There's no doubt you've seen a bridge, and it's almost as likely that you've traveled over one. If you've ever laid a plank or log down over a stream to keep from getting wet, you've even constructed a bridge. Bridges are truly ubiquitous -- a natural part of everyday life. A bridge provides passage over some sort of obstacle: a river, a valley, a road, a set of railroad tracks...
In this article, we will look at the three major types of bridges so that you can understand how each one works. The type of bridge used depends on various features of the obstacle. The main feature that controls the bridge type is the size of the obstacle. How far is it from one side to the other? This is a major factor in determining what type of bridge to use, and by the time you are done reading this article you will understand why.
