Using the National Bridge Inventory rating scale (established by the FHWA), bridge inspectors rate these structural elements for each bridge:

Deck: The portion of the bridge that directly carries traffic.

Superstructure: The portion of the bridge that supports the deck and connects one substructure element to another.

Substructure: The portion of the bridge that supports the superstructure and distributes all bridge loads to below-ground bridge footings.

Culvert: (Not pictured.) A pipe or small structure used for drainage under a road, railroad or other embankment. A culvert with a span length greater than 20 feet is included in the National Bridge Inventory and receives a rating using the NBI scale.

Structural elements of a typical highway bridge