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WTC Construction Lingo
World Trade Center Construction Commonly Used Terms
Anchors/Rock Anchors: Rock anchors resist forces by means of corrosion protected steel bars embedded into bedrock. Geotechnical structures need anchors to counteract the uplift and other forces acting on foundations. The threaded bar is bonded to the bedrock socket wall or virgin soil by using high-strength grout (cement mixture). After the anchors are constructed, the free-lengths are then post-tensioned, but bolts are grouted the full length of the bar and cannot be post-tensioned. Rock anchors and bolts can have very high load capacities.
Asphalt Wearing Course: A layer of asphalt, generally three inches thick that sits on top of the concrete base, providing a smooth surface on which vehicles ride.
Backfill: The dirt and sand used to fill in a street around underground utilities and below the concrete base.
Barnes Dance: The timing of traffic signals at an intersection to give pedestrians "Walk" signals in every direction; an example is currently in place at the intersection of Broadway, Park Row, Vesey, and Ann Streets.
Bathtub: The sub-grade basement of the main World Trade Center site (divided into east and west sides), whose slurry walls withhold groundwater from the site.
Bent: A set of columns connected by beams in a direction transverse to the flow of traffic (A). For example, in NYCT Subway Structures (1 Line Subway Box) there are steel subway "bents" typically every five feet along the tunnel.
Bollard: A short post set in the sidewalk or roadway to block vehicles from entering an area; typically used for security purposes.
Building Line: The edge of a building, excluding the sidewalk (see usage under "capital street reconstruction").
Buttress Slab: The concrete slab on which a buttress is installed. A buttress is an architectural structure built against (a counterfort) or projecting from a wall which serves to support or reinforce the wall. Buttresses are fairly common on more ancient buildings as a means of providing support to act against the lateral (sideways) forces arising out of the roof structures that lack adequate bracing. In more modern buildings, better internal bracing of structures arising out of a more well-developed understanding of structural engineering diminishes the use of buttresses; however they are by no means obsolete, and will continue to be found as integral parts of certain structures, not least in certain designs of free standing curtain walls and retaining walls.
Caisson: A watertight chamber used to install the foundation of a structure.
Capital Street Reconstruction: The reconstruction of all components of a street from building line to building line, including the asphalt wearing course, concrete base, curbs and sidewalks; generally involves repair, replacement, and relocation of utilities.
Cased to Rock: A term used to describe the attachment or sleeving process where (pipe, steel rebar, steel beams) are placed into rock and grouted to provide support and/or act as a structural element.
Catch Basin: An underground receptacle with a surface grating for street drainage that connects to the sewer system.
Cattle Chute: A temporary, protected lane for vehicular traffic.
Cobrahead: A standard-issue, stainless-steel street light, 25 to 30 feet in height; the name refers to the lamp at the end of the pole (whose shape resembles the head of a cobra), though generally it includes the pole and arm as well.
Concrete Base: A layer of concrete six to nine inches thick underneath the asphalt; the concrete base bears the weight of the vehicles on the road.
Core Drilling: A cylindrical sample of earth mineral or rock extracted from the ground by means of a coring device so that the strata are undisturbed in the sample. Core drilling is also used in boring as in coring through a cement slab floor for sample collection or other sub-structural investigation. Core drills are used for many applications, either where the core needs to be preserved (the drilling apparatus used in obtaining a core sample is often referred to as a corer), or where drilling can be done more rapidly since much less material needs to be removed than with a standard bit. This is the reason that diamond-tipped core drills are commonly used in construction to create holes for pipes, manholes, and other large-diameter penetrations in concrete or stone.
Counterfort: Counterfort walls are cantilever walls strengthened with the back of the wall slab and base slab. The counterforts act as tension stiffeners and connect the wall slab and the base to reduce the bending and shearing stresses.
Curtain Wall: The exterior wall or façade of a building which does not bear any of the building's load.
Delta Barrier: A retractable barrier installed within a street to prevent or allow access; manufactured by Delta Scientific Corp. (seen around the New York Stock Exchange and Civic Center areas).
Duct: A small pipe through which electrical, telecommunications, and other smaller underground utility lines run; also known as a "conduit".
Egress: The motion of exiting; i.e., "There are many pedestrians on Church Street due to high-volume egress from the PATH station."
Engineered Resurfacing: The process of removing the asphalt wearing course from a street surface, examining the concrete base below for damage, making all necessary repairs, and laying a new asphalt wearing course.
Egress: The motion of exiting; i.e., "There are many pedestrians on Church Street due to high-volume egress from the PATH station."
French Barrier: A fence-like, freestanding metal barricade, generally used for directing pedestrians.
Grade: Surface elevation; i.e., "The subway is below grade."
Guide Walls: Concrete guide walls are constructed in a shallow trench so that the deep vertical trenches for larger wall structures/foundations may be excavated. After the formwork for the guide walls has been erected and the concrete placed, the cavities outside the guide walls are filled with earth and timber shores are wedged between the walls.
Hilfiker Retaining Wall: Reinforced soil retaining walls [commonly grouped as Mechanically Stabilized Embankments -MSE] that behave as gravity structures in an integral unit and provide structural flexibility. Welded wire mats placed within layers of compacted backfill provide the necessary lateral support.
House Connection: The secondary distribution and collection pipes for non-wired utilities, such as gas, steam, water, and sewer that connect a structure to the mains.
Infrastructure: The system of public utilities.
Jersey Barrier: A solid-concrete, freestanding barricade; typically eight feet.
Jet Grout: Jet grouting is a general term describing various construction techniques in which ultra high-pressure fluids or binders are injected into the soil at high velocities (800 to 1,000 feet per second). Jet grouting breaks up the soil structure completely and mixes the soil particles in-situ with a binder to create a homogeneous mass, which in time solidifies.
Jumbo Steel: Refers to the physically large members of structural steel used in steel frame erection.
Leading Pedestrian Interval (LPI): The timing of a "Walk" signal to allow pedestrians extra time to cross before the vehicular traffic signal turns green; currently in place along Church Street as part of the city's Street Management Project.
Liner Wall: A concrete liner wall, often two to three feet thick, is constructed along the face of an existing wall to protect and reinforce that wall. For example, a liner wall will extend north from the southwest corner of the West Bathtub continuing along and west of the Central Chiller Plant.
Long light-emiting diode (LED): A semiconductor diode that emits light and has an extremely long life span (typically 10 years), commonly used in electronic displays including citywide traffic signals.
Main: The primary distribution and collection pipes for non-wired utilities, such as gas, steam, water, and sewer; typically 12 to 20 inches in diameter
Maintenance and Protection of Traffic (MPT) Plan: A plan for the various signs, markings, devices, and detours that are required to allow traffic, both vehicular and pedestrian, through a construction site.
Milling and Resurfacing: The process of removing the asphalt wearing course using a machine that "mills" and disposes of the material and then laying a new asphalt wearing course.
Mud Slab: A base slab of low-strength concrete from 2" to 6" thick placed over a wet sub-base before placing a concrete footing or grade slab.
Oculus: A circular opening at the top of a rounded structure (seen in World Trade Center Transportation Hub and Fulton Street Transit Center designs).
Parapet Wall: A low protective wall or railing along the edge of a raised platform, bridge, or roof; may be straight, stepped, curved, solid, or with decorative openings
Particulate: Fine road and construction dust, diesel soot, and other visible and microscopic particles that are suspended in the air, typically a result of emissions from fossil-fuel burning, vehicles, and boilers.
Pilaster: A shallow rectangular feature projecting from a wall, having a capital and base and usually imitating the form of a column.
Planter: A more decorative piece of "street furniture" used in place of bollards and barricades; typically filled with flowers and greenery.
Plate: A sheet of steel used to cover construction trenches and pits to allow traffic to flow when construction is not happening.
Platoon: The group of cars that collect and move through a traffic signal together.
Ponding: The collection of water at a low point of a paved surface.
Pontoon: Wooden beams laid side by side over street construction sites to open lanes of traffic.
Post-Tensioning: A method of reinforcing concrete, masonry, and other structural elements. Post-Tensioning is a method of prestressing. Prestressed concrete or masonry has internal stresses (forces) induced into it during the construction phase for the purpose of counteracting the anticipated external loads that it will encounter during its lifecycle.
Repointing: The process of removing deteriorated mortar from the joints of a masonry wall and replacing it with new mortar.
Secant Piles/Walls: Secant pile walls are an innovative way to build retaining walls. They are formed by a series of interlocking drilled shafts and are used primarily where there is a high water table or unsuitable ground conditions. Secant pile walls are attractive near buildings, roads, and other sensitive structures because of the lack of noise and vibration during construction. Secant walls can be used to form a continuous watertight wall - an added benefit on environmental projects.
Shear Walls: In structural engineering, a shear wall is a wall composed of braced panels (also known as shear panels) to counter the effects of lateral loads acting on a structure. Wind and earthquake loads are the most common loads braced wall lines are designed to counteract. Under several building codes, including the International Building Code (where it is called a braced wall line) and Uniform Building Code, all exterior wall lines in wood or steel frame construction must be braced. Depending on the size of the building some interior walls must be braced as well.
Sheep Run: A temporary, protected pedestrian walkway.
Shoring: A general term used in construction to describe the process of supporting a structure in order to prevent collapse so that construction can proceed. The phrase can also be used as a noun to refer to the materials used in the process.
Sidewalk Shed: A structure built over the sidewalk and around the exterior of a building, while work is occurring on the building, to protect pedestrians from falling debris; also called a "sidewalk bridge"
Slalom: A zigzag course created by barricades.
Slurry Wall: The three-foot-thick concrete perimeter wall that forms the World Trade Center site's east and west bathtubs, supported laterally by high-strength tieback anchors
Steam Flange: The joint connecting two steam mains.
Superstructure: The part of a building or structure above the foundations.
Test Pit: A patch of roadway opened to inspect underground utilities to identify potential conflicts between existing and proposed structures
Temporary Certificate of Occupancy (TCO): A legal document that allows for a building's temporary occupancy, pending final inspection.
Tieback: A horizontal wire used to reinforce retaining walls for stability. With one end of the tieback secured to the wall, the other end is anchored to a stable structure, such as a concrete deadman which has been driven into the ground. The tieback-deadman structure resists forces that would otherwise cause the wall to lean, as for example, when a seawall is pushed seaward by water trapped on the landward side after a heavy rain.
Timber Curb: Temporary, movable curbs made of painted wood, sometimes heightened to form upright barricades.
Traffic Enforcement Agent (TEA): A uniformed member of the NYPD who directs vehicular traffic, or engages in summons enforcement.
Trench: A long cut in the ground, used commonly for water-main replacement and installation in place of capital street reconstructions
Trumpets: To provide lateral support of a wall as excavation proceeds downward, tieback anchors are installed through sleeves ("trumpets") in a slurry wall, drilled through the soil using steel pipe casing, and then drilled 30 to 35 feet into bedrock. Each anchor is grouted in place, tested, and locked off.
Ultra-Low-Sulfur Diesel (ULSD): A "clean diesel" fuel that reduces emissions of nitrogen oxides and particulate matter; one of the cleanest fuels available (New York City and State laws now require that non-road construction equipment used on city construction projects and by public agencies use ULSD.)
Vault: An open space beneath a sidewalk or street and usually attached to a building's basement, sometimes used for utilities or storage space.
Source: LowerManhattan.info / Port Authority of New York & New Jersey