The construction of roads and railway lines over bodies of water would be impossible without the use of bridges. Bridges are defined using various categories: structure, fixed or movable, use, and material used.
Bridges by structure
• Arch bridges – These kinds of bridges have arches which are located and serve as the primary structure for supporting the bridge. Depending on the maximum amount of the load which will be used on the road and stress forces, one or more hinges are incorporated.
• Beam bridges – Several beams of different sizes and shapes are used to support this basic type of bridge. The beams used can either be V-shaped or inclined depending on the preference of the architect.
• Truss bridges – The use of diagonal meshes of posts on top make these bridges the most common. The most famous designs are the use of single vertical posts which support two diagonal supporters at the centre (King posts) and two vertical posts connected at the top by two vertical posts, two diagonal posts and a horizontal post (queen posts).
• Cantilever – The load is supported on this bridge by the use of diagonal bracing, unlike in arch bridges which use vertical bracing. Truss formation is used both above and below the bridge.
• Tied arch bridges- They are similar to arch bridges but transfer the load passing over them and that of their structure to top cords which are connected to the bottom cords of the bridge.
• Suspension bridges – Cables or ropes from vertical suspenders are used to hold the weight of traffic and that of the bridge
• Cable-stayed bridges – Deck cables which are connected directly to one or more columns are used support the bridge.
Fixed of movable types
A majority of the bridges used today are set and have no movable parts. There are, however, movable bridges which are electrically controlled.
Types by use
Bridges can be categorised based on their use. Some of the primary classifications are car traffic, double-decked, pedestrian, train bridges, viaducts, pipelines, and commercial bridges.
Types by materials
The kind of material used for construction is another category that can be used to define various types of buildings. Different materials are used depending on the load which will be passing over the bridge. The commonly used materials used in constructing buildings are natural materials, stone, wood, advanced materials, concrete, and steel. Many bridges, however, combine more than one material in their construction.