There are various types of bridge designs, with each having its own set of strengths and weaknesses, and among these designs having a superstructure with link elements creating triangular units are known as truss bridges. They are among the oldest types of bridges that are found all over the world and are still regarded as state-of-the-art technology. Their linked elements that are normally straight are thought to be designed to be stressed from tension, compression or, most of the time, both aspects to handle to lively loads—in fact, these bridges have a unique ability to take compression and tension more than other bridge designs. Their simple styles have been analyzed since the 19th century.
However, like other major structures, truss bridges have been a subject of debates that discuss whether they are appropriate to construct or not. To build or own opinion about this matter, let us take a look at their pros and cons.
List of Pros of Truss Bridges
1. They are light, but strong.
Most of the time, these bridges effectively use materials needed for their construction, making them very economical to build, while not compromising on their grounds. As they use small timbers or beams of metal, the trusses would be light, but are strong enough to handle loads thanks to the ridged triangles that are an integral component of their designs.
2. Their designs are true and tested.
While truss bridges are among the oldest types of bridges still used in the world today, they are still considered as among those having the best state-of-the-art designs. These structures tend to hold up well for a long time, serving a lot of communities very well.
3. They can be constructed virtually anywhere.
One of the primary reasons that truss bridges have been the preferred structures over other types is their versatility to be constructed in places where construction could be difficult, such as locations needing long span of areas like deep trenches. Aside from this, it does not take much effort to create a suitable environment for these bridges to be properly installed. Even in areas where, initially, it might be impossible to build such a structure, truss bridges can allow for a strong span and can still effectively hold heavy amounts of traffic. In some situations, you will see truss bridges built conveniently to connect over railways and between mountains.
4. They can be built under extreme conditions.
These types of bridges can be built quickly in places where many other types cannot, linking areas that other types will not work in. This is definitely a huge advantage when it comes to using these bridges.
5. They allow placement of roadways on the structure itself.
A truss bridge is the only type of bridge that allows a roadbed to be placed on the structure itself. As it has a deck tress, it allows certain transportation options, such as a rail, to be placed straight across it, offering a stable point for crossing any span.
6. They make good use of materials.
A truss bridge can be built from metal or wood. Because of its design, it makes good use of limited construction materials to achieve strength that far outweighs its cost. Though it uses more of the materials and requires many support rods and poles, these components can be made from different materials, while other types of bridges usually depend only on metal.
List of Cons of Truss Bridges
1. They take up a lot of space.
These bridges need additional amount of space when compared to other types, which means that certain locations might need adjustment of existing structures in order to accommodate these bridges.
2. They require high costs.
While it is said that these bridges’ design efficiently uses materials, it does use a lot of them. Building a truss bridge can be costly, and its upkeep requires time and money. And even if this type of structure is strong, having the capability to support a lot of force, it is not seen to be built anymore these days due to the high costs that come with it. Maintaining a truss bridge can be more complicated and expensive, thus it can be a huge drawback for a community that is having a tight maintenance budget. As many people realized, this bridge may not be the most cost-effective option for their communities.
3. They are quite difficult to maintain.
Because of the amount of materials they use, these types of bridges require a lot of upkeep. While the extra materials provide them with a lot of strength, they would cost a lot of money for the labor to keep them functional. With this in mind, installation and maintenance of these bridges might be unmanageable for certain communities.
4. They require efficient design to really work.
The main purpose of a truss bridge is to have all of its trusses to supports the weight of its span over time, and if its design is not managed properly, there could be some trusses created that have zero-pressure members, which means that they would only look nice, but are not working effectively for the entire structure.
5. They can lead to wasting of materials.
Without the proper design and work practice, constructing a truss bridge can result to waste of materials. As previously mentioned, it could have trusses with zero-pressure members that are doing nothing.
6. They are not always the best option.
Originally, the truss bridge concept was created to be a perfect solution to the many limits in materials and construction. But since then, many truss bridges have been re-evaluated and replaced with more structurally sound and efficient types of bridges.
Truss bridges are incredibly string and durable, so they can be utilized for many years with proper maintenance. While they are considered as ideal in many situations, it is not always the case. By knowing the pros and cons that come with them, you and your community can properly decide if they are the type of bridges that are appropriate to meet your needs.
Natalie Regoli is a child of God, devoted wife, and mother of two boys. She has a Master's Degree in Law from The University of Texas. Natalie has been published in several national journals and has been practicing law for 18 years.