan Ayub Khan, the bridge is more than 50 years old. It has a gigantic structure with a total height and length of 806 feet and 207 feet, respectively.
A beam bridge probably has the simplest structure, which is building it is very cheap. It is usually divided into different sections that are supported by crossbeams. The beams of these types of bridges are connected with abutments at each end for structural support and strength.
The longer the bridge, the stronger should be its load-bearing capacity. This is why piers or stanchions are used as additional supports that are installed at different points of the structure. In beam bridges, the force is pushed inwards onto these additional support points and the tension is pulled outward towards both ends of the structure, keeping it from tumbling downward.
Beam bridges are very common in Pakistan. In fact, they are among the most regular features of the infrastructure found in the country’s major cities like Lahore, Karachi and Islamabad. Flyovers that are built all-around Karachi, including the infrastructure of the Green Line Metrobus, are based on these simple bridges.
Uniquely designed and structured, suspension bridges are among the most recognizable types of bridges, especially in the western world. Completed in 1937, Golden Gate Bridge in San Francisco, USA, is an iconic structure, which attracts millions of visitors each year. Standing at a height of around 746 feet and stretching over a mile, it is one of the world’s tallest and largest suspension bridges.
Suspension bridges have tall vertical pillars that keep them stabilized. The structure main cables, as well as small suspenders, are also attached to these pylons. These are the main parts of the structure that support it using the principles of tension. The entire structure of a suspension bridge relies on this force.
With a few pillars or towers, suspension bridges literally hang and sway in the air, which gives them flexibility. You can easily feel vibrations caused by vehicular movement and strong forces of winds while standing on a suspension bridge. This mechanical resonance is very crucial for their structural strength and stability.
As the name implies, a cable-stayed bridge is just a variation of a suspension bridge. It has a similar design and structural characteristics. However, unlike suspension bridges, there are no main vertical cables supporting the structure, just small suspenders that are connected to the top of its host tower. The stability of the bridge is enhanced by these vertical suspenders that rely on the force of tension to keep the deck of the structure upright and stable.
Interesting Fact: New York’s very famous Brooklyn Bridge, which was completed and opened in 1883 is a hybrid. This means that it has the infrastructural characteristics of both suspension and cable-stayed bridges.
The bridges that are built using the cantilever construction techniques are known as cantilever bridges. They have a structure based on pillars that are anchored vertically into the solid ground beneath them. These pillars are used to provide support and strength to a horizontal deck of the bridge that extends in either one or both directions, depending on the structural requirements of the project.
The Quebec Bridge in Canada is a great real-life example of a cantilever bridge. Extending 1,800 feet, it is even the longest cantilever bridge in the world The bridge was completed and opened in 1919.
Due to the unique design of a cantilever bridge, the structural load is distributed evenly both above and below the structure. This extraordinary load management quality keeps the bridge upright. Moreover, cantilever bridges have structural features that are quite similar to truss bridges.
Made with small sections fitted together, bridge trusses are small structural beams that transfer the load from the deck of a bridge to the abutments and piers that support it. This mechanism helps the structure to withstand the tension and other types of forces, adding to the strength and flexibility of a truss bridge.
These are the oldest types of bridges, which were made with wood and iron before the infrastructural application of steel. One great real-life example of a truss bridge is found in Kansas, USA. Cottonwood River Pratt Truss Bridge is an age-old structure, which was built in 1916.
The construction of truss bridges was pretty common in the beginning of the 19th century. However, the design of these bridges was fairly expensive and large amounts of construction materials were needed to materialize it, which used to be either wood, iron or steel. This is why it is not considered a sustainable type of infrastructure in today’s world.
In Pakistan, Lansdowne Bridge, which is located right next to Ayub Arch in Sukkur, Sindh, is one of the most prominent examples of a hybrid structure. Spanning the River Indus and stretching for around 790 feet, it has been equipped with structural features of both cantilever and truss bridges. Lansdowne Bridge was completed in 1889 and has been playing an important part in connecting railway routes in the region for more than a century.
These were some of the most important types of bridges and their real-life examples. We hope you found this post interesting and informative. If you have any questions or feedback, we are always just an email away. So, feel free to reach out to us at email@example.com.
On a side note, if you want to learn about the design and structural mechanics of some of the tallest and most prominent skyscrapers in the world, read this blog.
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