Glossary

Abutment
A retaining wall on opposite sides of a bridge or viaduct that supports the deck beams or girders and tie the structure into the approaching roadway.

Beam
A horizontal structure member supporting the bridge deck and the traffic load, usually smaller than a girder.  Can be pre-stressed concrete or steel.

Column
A vertical, structural element supporting the bridge deck and the traffic load.

Deck
The roadway portion of a bridge, including shoulders, usually composed of reinforced concrete.

Expansion Joint
A meeting point between two parts of a structure that allows for movement due to expansion or contraction caused by temperature changes.  Commonly visible on a bridge deck as a hinged or movable connection.

Federal Highway Administration (FHWA)
An agency within the U.S. Department of Transportation that supports State and local governments in the design, construction, and maintenance of the nation’s highway system (Federal Aid Highway Program) and various federally and tribal owned lands (Federal Lands Highway Program).

Fill
Earth, stone or other material used to raise the ground level, form an embankment or fill the inside of an abutment.

Footing
Part of the substructure or foundation that rests directly on the soil, bedrock or piles.

Formliner
A type of Wall Treatment used to create designs on concrete walls, making them more attractive walls for highways, neighborhoods and parks. Formliners come in many different shapes and designs, and can produce a variety of textures and designs on concrete.

Formwork
A temporary structure that encloses the reinforcing steel (re-bars) and supports freshly placed concrete and allows it to harden into the desired shape.

Functionally Obsolete
A functionally obsolete bridge is one that was built to standards not in use today, such as narrow lane and shoulder widths, inadequate vertical clearance, etc. These bridges are not inherently unsafe.

Girder
A horizontal structure member, larger than a beam, supporting the bridge deck and the traffic load.

Hardscaping
Areas covered by paving blocks, stamped concrete, stone and other durable materials so that the ground is no longer exposed to the elements.

Jersey Barrier
A low, reinforced concrete wall wider at the base, tapering vertically to near mid-height, then continuing straight up to its top. The shape is designed to direct traffic back toward its own lane of travel and prevent crossing of a median or leaving the roadway.

Parapet
A low, reinforced concrete wall along the outside edge of a bridge deck.

Pile
A long steel or wooden column driven deep into the ground to form part of a foundation or substructure.

Pile Driver
A machine that repeatedly drops a heavy weight on top of a pile until the pile reaches solid soil,  rock a point of friction where it cannot be driven further.

Pre-Cast Girder or Beam
A girder or beam fabricated off-site using reinforced concrete and post -tensioning cables that create a slight bend (camber) in the member that straightens out under the deck and traffic load.  They are shipped to the construction site by truck and hoisted into place by cranes.

Reinforced Concrete
Concrete with steel bars (re-bars) or mesh embedded in it for increased strength in tension.

Single Span Structure
A bridge whose superstructure is supported by abutment walls at either end.

Span
The horizontal space between two supports of a structure. Also refers to the structure itself. May be used as a noun or a verb.

Specifications or Specs
A document that explains all material and construction requirements of the bridge structure to be constructed.

Streetscape
A combination of the elements within and along a street and sidewalk that define a street’s appearance, identity and function, including street furniture (benches, trash cans, etc.), landscaping, trees, sidewalks and pavement designs, among others.

Structurally Deficient 
Bridges are considered structurally deficient if significant load carrying elements are found to be in poor condition due to deterioration.  A structurally deficient bridge is not necessarily unsafe. When left open to traffic, these bridges typically require significant maintenance and repair to remain in service.  They are often posted with weight limits to restrict the gross weight of vehicles using them.

Substructure
The substructure consists of all parts that support the superstructure, including footings, pilings, abutments and piers.

Superstructure
The superstructure consists of the components that actually span the bridge crossing, including structural members (girders, beams, etc.), the bridge deck, p
arapets, handrails, sidewalk, lighting and drainage system.

Two-Span Structure
A bridge whose superstructure is supported by a center pier or column and abutment walls at either end. Additional piers or columns would correspondingly increase the number of spans.

Viaduct
An elevated bridge-like structure that carries a road or railroad over lower ground.