Beam - The beam type is the simplest type of bridge. The beam bridge could be anything as simple as a plank of wood to a complex structure. It is made of two or more supports which hold up a beam.
Arch - In the arch type of bridge, weight is carried outward along two paths, curving toward the ground.
Suspension/Cable-stayed - The deck (trafficway) of a suspension bridge is hung by cables which hang from towers. The cables transfer the weight to the towers, which transfer the weight to the ground.
Cable-stayed bridges have towers, but cables from the towers go directly to the road deck, instead of spanning from tower to tower.
Cantilever - In the cantilever type of bridge, two beams support another beam, which is where the deck or trafficway is. The two beams must be anchored, and this must be done well.
-----------------------------------------------------------------------------------------------------------------------------
!BRIDGE TYPES!
There are five different basic types of bridges:
Beam Bridge
The "Beam Bridge" is a good design when trying to span a short gap that is also not very high. It is supported on either end by land or tall columns. If a beam bridge must be longer, support columns can be used to maintain support throughout the span. Materials used are usually concrete and steel.
Truss Bridge
The "Truss Bridge" is similar to a beam bridge except much stronger. These bridges use a pattern of geometrical shapes (triangles) called trusses. These trusses are very rigid (they don't move when pushed) and, thus, make the bridge very STONG! Because of their strength, truss bridges are often used for railway bridges as they must be able to support the great mass and the vibrations of the trains.
Arch Bridge
The "Arch Bridge" is quite economical (cheap) to build. It can span a very deep chasm and maintain support