Federal-Aid Highway Program Guidance on High Occupancy Vehicle (HOV) Lanes
August 2008
Glossary of Terms
Alternate fuel vehicle - A vehicle that is operating on (1) methanol, denatured ethanol, or other alcohol; (2) a mixture containing at least 85 percent of methanol, denatured ethanol, and other alcohols by volume with gasoline or other fuel; (3) natural gas; (4) liquefied petroleum gas; (5) hydrogen; (6) coal derived liquid fuels; (7) fuels (except alcohol) derived from solar energy; or (8) any other fuel that the Secretary prescribes by regulation that is not substantially petroleum and that would yield substantial energy security and environmental benefits, including fuels regulated under 10 CFR 490.
High Occupancy Vehicle (HOV) - A motor vehicle, carrying at least two or more persons, including carpools, vanpools, and buses.
HOT lane - "High Occupancy/Toll" lane means any HOV lane that allows vehicles not meeting minimum occupancy requirement to use the lane by paying a toll.
HOV facility - Any kind of facility that gives priority treatment to buses, vanpools, carpools and high-occupancy vehicles, including HOV lanes, park-and-ride lots, and other support facilities or elements.
HOV lane - Any preferential lane designated for exclusive use by vehicles with 2 or more occupants for all or part of a day, including a designated lane on a freeway, other highway or a street, or independent roadway on a separate right-of-way.
HOV system - Any coordinated region wide network of integrated HOV facilities.
Inherently Low Emission Vehicles (ILEV) - Any kind of vehicle which, because of the inherent properties of the fuel system design will not have significant evaporative emissions, even if its evaporative emission control system has failed. These vehicles are certified by the Environmental Protection Agency pursuant to 40 CFR 88.311-93 and labeled pursuant to 40 CFR 88.312.93.
Low Emission & Energy-Efficient Vehicles - A vehicle that has been certified as meeting the Tier II emission level under section 202(i) of the Clean Air Act for that make and model year and is certified by EPA to have achieved not less than a 50-percent increase in city fuel economy or not less than a 25 percent increase in combined city-highway fuel economy relative to a comparable vehicle that is an internal combustion gasoline fueled vehicle; or is an alternative fuel vehicle.
Occupancy requirement - Any restriction that regulates the use of a facility for any period of the day based on a specified number of persons in a vehicle.
Public transportation vehicle - A vehicle that that (1) provides designated public transportation as defined in Section 221 of the Americans with Disabilities Act of 1990 or provides public school transportation (i.e. to and from public or private primary, secondary, or tertiary schools); and (2) is owned or operated by a public entity; or is operated under a contract with a public entity; or is operated pursuant to a license by the Secretary or a State agency to provide motorbus or school vehicle transportation services to the public.
Single Occupancy Vehicle (SOV) - Any motor vehicle not meeting the established occupancy requirement of a HOV lane. While it is possible for a vehicle with more than one occupant to not meet the occupancy requirement if the standard is established at more than two persons, the term SOV is used to encompass all such vehicles not meeting the occupancy requirement.
Tier II Emission - The Tier II emission level established in regulations prescribed by the Environmental Protection Agency under section 202(i) of the Clean Air Act for that vehicle's make, model, and model year. The Tier II emission standards are based on a system of emission bins in which light-duty vehicles and light-duty trucks are certified in one of the eight bins; Bin 1 represents the cleanest or lowest emitting vehicles, and Bin 8 represents the highest emitting vehicles of the Tier II bins.
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