The earliest bridge consisted of a log over a stream. Today's bridges are technological wonders. Bridges no longer go over just streams.
Bridges can be parts of super highways.
They can stretch across wide areas of water. They connect islands. Engineers have many things to consider when planning a bridge. They must consider what the purpose of the structure is, what the dead and live loads will be, the environment, and structural hazards such as wind and earthquakes. Despite all of the advances and new technology that have allowed us to build larger bridges, there remains four basic types of bridge structures.