Last Updated on March 16, 2021 by Filip Poutintsev
A Truss bridge is a type of bridge whose main element is a truss, which is a structure of connected elements that form triangular units. Truss bridges are among the oldest types of bridges that are found all over the world and are still regarded as state-of-the-art technology. 
A truss is formed by many different beams that come together to form triangles to support the bridge’s way. Trusses are used to support and stabilize the bridge. A truss is a very rigid structure, and it transfers the load from a single point to a much wider area. It helps to handle compression, tension, and weight of the different types of loads.
The reason why the shape (truss) is so useful for building bridges is the fact that when it is placed under stress, the tension or compression created makes the structure stronger. This process makes it possible to support dynamic loads under variable conditions.
The key benefit of using a truss bridge to span a distance is that they are relatively lightweight, but can still be reinforced to provide strength. Because of the triangular design, each part of the bridge helps to support other parts, making it an effective design.
The basic types of truss bridges are simple in design. The traditions of truss bridges originated from the early 19th century. Truss bridges are considered to be one of the oldest types of bridges and are economic to construct because they use materials efficiently.
While it is very strong and has tremendous load capabilities, there are also several drawbacks associated with the truss bridge design. Let’s take a deep look at the pros and cons associated with truss bridges.
Pros of Truss Bridge
1. High Strength
Truss bridges are characterized by their interconnecting triangular structures, which give them the strength to withstand more heavy and dynamic loads. It gives the ability to carry heavy traffic loads, making it ideal for dense population areas and railroad crossings.
Truss Bridge is a reliable type because of its ability to withstand the weight of heavy loads of the cars and trucks that use it to get to and from a destination.
2. Ease of Construction
More popularity of truss bridge over other types is their versatility to be constructed in places where construction could be difficult, such as locations needing a long span of areas like deep trenches.
Engineers prefer building truss bridges because these structures have the flexibility to be built in different locations with different depths and width. Moreover, they can be built with ease in between mountains and even over railways.
3. Uses Materials Effectively
While the truss bridge has many linked parts to make up its structure—its use of materials is extremely effective. Because of its design, it makes good use of limited construction materials to achieve strength that far outweighs its cost. Materials such as wood, iron, and steel are all utilized to their highest potential, hence reduces building cost.
4. Affordable Design Option
Compared to other bridge designs truss bridge designs often require fewer materials to complete the structure. Minimal amounts of materials needed to build a truss bridge and each piece is used very efficiently. This makes it possible to save on design and implementation costs, while also reducing the labor needs of the structure.
5. No Span Restrictions
One of the most appealing properties of a truss bridge is that it can be built over very long as well as very short distances. Many truss bridges tend to be small, spanning small distances within transportation networks. Engineers can install this type of bridge almost anywhere in the world today because of the efficiency of its design.
6. Road is Placed on the Top of the Span
The truss bridge is one of the only types of bridges that allow for the road to be placed on top of it, rather than built into it. With a truss bridge, the transportation surface is placed on top of the support structures.
That makes it easier to integrate existing construction principles into the bridge while minimizing traffic delays. That’s why truss bridges can be built off-site, then installed once the pieces are delivered. This makes the truss bridge both versatile and economical to build.
Cons of Truss Bridge
1. A Lot of Maintenance is Required
A truss bridge, like any load-bearing structure, will require regular and detailed maintenance. Truss bridges may provide high levels of support, but the additional components and connections of the bridge mean it requires high levels of maintenance as well.
Every inch of the structure plays a significant role in how the span performs. There are several additional connections and components in this design that create a higher risk of failure at some point.
2. Space Consuming
Perhaps one of the drawbacks of building truss bridges is the amount of space it can eat up by the infrastructure. The interconnecting triangular components need to be large in order to bear and distribute heavy loads.
The structure of a truss bridge is large by design, hence can take up quite a bit of space. This means that in certain places, the truss bridge may not be the best option or might need adjustment of existing structures in order to accommodate these bridges.
3. Requires Professional to Built
A truss bridge might seem like a simple design, but it can be quite complex. Each and every piece needs to fit perfectly to perform its function, and anything less will mean that the bridge simply does not hold a load. A truss bridge requires detailed engineering and specialist construction—this does not come cheap.
4. Heavy Weight
Because truss bridges are so large and use a lot of materials, hence the overall weight of the structure can be very heavy. Depending on the landscape supporting the bridge, some reinforcement may be necessary to cope with the weight. If the landscape can’t support a truss bridge then there may be other bridge options such as suspension or beam bridges, which might be more suitable.
5. Have a Lower Weight Tolerance
Truss bridges were first built with lightweight vehicles in mind. Although they can handle appropriate levels of traffic, there are some designs that cannot support certain heavy-duty vehicles. On older truss bridges, some drivers must pay attention to the maximum weight rating to prevent damaging the structure.
6. High Cost
While it is said that truss bridge design efficiently uses materials, it does use a lot of them. Professionals are required to design the structure of the bridge, which aids up its building cost. Building 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.
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