There are many different types of bridges around the world connecting masses of land that would otherwise be separated by water. There are many factors to consider when choosing the right type of bridge to use. Each type has its advantages. Some designs are better suited for a short bridge, while others allow a bridge to stretch for thousands of feet. There are four basic bridge types.
The Arch Bridge
The arch shape allows this bridge to support itself without the use of beams or piers. Some bridges are composed of one large arch or multiple small arches. Arch bridges are typically used for pedestrians, railways and vehicles. This type of bridge requires a very sturdy foundation.The arch bridge is one of the oldest types of bridges.
-- Can span up to 800 feet
-- Natural support system
-- Can cope with bending forces
-- Can be constructed with simple materials
The Beam Bridge
This bridge is the simplest kind of bridge. It is composed of horizontal beams that are supported by strong, closely placed piers. Longer bridges need more piers, and the closer the piers are to each other, the stronger the bridge will be. A simple bridge, like a wooden board over a short river, does not require any piers. Its design is derived from the simple log bridge.
-- Good for short distance
-- Relatively cheap to construct
The Suspension Bridge
Suspension bridges are suspended from cables that are anchored at each end of the bridge. This type of bridge is typically used when a large distance needs to be covered. The flexibility of these bridges prevent them from breaking under the pressure of weight and heavy wind. Early suspension bridges were made of rope or vine.
-- Can span 2,000 to 7,000 feet (longest of any type)
-- Transfers force to its ends
-- Can be built high enough to allow boats to pass under them
The Truss Bridge
The truss bridge is built with many small, straight, steel bars used to support heavy weights. These bars often are fixed into small triangles to create a strong support base. This bridge was popular and common from the 1870s to the 1930s.
-- Simple design
-- Small size
-- Can be constructed with few materials
-- Fairly light