Developing a Guide for On-Bridge Stormwater Treatment Practices (2024)
Chapter: Glossary of Key Terms
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Suggested Citation:
"Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Developing a Guide for On-Bridge Stormwater Treatment Practices. Washington, DC: The National Academies Press.
doi: 10.17226/27905.
Glossary of Key Terms
| Common Parts of a Bridge | |
| Abutments | The substructure elements at either end of a bridge where the bridge connects to land. A multi-part bridge may have abutments at intermediate points where the bridge connects to land. |
| Beam | A general term for an approximately horizontal structural element that supports the bridge deck. Girders and cross beams are common types of beams in a bridge design. Note that due to the unique geometries of bridges, it is rare for elements to be truly horizontal. In this report, horizontal refers to a general direction, not a perfect horizontal plane. |
| Bent cap | A horizontal member that spans the bents and serves as the support for the girders. |
| Bents (also known as piers) | A vertical part of the substructure located between the ends of a bridge. They are typically made up of two or more columns connected at their topmost ends by a cap. |
| Cross beam | A horizontal structural element that typically runs between girders to support the bridge deck. These are often parallel or angled relative to the direction of the roadway. |
| Deck | The structural platform that spans the girders and cross beams and serves as the surface of the bridge. The deck is a structural element. This includes the travel lanes and the shoulders and can also include sidewalks or multi-use paths. |
| Deck drains | Openings that pass through the bridge deck to convey stormwater runoff. |
| Edge barrier | A general term used to refer to the barrier(s) at the outer edges of the bridge that help prevent vehicles or pedestrians from going over the sides. This is distinct from a center barrier which separates opposing traffic between two sides of a bridge. |
| Girders | A horizontal structural element that runs between piers or bents in the direction of the roadway. A girder is a type of beam. |
| Guard rail | A simple open type of edge barrier. |
| Lower strand | Refers to the lower edge of the girders. |
| Parapet (also known as solid barrier) | A railing system made of reinforced concrete along the outside edge of a bridge deck used to help protect vehicles and pedestrians. |
| Piers (also known as bents) | A type of bent that consists of a single column. |
| Side drains | Openings that pass through the edge barrier of the bridge to convey stormwater runoff. |
| Span | Refers to lengths of bridge between substructure elements. Span is also used to refer to specific elements, such as the “center span” of a bridge. |
| Substructure | A general term referring to the piers and abutments that lie between the bridge foundation and the superstructure. |
Suggested Citation:
"Glossary of Key Terms." National Academies of Sciences, Engineering, and Medicine. 2024. Developing a Guide for On-Bridge Stormwater Treatment Practices. Washington, DC: The National Academies Press.
doi: 10.17226/27905.
| Superstructure | A general term referring to the girders, beams, deck, shoulders, edge barriers, towers (if applicable) other supporting elements above the substructure that support the riding surface of the bridge. |
| Related Design and O&M Terms | |
| Base flood elevation | Refers to the 100-year peak water surface elevation defined by the Federal Emergency Management Agency (FEMA). |
| Clogging lifespan | The time that a media filter can operate at or above its design infiltration rate between rehabilitation or media replacement events. |
| Constructability | Refers to the relative complexity and cost required to construct a design. |
| Drainage criteria (also known as storm drainage) | A general term referring to the requirements for draining stormwater from a bridge during storms for the purpose of vehicular safety. Drainage criteria typically include the return interval storm event, the allowable lateral spread, and/or other criteria to define the size and spacing of drainage elements. |
| Floodplain | The floodway and the floodplain fringe that is inundated in the 100-year base flood event. |
| Floodway | The channel and adjacent overbank areas necessary to effectively convey floodwaters. |
| Maintenance interval | The time interval at which maintenance activities are required to allow for the ongoing function of a BMP. This includes both routine and rehabilitative maintenance. For a media filtration BMP, this may include sediment removal, debris removal, media replacement, or other activities. |
| Manual labor | Refers to hand labor, such as the use of shovels, raking of or replacing media, carrying of bags, or other similar activities. |
| O&M | Operations and maintenance, including inspection, routine maintenance, and major/rehabilitative maintenance. |
| Structural risks | Refers to the potential for a BMP design to compromise the structural integrity of a bridge. |
| Traditional hoist | Refers to a truck-mounted boom lift system that can extend over the side of a bridge and lift vertically. |
| Under-bridge inspection equipment | Refers to a type of lift, boom, or platform truck designed to allow work below the bridge deck via a truck parked on the bridge surface. For example, equipment that allows inspection personnel to ride in a bucket or walk on a temporary walkway below the bridge. |
| Vacuum truck | A truck with an extendable hose attached to a boom that is designed to pick up and transfer liquids, slurries, and loose aggregates into a tank mounted on the truck. |
| Vertical clearance | A general term used to refer to the vertical separation between the bottom of the bridge beams and the maximum height that is needed to safely pass vehicles (ships/boats/trains/trucks, etc.) below the bridge. This could be driven by the base flood elevation, navigability requirements, or rail/traffic requirements. |
| Water quality flows | The flow rate generated from a regulatory water quality treatment event, such as the flow generated from the 85th percentile storm event or the flow required to treat a certain percentage of long-term runoff volume. Water quality flows are nearly always smaller than the storm flows relevant for drainage criteria. |
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