Search Results - H (181 entries)

H Point: The mechanically hinged hip point of a manikin which simulates the actual pivot center of the human torso and thigh, described in Society of Automotive Engineers (SAE) Recommended Practice J826, "Manikins for Use in Defining Vehicle Seating Accommodations," November 1962.  (49CFR571)

HAA: Height Above Airport  (FAA4)

HACS: Hazard Assessment Computer System  (BTS7)

HAL: Height Above Landing  (FAA4)

Hand Operated Switch: A non-interlocked switch which can only be operated manually.  (49CFR236)

Handling: Physically moving cargo between point-of-rest and any place on the terminal facility, other than the end of ship's tackle.  (MARAD1)

Handoff: A Controller action taken to transfer the radar identification of an aircraft from one Controller to another if the aircraft will enter the receiving Controller's airspace and radio communications with the aircraft will be transferred.  (FAA4)   (FAA8)

Handy Line: Small line used to throw between separated barges or boat and shore, (i.e., heaving line).  (TNDOT1)

HAR: Highway Advisory Radio  (FHWA15)

Harbor: See also Port.

Harbor: An area of water where ships, planes, or other watercraft can anchor or dock.  (DOI4)

Harbor Line: See Permit Line.

Harbor Master: An officer who attends to the berthing, etc., of ships in a harbor.  (MARAD2)

Harmonized System of Codes: An international goods classification system for describing cargo in international trade under a single commodity coding scheme. This code is a hierarchically structured product nomenclature containing approximately 5,000 headings and subheadings.  (MARAD2)

HARS: High Altitude Route System  (FAA17)

HAT: Height Above Touchdown  (FAA4)

Haulage Cost: Cost of loading ore at a mine site and transporting it to a processing plant.  (DOE5)

Hauling Post Holes: Driving an empty truck or trailer.  (ATA1)

Have Numbers: Used by pilots to inform Air Traffic Control (ATC) that they have received runway, wind, and altimeter information only.  (FAA4)

Hawser: A tow line.  (TNDOT1)

Hazard to Navigation: For the purpose of 49CFR195, a pipeline where the top of the pipe is less than 12 inches below the seabed in water less than 15 feet deep, as measured from the mean low water.  (49CFR195)

Hazard Warning Signal: Lamps that flash simultaneously to the front and rear, on both the right and left sides of a commercial motor vehicle, to indicate to an approaching driver the presence of a vehicular hazard.  (49CFR393)

Hazard Zone: One of four levels of hazard (Hazard Zones A through D) assigned to gases, as specified in 49 CFR 173.116(a), and one of two levels of hazards (Hazard Zones A and B) assigned to liquids that are poisonous by inhalation, as specified in 49 CFR 173.133(a) of this subchapter. A hazard zone is based on the LC50 value for acute inhalation toxicity of gases and vapors, as specified in 49 CFR 173.133(a).  (49CFR171)

Hazard Zone: An area identified as a danger to maritime navigation.  (DOI3)

Hazardous Area Reporting Service: Flight monitoring for Visual Flight Rules (VFR) aircraft crossing large bodies of water, swamps, and mountains. This service is provided for the purpose of expeditiously alerting Search and Rescue (SAR) facilities when required. Radio contacts are desired at least every 10 minutes. If contact is lost for more than 15 minutes, SAR will be alerted.  (FAA8)

Hazardous Goods: The categories of hazardous goods carried by inland waterways are those defined by the European Provisions concerning the International Carriage of Dangerous Goods by Inland Waterways.  (TNDOT1)

Hazardous Inflight Weather Advisory Service (HIWAS): Continuous recorded hazardous inflight weather forecasts broadcasted to airborne pilots over selected very high frequency omnidirectional (VOR) outlets defined as an HIWAS BROADCAST AREA.  (FAA4)

Hazardous Liquid: Liquefied Natural Gas (LNG) or a liquid that is flammable or toxic.  (49CFR193)

Hazardous Liquid: Petroleum, petroleum products, or anhydrous ammonia.  (49CFR195)

Hazardous Material (HAZMAT): (See also Highly Volatile Liquid, Marine Pollutant) A substance or material which has been determined by the Secretary of Transportation to be capable of posing an unreasonable risk to health, safety, and property when transported in commerce, and which has been so designated. The term includes hazardous substances, hazardous wastes, marine pollutants, and elevated temperature materials as defined in this section, materials designated as hazardous under the provisions of 49 CFR 172.101 and 172.102, and materials that meet the defining criteria for hazard classes and divisions in 49 CFR 173.  (49CFR171)   (49CFR390)

Hazardous Material (HAZMAT) Employee: A person who is employed by a HAZMAT employer and who in the course of employment directly affects hazardous materials transportation safety. This term includes an owner-operator of a motor vehicle which transports hazardous materials in commerce. This term includes an individual, including a self-employed individual, employed by a HAZMAT employer who, during the course of employment: 1) Loads, unloads, or handles hazardous materials; 2) Tests, reconditions, repairs, modifies, marks, or otherwise represents containers, drums, or packagings as qualified for use in the transportation of hazardous materials; 3) Prepares hazardous materials for transportation; 4) Is responsible for safety of transporting hazardous materials; or 5) Operates a vehicle used to transport hazardous materials.  (49CFR171)

Hazardous Material (HAZMAT) Employer: A person who uses one or more of its employees in connection with: transporting hazardous materials in commerce; causing hazardous materials to be transported or shipped in commerce; or representing, marking, certifying, selling, offering, reconditioning, testing, repairing, or modifying containers, drums, or packagings as qualified for use in the transportation of hazardous materials. This term includes an owner-operator of a motor vehicle which transports hazardous materials in commerce. This term also includes any department, agency, or instrumentality of the United States, a State, a political subdivision of a State, or an Indian tribe engaged in an activity described in the first sentence of this definition.  (49CFR171)

Hazardous Material Residue: The hazardous material remaining in a packaging, including a tank car, after its contents have been unloaded to the maximum extent practicable and before the packaging is either refilled or cleaned of hazardous material and purged to remove any hazardous vapors.  (FRA2)

Hazardous Materials: Any toxic substance, explosive, corrosive material, combustible material, poison, or radioactive material that poses a risk to the public's health, safety, or property when transported in commerce.  (FRA3)

Hazardous Substance: A material, and its mixtures or solutions, that 1) Is identified in the appendix to 49 CFR 172.101; 2) Is in a quantity, in one package, which equals or exceeds the reportable quantity (RQ) listed in the Appendix A to 49 CFR 172.101; and 3) When in a mixture or solution which, for radionuclides, conforms to paragraph 6 of Appendix A, or, for other than radionuclides, is in a concentration by weight which equals or exceeds the concentration corresponding to the RQ of the material, as shown in the Table appearing in 49 CFR 171.8. This definition does not apply to petroleum products that are lubricants or fuels.  (49CFR171)

Hazardous Substance: A material, and its mixtures or solutions, that is identified in the appendix to 49 CFR 172.101, List of Hazardous Substances and Reportable Quantities, of this title when offered for transportation in one package, or in one transport vehicle if not packaged, and when the quantity of the material therein equals or exceeds the reportable quantity (RQ). This definition does not apply to petroleum products that are lubricants or fuels, or to mixtures or solutions of hazardous substances if in a concentration less than that shown in the table in 49 CFR 171.8 of this title, based on the RQ specified for the materials listed in the appendix to 49 CFR 172.101.  (49CFR390)

Hazardous Waste: Any material that is subject to the hazardous waste manifest requirements of the Environmental Protection Agency (EPA) specified in 40 CFR 262 or would be subject to these requirements absent an interim authorization to a State under 40 CFR 123, subpart F.  (49CFR171)   (49CFR390)

HAZMAT: Hazardous Materials  (MARAD2)   (RSPA2)

HBRRP: Highway Bridge Replacement & Rehabilitation Program  (TXDOT)

HC: Hydrocarbon  (DOE6)

HCM: Highway Capacity Manual  (FHWA8)

HDDV: Heavy Duty Diesel Vehicle  (VDOT)

Head: 1) The product of the water's weight and a usable difference in elevation gives a measurement of the potential energy possessed by water. 2) Marine restroom facility.  (DOE5)

Head Impact Area: All nonglazed surfaces of the interior of a vehicle that are statically contactable by a 6.5-inch diameter spherical head form of a measuring device having a pivot point to "top-of-head" dimension infinitely adjustable from 29 to 33 inches in accordance with the procedure explained in 49 CFR 390.5.  (49CFR571)

Head Lamps: Lamps used to provide general illumination ahead of a motor vehicle.  (49CFR393)

Head Log: The heavily reinforced section at each end of the barges and at the bow of the towboat to take the pressure of pushing the entire tow.  (TNDOT1)

Head of Bend: The top or upstream beginning of a bend.  (TNDOT1)

Head of Navigation: The furthest (upriver) location on a river deep enough for navigation.  (TNDOT1)

Head of Passes: A point near the mouth of the Mississippi River where the three principal distributary passes diverge. It is the point from which river distances are measured.  (TNDOT1)

Head On Collision: 1) Refers to a collision where the front end of one vehicle collides with the front-end of another vehicle while the two vehicles are traveling in opposite directions. 2) A collision in which the trains or locomotives involved are traveling in opposite directions on the same track.  (FRA2)   (NHTSA3)

Head On Landing: Landing in which the bow of the boat only is made fast.  (TNDOT1)

Headache Rack: Heavy bulkhead that extends over cab from trailers, usually made of pipe and used in steel hauling.  (ATA1)

Header Bar: Rear cross piece on open top trailer.  (ATA1)

Header Board: Protective shield at front end of flat bottom trailer to prevent freight from shifting forward.  (ATA1)

Headline: Mooring line used in combination to hold a fleet or barge "in".  (TNDOT1)

Headwaters: The upper part of a river system, denoting the upper basin and source streams of a river.  (DOI4)

Headway: The time interval between transit revenue vehicles passing a specified location.  (FTA1)

Heater: Any device or assembly of devices or appliances used to heat the interior of any motor vehicle. This includes a catalytic heater which must meet the requirements of 49 CFR 177.834(1) when flammable liquid or gas is transported.  (49CFR393)

Heavy Duty Truck: Truck with a gross vehicle weight generally in excess of 19,500 pounds (class 6-8). Other minimum weights are used by various law or government agencies.  (ATA2)

Heavy Hauler Trailer: A trailer with one or more of the following characteristics: 1) Its brake lines are designed to adapt to separation or extension of the vehicle frame; or 2) Its body consists only of a platform whose primary cargo carrying surface is not more than 40 inches above the ground in an unloaded condition, except that it may include sides that are designed to be easily removable and a permanent "front-end structure" as that term is used in 49 CFR 393.106.  (49CFR393)

Heavy Lifts: Freight too heavy to be handled by regular ship's tackle.  (TNDOT1)

Heavy Rail: An electric railway with the capacity for a "heavy volume" of traffic and characterized by exclusive rights-of-way, multi-car trains, high speed and rapid acceleration, sophisticated signaling, and high platform loading.  (APTA1)

Heavy Rail: High-speed, passenger rail cars operating singly or in trains of two or more cars on fixed rails in separate rights-of-way from which all other vehicular and foot traffic is excluded.  (FTA1)

Heavy Rail (Rapid Rail): Transit service using rail cars powered by electricity which is usually drawn from a third rail and usually operated on exclusive rights-of-way. It generally uses longer trains and has longer spacing between stations than light rail.  (FTA2)

Heavy Rail Passenger Cars: Rail cars with motive capability, driven by electric power taken from overhead lines or third rails, configured for passenger traffic and usually operated on exclusive right-of-way.  (FTA1)

Height Above Airport: (See also Minimum Descent Altitude) The height of the Minimum Descent Altitude above the published airport elevation. This is published in conjunction with circling minimums.  (FAA4)

Height Above Landing (HAL): The height above a designated helicopter landing area used for helicopter instrument approach procedures.  (FAA4)

Height Above Touchdown (HAT): The height of the Decision Height or Minimum Descent Altitude above the highest runway elevation in the touchdown zone (first 3,000 feet of the runway). Height Above Touchdown (HAT) is published on instrument approach charts in conjunction with all straight in minimums.  (FAA4)

Height/Decision Altitude: A specified altitude or height (A/H) in the precision approach at which a missed approach must be initiated if the required visual reference to continue the approach has not been established. Note 1: Decision altitude is referenced to mean sea level and decision height is referenced to the threshold elevation. Note 2: The required visual reference means that section of the visual aids or of the approach area which should have been in view for sufficient time for the pilot to have made an assessment of the aircraft position and rate of change of position, in relation to the desired flight path.  (FAA4)

Helicopter: See also Gyroplane.

Helicopter: A rotorcraft that, for its horizontal motion, depends principally on its engine-driven rotors.  (14CFR1)

Helicopter: A rotary-wing aircraft which depends principally for its support and motion in the air upon the lift generated by one or more power-driven rotors, rotating on substantially vertical axes. A helicopter is a V/STOL.  (AIA1)

Helicopter: A heavier than air aircraft supported in flight chiefly by the reactions of the air on one or more power driven rotors on substantially vertical axes.  (FAA4)

Helipad: A small, designated area, usually with a prepared surface, on a heliport, airport, landing/takeoff area, apron/ramp, or movement area used for takeoff, landing, or parking of helicopters.  (FAA4)

Heliport: (See also Aerodrome, Aircraft Facility, Airport) 1) An area of land, water, or structure used or intended to be used for the landing and takeoff of helicopters and includes its buildings and facilities if any. 2) An area, either at ground level or elevated on a structure, that is used for the landing and take-off of helicopters and includes some or all of the various facilities useful to helicopter operations such as: helicopter parking, hangar, waiting room, fueling, and maintenance equipment.  (AIA1)   (FAA2)   (FAA4)

Helistop: A minimum facility heliport, either at ground level or elevated on a structure for the landing and takeoff of helicopters, but without such auxiliary facilities as: waiting room, hangar parking, etc.  (AIA1)

HELO: Helicopter  (MTMC1)

HELP: Heavy Vehicle Electronic License Plate  (MTMC1)

HEMTT: Heavy Expanded Mobility Tactical Truck  (MTMC1)

Here She Comes: Term used when another boat appears around a bend.  (TNDOT1)

Hermetically Sealed: Closed by fusion, gasketing, crimping, or equivalent means so that no gas or vapor can enter or escape.  (49CFR171)

HERS: Highway Economic Requirements System  (FHWA12)

Hertz: The standard radio equivalent of frequency in cycles per second of an electromagnetic wave. Kilohertz (kHz) is a frequency of one thousand cycles per second. Megahertz (mHz) is a frequency of one million cycles per second.  (FAA4)

HET: Heavy Equipment Transporter  (MTMC1)

HF: High Frequency  (FAA4)   (FAA17)   (FAA7)   (FAA19)

High Frequency: The frequency band between 3 and 30 mHz.  (FAA4)

High Frequency Communications: High radio frequencies (HF) between 3 and 30 mHz used for air-to-ground voice communication in overseas operations.  (FAA4)

High Occupancy Vehicle (HOV): Vehicles that can carry two or more persons. Examples of high occupancy vehicles are a bus, vanpool, and carpool.  (APTA1)

High Occupancy Vehicle (HOV) Lane: Exclusive road or traffic lane limited to buses, vanpools, carpools, and emergency vehicles.  (APTA1)

High Speed Rail: A rail service having the characteristics of intercity rail service which operates primarily on a dedicated guideway or track not used, for the most part, by freight, including, but not limited to, trains on welded rail, magnetically levitated (MAGLEV) vehicles on a special guideway, or other advanced technology vehicles, designed to travel at speeds in excess of those possible on other types of railroads.  (49CFR37)

High Speed Rail: A rail transportation system with exclusive right-of-way which serves densely traveled corridors at speeds of 124 miles per hour and greater.  (APTA1)

High Speed Taxiway: A long radius taxiway designed and provided with lighting or marking to define the path of aircraft, traveling at high speed (up to 60 knots), from the runway center to a point on the center of a taxiway. Also referred to as long radius exit or turn-off taxiway. The high speed taxiway is designed to expedite aircraft turning off the runway after landing, thus reducing runway occupancy time.  (FAA4)

High Type Road Surface: High flexible, composite, rigid, etc. (Surface/Pavement Type Codes 61, 62, 71-76 and 80).  (FHWA2)

High Volume Area: An area which an oil pipeline having a nominal outside diameter of 20 inches or more crosses a major river or other navigable waters, which, because of the velocity of the river flow and vessel traffic on the river, would require a more rapid response in case of a worst case discharge or substantial threat of such a discharge.  (49CFR194)

High Water Buoy: Small unlighted buoy permanently secured to the end of dikes, lock walls, bear traps, and other river front structures such as mooring cells for the purpose of marking them during high water when they are submerged.  (TNDOT1)

High Water Station: The location to which lights or buoys are moved when river is at or near flood stage, the purpose being 1) To guide navigation in the high water and 2) To locate the light in a position of security against loss.  (TNDOT1)

High-Mileage Households: Households with estimated aggregate annual vehicle mileage that exceeds 12,500 miles.  (DOE4)   (DOE5)

Highly Volatile Liquid: (See also Hazardous Material) A hazardous liquid which will form a vapor cloud when released to the atmosphere and which has a vapor pressure exceeding 276 kPa (40 psia) at 37.8 C (100 F).  (49CFR195)

Highway: See also Arterial, Expressway, Freeway, Freeways and Expressways, Interstate Highway (Freeway or Expressway), Interstate Highway System, Local Streets and Roads, Road.

Highway: Is any road, street, parkway, or freeway/expressway that includes rights-of-way, bridges, railroad-highway crossings, tunnels, drainage structures, signs, guardrail, and protective structures in connection with highways. The highway further includes that portion of any interstate or international bridge or tunnel and the approaches thereto (23 U.S.C. 101a).  (FHWA2)

Highway Capacity Manual: A publication of the Institute of Transportation Engineers defining level of service criteria to determine peak hour traffic congestion.  (FTA1)

Highway Construction Project: A project financed in whole or in part with Federal-aid or Federal funds for the construction, reconstruction or improvement of a highway or portions thereof, including bridges and tunnels.  (23CFR652)

Highway Mode: Consists of public roads and streets, automobiles, vans, trucks, motorcycles, and buses (except local transit buses) operated by transportation companies, other businesses, governments, and households, garages, truck terminals, and other facilities for motor vehicles.  (BTS1)   (BTS2)

Highway Performance Monitoring System (HPMS): The State/Federal system used by the FHWA to provide information on the extent and physical condition of the nation's highway system, its use, performance, and needs. The system includes an inventory of the nation's highways including traffic volumes.  (23CFR500)

Highway Research Information Service (HRIS): A computer-based information storage and retrieval system developed by the Transportation Research Board with financial support from the state highway and transportation departments and the Federal Highway Administration. It consists of summaries of research projects in progress and abstracts of published works.  (TRB1)

Highway Trust Fund: The federal account established by law to hold receipts collected by the government and earmarked for highway programs and a portion of the federal mass transit program. It is supported by the federal gasoline tax and other user taxes.  (TRB1)

Highway User Fee or Tax: A charge levied on persons or organizations based on the use of public roads. Funds collected are usually applied toward highway construction, reconstruction and maintenance. Examples include vehicle registration fees, fuel taxes, and weight-distance taxes.  (ATA2)

Highway-Rail Crossing: (See also At Grade, Grade Crossings) A location where one or more railroad tracks intersect a public or private thoroughfare, a sidewalk, or a pathway.  (FRA3)

Highway-Rail Crossing Accident/Incident: An impact between on track railroad equipment and a highway user (e.g., an automobile, bus, truck, motorcycle, bicycle, farm vehicle, pedestrian or other highway user) at a designated crossing site. Sidewalks, pathways, shoulders and ditches associated with the crossing are considered to be part of the crossing site. The term "highway user" includes pedestrians, cyclists, and all other modes of surface transportation.  (FRA2)

HIN: Hull Identification Number  (USCG1)

HIRL: High Intensity Runway Lights  (FAA16)   (FAA17)

Hit and Run: (See also Crash) A hit-and-run occurs when a motor vehicle in transport, or its driver, departs from the scene after being involved in a crash prior to police arrival on the scene. Fleeing pedestrians and motor vehicles not in transport are excluded from the definition. It does not matter whether the hit-and-run vehicle was striking or struck.  (NHTSA1)

HIWAS: Hazardous Inflight Weather Advisory Service  (FAA4)   (FAA8)

HM: Hazardous Materials  (FHWA10)   (RSPA1)

HMAC: Hazardous Materials Advisory Council  (RSPA1)

HMIS: Hazardous Materials Information System  (RSPA1)

HMMWV: High - Mobility Multipurpose Wheeled Vehicle  (MTMC1)

HMR: Hazardous Materials Regulations  (RSPA1)

HMS: Hazardous Materials Safety  (RSPA1)

HMTA: Hazardous Materials Transportation Act  (RSPA1)

HMTUSA: Hazardous Materials Transportation Uniform Safety Act of 1990  (FHWA10)   (RSPA1)

HND: Highways for National Defense  (MTMC1)

HNL: Honolulu International Airport  (FAA11)

HNM: Helicopter Noise Model  (OST3)

Hobo: Tractor that is shifted from terminal to terminal.  (ATA1)

Hold For Release: Used by Air Traffic Control (ATC) to delay an aircraft for traffic management reasons; i.e., weather, traffic volume, etc. Hold for release instructions (including departure delay information) are used to inform a pilot or a controller (either directly or through an authorized relay) that an Instrument Flight Rules (IFR) departure clearance is not valid until a release time or additional instructions have been received.  (FAA4)

Hold Open: To hold below or above an object (i.e., wide of the mark) being steered on, depending on direction. Upstream tows normally hold above, downstream tows below, the object.  (TNDOT1)

Holding Agency: A federal agency having accountability for motor vehicles owned by the Government. This term applies when a federal agency has authority to take possession of, assign or reassign motor vehicles regardless of which agency is using the motor vehicles.  (GSA2)

Holding Mark: An object, usually an aid to navigation, on which the pilot of a tow will steer.  (TNDOT1)

Holding On: Steering steadily on a mark or object.  (TNDOT1)

Home Base: The location where a vehicle is usually parked when not in use or on the road.  (BOC4)

Home Signal: A roadway signal at the entrance to a route or block to govern trains in entering and using that route or block.  (49CFR236)

Homing: The procedure of using the direction finding equipment of one radio station with the emission of another radio station, where at least one of the stations is mobile, and whereby the mobile station proceeds continuously towards the other station.  (FAA4)

Hood Lifter: Garage mechanic.  (ATA1)

Hopper: A top loading, funnel-shaped structure for temporary storage of loose materials, which will be dispensed from the bottom.  (DOI4)

Hopper Barge: An open-compartment barge used for dry bulk cargo that does not require protection from the weather.  (TNDOT1)

Hopper Body: Truck body capable of discharging its load through a bottom opening without tilting.  (ATA1)

Horse: Tractor or power unit.  (ATA1)

Horse Light: Spotlight mounted on cab to reveal open-range livestock.  (ATA1)

Horse Van Body: Truck designed for the transportation of valuable horses (livestock).  (ATA1)

Horsepower (HP): The amount of work that an engine can perform within a given time. One horsepower equals 33,000 foot pounds of work per minute.  (GSA2)

Hot Load: Rush shipment of cargo.  (ATA1)

Hot-Deck Imputation: A statistical procedure for deriving a probable response to a questionnaire item concerning a household or vehicle, where no response was given during the survey. To perform the procedure, the households or vehicles are sorted by variables related to the missing item. Thus, a series of "sort categories" are formed, which are internally homogeneous with respect to the sort variables. Within each category, households or vehicles for which the questionnaire item is not missing are randomly selected to serve as "donors" to supply values for the missing item of "recipient" households or vehicles.  (DOE4)

HOU: William P Hobby Airport  (FAA11)

Household: A group of persons whose usual place of residence is a specific housing unit; these persons may or may not be related to each other. The total of all U.S. households represents the total civilian non-institutionalized population. Does not include group quarters (i.e., 10 or more persons living together, none of whom are related).  (FHWA3)

Household Trip: One or more household members traveling together.  (FHWA3)

Household Vehicle: A motorized vehicle that is owned, leased, rented or company owned and available to be used regularly by household members during the travel period. Includes vehicles used solely for business purposes or business owned vehicles if kept at home and used for the home to work trip, (e.g., taxicabs, police cars, etc.) which may be owned by, or assigned to, household members for their regular use. Includes all vehicles that were owned or available for use by members of the household during the travel period even though a vehicle may have been sold before the interview. Excludes vehicles that were not working and not expected to be working within 60 days, and vehicles that were purchased or received after the designated travel day.  (FHWA3)

Housing Unit: A house, apartment, a group of rooms, or a single room occupied or intended for occupancy as separate living quarters. Separate living quarters are those in which the occupants do not live and eat with any other persons in the structure and which have either 1) direct access from the outside of the building or through a common hallway intended to be used by the occupants of another unit or by the general public, or 2) complete kitchen facilities for the exclusive use of the occupants. The occupants may be a single family, one person living alone, two or more families living together, or any other group of related or unrelated persons who share living arrangements.  (DOE6)

HOV: High Occupancy Vehicle  (BTS2)

Hover Check: Used to describe when a helicopter/ Vertical Takeoff and Landing (VTOL) aircraft requires a stabilized hover to conduct a performance/power check prior to hover taxi, air taxi, or takeoff. Altitude of the hover will vary based on the purpose of the check.  (FAA4)

Hover Taxi: Used to describe a helicopter/Vertical Takeoff and Landing (VTOL) aircraft movement conducted above the surface and in ground effect at airspeeds less than approximately 20 knots. The actual height may vary, and some helicopters may require hover taxi above 26 feet above ground level (AGL) to reduce ground effect turbulence or provide clearance for cargo slingloads.  (FAA4)

How Do You Hear Me?: A question relating to the quality of the transmission or to determine how well the transmission is being received.  (FAA4)

HP: Horsepower  (AGA1)

HP&R: Highway Planning and Research  (MTMC1)

HPMS: Highway Performance Monitoring System  (BTS2)   (FHWA8)

HQ: Headquarters

HRIS: Highway Research Information Service  (TRB1)

HRPT: Highway Regulating Point Team  (MTMC1)

HS: Harmonized System  (BTS2)

HSAC: Helicopter Safety Advisory Conference  (OST3)

HSCT: High Speed Commercial Transport  (MTMC1)

HSGT: High-Speed Ground Transportation  (TRB1)

HSI: Horizontal Situation Indicators  (FAA6)

HSIS: Highway Safety Information System  (FHWA7)

HSR: High Speed Rail  (OST3)

HSR/MLA: High Speed Rail/Maglev Association  (ENO1)

HSSGT: High-Speed Guided Ground Transportation  (TXDOT)

HTA: Heavier Than Air  (Aircraft)   (MTMC1)

HTP: Highway Traffic Point  (MTMC1)

HUD: Heads-Up Display  (FAA17)

HUFSAM: Highway Users Federation for Safety and Mobility  (FHWA15)

Hull Inspector: Colloquial river term for any large piece of drift or submerged piling, log, rock etc.  (TNDOT1)

Human Factor: (See also Employee Human Factor) Behavior affecting elements of railroad employee job performance.  (FRA3)

Humping: The process of connecting a moving rail car with a motionless rail car within a rail classification yard in order to make up a train. The cars move by gravity from an incline or "hump" onto the appropriate track.  (MARAD2)

Hurdle: (See also Dike) A colloquial term for a dike.  (TNDOT1)

HVL: Highly Volatile Liquid  (49CFR195)

Hydraulic Head: The distance between the respective elevations of the upstream water surface (headwater) above and the downstream surface water (tailwater) below a hydroelectric power plant.  (DOE5)

Hydrocarbon: A compound that contains only hydrogen and carbon. The simplest and lightest forms of hydrocarbon are gaseous. With greater molecular weights, they are liquid, while the heaviest are solids.  (DOE6)

Hyphenated Point: Basically two or more neighboring communities which, in terms of authorization shown in a carrier's Certificate of Public Convenience and Necessity, are treated as a single community.  (FAA15)

HYSIM: Highway Driving Simulator  (MM)

HZ: Hertz  (FAA4)