A truss bridge is the strongest kind of bridge. It combines materials in a simple and efficient way that reduces and spreads out loads over a large area. They flex less than other kinds of bridges and provide greater stability even in extreme weather or traffic.
Truss bridges have a basic design that couples repeated triangular conglomeration so as to create a matrix of support structures. These beams are pinned in place rather than affixed rigidly so as to allow vibrations to pass through the interconnected triangles and spread the force evenly through the design. This helps increase stability and reduce flexing when high winds or heavy traffic are present on the bridge.
The stability and strength of the truss bridge make it ideal for repeated use by heavy loads. It is the most common design seen in train trestles and bridges. This design is also prominent in commuter bridges and in areas where wide spans need to be traversed.
Truss bridges are commonly constructed using steel though traditional models are also made with wood. They are easy to design and engineer, making them economical to execute in the field. This fact coupled with the durability of the design makes it popular for financial and infrastructure reasons.