Transportation Conformity Reference Guide
Glossary
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
- 1-Hour ozone NAAQS
- The 1-hour ozone national ambient air quality standard codified at 40 CFR 50.9
8-Hour ozone NAAQS- The 8-hour ozone national ambient air quality standard codified at 40 CFR 50.10
Area source- Small stationary and non-transportation pollution sources that are too small and/or numerous to be included as point sources but may collectively contribute significantly to air pollution (i.e. dry cleaners).
Arterial- A class of roads serving major traffic movements (high-speed, high volume) for travel between major points.
Attainment area- An area considered to have air quality that meets or exceeds the U.S. Environmental Protection Agency (EPA) health standards used in the Clean Air Act. An area may be an attainment area for one pollutant and a nonattainment area for others. Nonattainment areas are areas considered not to have met these standards for designated pollutants.
Clean Air Act- The original Clean Air Act was passed in 1963, but our national air pollution control program is actually based on the 1970 version of the law. The 1990 Clean Air Act Amendments are the most far-reaching revisions of the 1970 law. In this summary, we refer to the 1990 amendments as the 1990 Clean Air Act.
Carbon monoxide (CO)- A colorless, odorless, tasteless gas formed in large part by incomplete combustion of fuel. Human activities (i.e. transportation or industrial processes) are largely the source for CO contamination.
Conformity- Process to assess the compliance of any transportation plan, program, or project with air quality implementation plans. The conformity process is defined by the Clean Air Act.
Congestion Mitigation and Air Quality Improvement (CMAQ) Program- A categorical funding program under the Federal-aid Highway Program. Directs funding to projects that contribute to meeting or maintaining National air quality standards. CMAQ funds generally may not be used for projects that result in the construction of new capacity available to SOVs (single-occupant vehicles).
Congestion Management Process- SAFETEA-LU requires that each Transportation Management Area (see definition of TMA) address congestion management through a process that provides for effective management and operation, based on a cooperatively developed and implemented metropolitan-wide strategy, of new and existing transportation facilities eligible for funding under title 23 and 49 through the use of travel demand reduction and operational management strategies.
Design concept- Type of facility identified by the project, e.g., freeway, expressway, arterial highway, grade-separated highway, reserved right-of-way rail transit, mixed-traffic rail transit, exclusive busway, etc.
Design scope- The design aspects which will affect the proposed facility's impact on regional emissions, usually as they relate to vehicle or person carrying capacity and control, e.g., number of lanes, or tracks to be constructed or added, length of project, signalization, access control including approximate number and location of interchanges, preferential treatment for high-occupancy vehicles, etc.
Donut area- Geographic areas outside a metropolitan planning area boundary, but inside the boundary of a nonattainment or maintenance area that contains any part of a metropolitan area(s). These areas are not isolated rural nonattainment and maintenance areas.
Emissions inventory- A complete list of sources and amounts of pollutant emissions within a specific area and time interval.
Environmental Impact Statement- Report developed as part of the National Environmental Policy Act requirements, which details any adverse economic, social, and environmental effects of a proposed transportation project for which Federal funding is being sought. Adverse effects could include air, water, or noise pollution; destruction or disruption of natural resources; adverse employment effects; injurious displacement of people or businesses; or disruption of desirable community or regional growth.
Environmental Protection Agency (EPA)- EPA is the Federal regulatory agency responsible for administering and the enforcement of Federal environmental laws including the Clean Air Act, the Clean Water Act, the Endangered Species Act, and others.
Federal Highway Administration (FHWA)- An agency of the U.S. Department of Transportation that funds highway planning and programs.
Federal Transit Administration (FTA)- An agency of the U.S. Department of Transportation that funds transit planning and programs.
FHWA/FTA project- For the purposes of transportation conformity, it is any highway or transit project which is proposed to receive funding assistance and approval through the Federal-Aid Highway program or the Federal mass transit program, or requires FHWA or FTA approval for some aspect of the project, such as connection to an interstate highway or deviation from applicable design standards on the interstate system.
Forecast period- With respect to a transportation plan is the period covered by the transportation plan pursuant to 23 CFR Part 450.
Fixed-route- Term applied to transit service that is regularly scheduled and operates over a set route; usually refers to bus service.
Freeway- A divided arterial highway designed for the unimpeded flow of large traffic volumes. Access to a freeway is rigorously controlled and intersection grade separations are required.
High occupancy vehicles (HOVs)- Generally applied to vehicles carrying three or more people; freeways, expressways and other large volume roads may have lanes designated for use by carpools, vanpools, and buses. The term HOV is also sometimes used to refer to high-occupancy vehicle lanes themselves.
Highway- Term applies to roads, streets, and parkways, and also includes rights-of-way, bridges, railroad crossings, tunnels, drainage structures, signs, guard rails, and protective structures in connection with highways.
Highway project- An undertaking to implement or modify a highway facility or highway-related program. Such an undertaking consists of all required phases necessary for implementation.
Hot-spot analysis- An estimation of likely future localized CO and PM10 pollutant concentrations and a comparison of those concentrations to the national ambient air quality standards. Hot-spot analysis assesses impacts on a scale smaller than the entire nonattainment or maintenance area, including, for example, congested roadway intersections and highways or transit terminals, and uses an air quality dispersion model to determine the effects of emissions on air quality.
Hydrocarbons (HC)- Colorless gaseous compounds originating from evaporation and the incomplete combustion of fossil fuels.
Inspection and Maintenance Program (I/M)- An emissions testing and inspection program implemented by States in nonattainment areas to ensure that the catalytic or other emissions control devices on in-use vehicles are properly maintained.
Intermodal- The ability to connect, and connections between modes of transportation.
Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA)- Legislative initiative by the U.S. Congress that restructured funding for transportation programs. ISTEA authorized increased levels of highway and transportation funding from FY92-97 and increased the role of regional planning commissions/MPOs in funding decisions. The Act also required comprehensive regional and Statewide long-term transportation plans and places an increased emphasis on public participation and transportation alternatives.
Interstate Highway System- The system of highways that connects the principal metropolitan areas, cities, and industrial centers of the United States. The Interstate Highway System also connects the U.S. to internationally significant routes in Mexico and Canada.
Isolated rural nonattainment and maintenance areas- Areas that do not contain or are not part of any metropolitan planning area as designed under the transportation planning regulations. Isolated rural areas do not have Federally required metropolitan transportation plans or TIPs and do not have projects that are part of the emissions analysis of any MPO's metropolitan transportation plan or TIP. Projects in such areas are instead included in statewide transportation improvement programs. These areas are not donut areas.
Land use- Refers to the manner in which portions of land or the structures on them are used (i.e. commercial, residential, retail, industrial, etc.).
Lapse- This means that conformity determination for a transportation plan or TIP has expired, and thus there is no currently conforming transportation plan and TIP.
Level of Service (LOS)- This term refers to a standard measurement used by transportation officials which reflects the relative ease of traffic flow on a scale of A to F, with free-flow being rated LOS-A and congested conditions rated as LOS-F.
Local street- A street intended solely for access to adjacent properties.
Long term- In transportation planning, refers to a time span of, generally, 20 years. The transportation plan for metropolitan areas and for States should include projections for land use, population, and employment for the 20-year period.
Maintenance area- Any geographic region of the United States previously designated nonattainment pursuant to the CAA Amendments of 1990 and subsequently redesignated to attainment subject to the requirement to develop a maintenance plan under section 175A of the CAA, as amended.
Metropolitan Planning Area- The geographic area determined by agreement between the metropolitan planning organization for the area and the Governor.
Metropolitan Planning Organization (MPO)- The policy board of an organization created as a result of the designation process of the MPO. MPOs are established by agreement of the Governor and units of general-purpose local government which together represent 75 percent of the affected population of an urbanized area.
Mobile source- Mobile sources include motor vehicles, aircraft, seagoing vessels, and other transportation modes.
Mode- A form of transportation such as an automobile, bus or bicycle.
Motor Vehicle Emissions Budget- is that portion of the total allowable emissions defined in the submitted or approved control strategy implementation plan revision or maintenance plan for a certain date for the purpose of meeting reasonable further progress milestones or demonstrating attainment or maintenance of the NAAQS, for any criteria pollutant or its precursors, allocated to highway and transit vehicle use and emissions.
Multi modal- The availability of transportation options using different modes within a system or corridor.
National Ambient Air Quality Standards (NAAQS)- Federal standards that set allowable concentrations and exposure limits for various pollutants. The EPA developed the standards in response to a requirement of the CAA.
National Environmental Policy Act (NEPA)- Is the National Environmental Policy Act of 1969, as amended (42 U.S.C. 4321 et seq.).
Nonattainment area- Any geographic region of the United States which has been designated as nonattainment under section 107 of the CAA for any pollutant for which a national ambient air quality standard exists.
Oxygenated gasoline- Gasoline enriched with oxygen bearing liquids to reduce CO production by permitting more complete combustion.
Ozone (O3)- Ozone is a colorless gas with a sweet odor. Ozone is not a direct emission from transportation sources. It is a secondary pollutant formed when HC and NOx combine in the presence of sunlight. Ozone is associated with smog or haze conditions. Although the ozone in the upper atmosphere protects us from harmful ultraviolet rays, ground-level ozone produces an unhealthy environment in which to live. Ozone is created by human and natural sources.
Particulate Matter (PM), (PM-10), (PM-2.5)- Any material that exists as solid or liquid in the atmosphere. Particulate matter may be in the form of fly ash, soot, dust, fog, fumes, etc. Small particulate matter is too small to be filtered by the nose and lungs. PM-10, is particulate matter that is less than 10 microns in size. PM-2.5 is particulate matter that is less than 2.5 microns in size. A micron is one millionth of a meter.
Parts per million (ppm)- A measure of air pollutant concentrations.
Project- A highway project or transit project
Public participation- The active and meaningful involvement of the public in the development of transportation plans and programs.
Reformulated gasoline (RFG)- Gasoline specifically developed to reduce undesirable combustion products.
Regionally significant project- A transportation project (other than an exempt project) that is on a facility which serves regional transportation needs (such as access to and from the area outside of the region, major activity centers in the region, major planned developments such as new retail malls, sports complexes, etc., or transportation terminals as well as most terminals themselves) and would normally be included in the modeling of a metropolitan area's transportation network, including at a minimum all principal arterial highways and all fixed guideway transit facilities that offer an alternative to regional highway travel.
Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (SAFETEA-LU)- Enacted August 10, 2005 as Public Law 109-59. SAFETEA-LU authorizes the Federal surface transportation programs for highways and transit for the 5-year period 2005-2009.
State Implementation Plan (SIP)- A plan mandated by the CAA and developed by the State that contains procedures to monitor, control, maintain, and enforce compliance with the NAAQS.
Stationary source- Relatively large, fixed sources of emissions (i.e. chemical process industries, petroleum refining and petrochemical operations, or wood processing).
Transportation Equity Act for the 21st Century (TEA-21)- Enacted June 9, 1998 as Public Law 105-178. TEA-21 authorizes the Federal surface transportation programs for highways, highway safety, and transit for the 6-year period 1998-2003.
Telecommuting- The substitution, either partially or completely, of transportation to a conventional office through the use of computer and telecommunications technologies (e.g. telephones, personal computers, modems, facsimile machines, electronic mail).
Transit- Mass transportation by bus, rail, or other conveyance which provides general or special service to the public on a regular and continuing basis. It does not include school buses or charter or sightseeing services.
Transit project- An undertaking to implement or modify a transit facility or transit-related program; purchase transit vehicles or equipment; or provide financial assistance for transit operations. It does not include actions that are solely within the jurisdiction of local transit agencies, such as changes in routes, schedules, or fares. It may consist of several phases.
Transportation Control Measures (TCMs)- Any measure that is specifically identified and committed to in the applicable implementation plan that is either one of the types listed in section 108 of the CAA, or any other measure for the purpose of reducing emissions or concentrations of air pollutants from transportation sources by reducing vehicle use or changing traffic flow or congestion conditions. Notwithstanding the first sentence of this definition, vehicle technology-based, fuel-based, and maintenance-based measures which control the emissions from vehicles under fixed traffic conditions are not TCMs for the purposes of transportation conformity.
Transportation Improvement Program (TIP)- Also known as a transportation program, a TIP is a program of transportation projects drawn from, or consistent with, the transportation plan and developed pursuant to Title 23, U.S.C. (United States Code) and the Federal Transit Act. This document is prepared by metropolitan planning organizations listing projects to be funded with FHWA/FTA funds for the next one- to three-year period.
Transportation Management Area (TMA )- A Transportation Management Area (TMA) is an area designated by the Secretary of Transportation, having an urbanized area population of over 200,000, or upon special request from the Governor and the MPO designated for the area. Within a TMA, all transportation plans and programs must be based on a continuing and comprehensive planning process carried out by the MPO in cooperation with States and transit operators. The TMA boundary affects the responsibility for the selection of transportation projects that receive Federal funds.
Transportation plan- This is a long-range plan that identifies facilities that should function as an integrated transportation system, and developed pursuant to Title 23, U.S.C. (United States Code) and the Federal Transit Act. It gives emphasis to those facilities that serve important national and regional transportation functions, and includes a financial plan that demonstrates how the long-range plan can be implemented.
U.S. Department of Transportation (DOT)- The principal, direct, Federal funding agency for transportation facilities and programs. Includes the Federal Highway Administration (FHWA), the Federal Transit Administration (FTA), the Federal Railroad Administration (FRA), and others.
Urbanized area- An Urbanized Area is a statistical geographic entity designated by the Census Bureau, consisting of a central core and adjacent densely settled territory that together contain at least 50,000 people, generally with an overall population density of at least 1,000 people per square mile.
Vehicle miles traveled (VMT)- The sum of distances traveled by all motor vehicles in a specified region.
Volatile organic compounds (VOCs)- VOCs come from vehicle exhaust, paint thinners, solvents, and other petroleum-based products. A number of exhaust VOCs are also toxic, with the potential to cause cancer.
Zone- The smallest geographically designated area for analysis of transportation activity. A zone can be from one to ten square miles in area. Average zone size depends on the total size of study area.
