There are three basic types of draw bridge. The most common is the kind where one or both sides rise to a near vertical position allowing a tall ship to pass.

Sometimes a section of the bridge is on a turntable so that it can rotate 90 degrees allowing ships to pass on both sides.

Another type of drawbridge is the vertical lift where a section between two towers rises high enough to allow ships to pass underneath. The Tower Bridge in London is one of those.

Without draw bridges, Hollywood car chases would be a lot less interesting.
Howard