View of Morrison Bridge from SW.

Bridges come in many shapes and sizes.  When you consider the types of construction materials used, the style of construction and the main use of the crossing, you find that bridges can take many varied forms.  Bridges can be simple wooden beams over small streams or massive steel and concrete suspension structures crossing miles of open water and shipping channels.  The purpose of this page is to familiarize you with some of the basic bridge types and provide examples of each that you can see in the Portland, OR metropolitan area.

Bridges are of two general types: fixed and movable. Fixed bridges are usually classified by their basic geometry such as arches, trusses, beams, girder, suspension and cable stayed.  Movable bridges are more complex structures having machinery for opening a portion of the bridge, allowing the passage of ships or other traffic through the bridge.  Movable bridges are usually constructed at sites where there is not sufficient room or clearance for the construction of a larger structure.  Types of movable bridges include vertical lift, swing and bascule.