| Keyword |
Definition |
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Hazardous Material |
Any toxic substance or explosive, corrosive, combustible, poisonous, or radioactive material that poses a risk to the public's health, safety, or property, particularly when transported in commerce. |
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Heavy Rail (Transit) |
An electric railway with the capacity to transport a heavy volume of passenger traffic and characterized by exclusive rights-of-way, multicar trains, high speed, rapid acceleration, sophisticated signaling, and high-platform loading. Also known as: Subway, Elevated (railway), or Metropolitan railway (metro). |
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High Occupancy Vehicle (HOV)
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Vehicles carrying two or more people. The number that constitutes an HOV for the purposes of HOV highway lanes may be designated differently by different transportation agencies. |
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High Occupancy Vehicle Lane |
Exclusive road or traffic lane limited to buses, vanpools, carpools, and emergency vehicles. (APTA1) |
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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) |
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Highway Bridge Replacement and Rehabilitation Program (HBRRP)
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Established under 23 U.S.C., Section 144, to enable the several states to replace and rehabilitate highway bridges when it is determined that the bridge is unsafe because of structural deficiencies, physical deterioration, or functional obsolescence. |
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Highway Trust Fund (HTF)
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An account established by law to hold Federal highway user taxes that are dedicated for highway and transit related purposes. The HTF has two accounts: the Highway Account, and the Mass Transit Account. |
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Highway-Rail Grade Crossing (Rail) |
A location where one or more railroad tracks are crossed by a public highway, road, street, or a private roadway at grade, including sidewalks and pathways at or associated with the crossing. |
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Highway-User Tax |
A charge levied on persons or organizations based on their use of public roads. Funds collected are usually applied toward highway construction, reconstruction, and maintenance. |
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Historic Preservation |
Protection and treatment of the nation's significant historic buildings, landmarks, landscapes, battlefields, tribal communities, and archeological sites; prominent federally-owned buildings; and State and privately-owned properties. [National Park Service, Historic Preservation Services] |
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Hydrocarbons (HC)
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Colorless gaseous compounds originating from evaporation and the incomplete combustion of fossil fuels. |
