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Access, Accessibility The opportunity to reach a given end use within a certain time frame, or without being impeded by physical, social or economic barriers. Typically, accessibility is the extent to which transportation improvements make connections between geographic areas or portions of the region that were not previously well connected.

Alternative An alternative includes various improvements designed to address transportation deficiencies in the project area.

Americans with Disabilities Act of 1990 (ADA) Federal Law that requires public facilities, including transportation services, to be fully accessible for persons with disabilities.

Arterial An arterial roadway serves major traffic movements or major traffic corridors. While they may provide access to abutting land, their primary function is to serve traffic moving through the region.

Average Daily Traffic (ADT) The total average volume of traffic in both directions on a highway during a 24-hour time period.


Base Year The lead off year of data used in a study, usually the current year or a year with the most recent comprehensive data.

Baseline Network/No Build Network The forecast year transportation network containing only committed projects in the study area, and fiscally constrained long range transportation plan projects outside of the study area.

Build/No Build As defined by the federal transportation legislation, Metropolitan Planning Organizations (MPOs) must demonstrate that “building” or implementing a long range plan (LRP) and Transportation Improvement Program (TlP) will provide more emissions reduction (improve air quality) than by “not building” or not implementing that same long range plan and TIP.


Capacity The maximum amount of traffic on any transportation facility that can be accommodated and still function.

Chicago Metropolitan Agency for Planning (CMAP) Formed in 2005, CMAP integrates planning for land use and transportation in the seven counties (Cook, DuPage, Kane, Kendall, Lake, McHenry, and Will) of northeastern Illinois. The new organization combined the region's two previously separate transportation and land-use planning organizations -- Chicago Area Transportation Study (CATS) and the Northeastern Illinois Planning Commission (NIPC) -- into a single agency.

Conformity The process to assess the compliance of any transportation plan, program, or project with air quality control plans. The conformity process is defined by the Clean Air Act and related amendments.
Congested Vehicle Miles of Travel
This measure indicates how many vehicle miles are traveled over the threshold for congestion conditions. If there is no congestion, then Congested VMT would be zero, however if traffic builds beyond the limit for congestion, then this measure would report the difference, or the amount causing the congestion.

Congestion Management System (CMS) A plan developed by a Transportation Management Area (TMA) that provides for effective management of new and existing transportation facilities through the use of travel demand reduction and operational management strategies.

Consensus When a majority agrees upon a particular issue, while the dissenting remainder agrees that their input has been heard and duly considered and that the process as a whole was fair.

Cooperating Agencies (CA) Per NEPA, a cooperating agency is any federal agency that has jurisdiction by law or special expertise with respect to any environmental impact involved in a proposed project. Cooperating agencies are permitted, by request of the lead agency, to assume responsibility for developing information and preparing environmental analyses for topics about which they have special expertise.

Context Sensitive Solutions (CSS) An interdisciplinary approach that seeks effective, multimodal transportation solutions by working with stakeholders to develop, build and maintain cost-effective transportation facilities which fit into and reflect the project's scenic, economic, historic, and natural surroundings.

Corridor A corridor is a general path from one point to another.


Demographics Descriptive characteristics of populations. Examples include age, race and ethnicity, gender, income, employment and household status.

Design Concept In a major investment study, the type of facility (i.e. freeway, arterial, local road, etc.) being considered.

Destination The place where a trip ends.


Environment Surrounding conditions or circumstances. Usually used as a reference to nature (the natural environment) but also can include man-made conditions (the built environment).

Environmental Assessment (EA) A process of evaluating the likely environmental impacts of a proposed project or development, taking into account inter-related socio-economic, cultural and human-health impacts, both beneficial and adverse.

Environmental Factors In transportation, these factors include air, water and living (eco) systems, as well as community and social factors such as aesthetics/visual, archeology, culture, economics, history and noise.

Environmental Justice (EJ) Environmental Justice is the fair treatment and meaningful involvement of all people regardless of race, color, national origin, or income in development, implementation, and enforcement of environmental laws, regulations, and policies.

Environmental Mitigation Methods, strategies or actions to reduce the negative effects, direct, indirect and cumulative, of transportation project on the environment.

Environmental Protection Agency (EPA) EPA is the federal source agency of air quality control regulations affecting transportation.

Evaluation Criteria A standard or measure that permits a comparative evaluation of an alternative.


Fatality Any death on the transportation system that occurs as a result of a moving vehicle.

Federal Highway Administration (FHWA) Division of the U.S. Department of Transportation that funds highway planning and programs.

Finding of No Significant Impact (FONSI) The FONSI is a document that explains the reasons why an action will not have a significant effect on the human environment and, why, therefore, an Environmental Impact Statement (EIS) will not be required. The FONSI is a stand-alone document but is attached to the Environmental Assessment (EA) and incorporates the EA by reference.

Forecast A calculation or estimate of future conditions.


Geographic Information Systems (GIS) A computer software tool that is used to solve problems based on geographically related information. It is a system linked to a graphics system capable of collecting, storing, analyzing, manipulating and displaying spatial information.


Historic Property Historic property means any prehistoric or historic district, site, building, structure, or object included in, or eligible for inclusion in, the National Register of Historic Places maintained by the Secretary of the Interior. This term includes artifacts, records, and remains that are related to and located within such properties. The term includes properties of traditional religious and cultural importance to an Indian tribe or Native Hawaiian organization and that meet the National Register criteria.

Home Based Work Trip A trip to or from home for the purpose of one’s employment.


Illinois Department of Transportation (IDOT) The Illinois Department of Transportation has responsibility for planning, construction and maintenance of Illinois' extensive transportation network. This network encompasses highways, bridges, airports, public transit, and rail freight and rail passenger systems.

Infrastructure A term connoting the physical underpinnings of society at large, including, but not limited to, roads, bridges, transit, water and waste systems, public housing, sidewalks, utility installations, parks, public buildings and communications networks.

Intersection A point at which separate roadways cross, meet, or overlap.

Interstate System The system of highways that connects the principal metropolitan areas, cities, and industrial centers of the United States. The Interstate System also connects the U.S. to internationally significant routes in Mexico and Canada. The routes of the Interstate System are selected jointly by the state department of transportation for each state and the adjoining states, subject to the approval of the U.S. Secretary of Transportation.


Lake County Division of Transportation (LCDOT) County government division committed to providing safe, efficient, and well-maintained county highways and bikeways to improve the general welfare of travelers in Lake County communities and foster the orderly economic development of the county.

Lake County Forest Preserve (LCFPD) The Lake County Forest Preserve District is a special purpose unit of government whose mission is to protect nearly 31,000 acres of open space in Lake County.

Lake County Stormwater Management Commission (LCSMC) LCSMC mission is to coordinate the stormwater activities of more than 90 jurisdictions throughout Lake County.

Land Use Refers to how land and the structures (development) on it are used, i.e., commercial, residential, retail, industrial, etc.

Level of Service (LOS) A qualitative measure describing operational road (traffic) conditions and the perception of motorists of the existing conditions. Six levels of service are defined for each type of facility, ranging from A to F, with level of service A representing the best operating conditions and level of service F the worst. Initially used to define the road network, the concept has been expanded to include bicycle and pedestrian conditions.

Local Street A street intended solely for access to adjacent properties.


Metra Metra provides commuter rail service in the Chicago Metropolitan area. Metra, with 495 miles of track, serves 230 stations in the counties of Cook, DuPage, Lake, Will, McHenry and Kane.

Metropolitan Planning Organization (MPO) Formed in cooperation with the state, the Metropolitan Planning Organization (MPO) develops transportation plans and programs for the metropolitan area. For each urbanized area, an MPO must be designated by agreement between the Governor and local units of government representing 75% of the affected population (in the metropolitan area), including the central cities or cities as defined by the Bureau of the Census, or in accordance with procedures established by applicable State or local law. The MPO for the Chicago land area is Chicago Metropolitan Agency for Planning (CMAP).

Metropolitan Statistical Area (MSA) Census Bureau delineation for major metro areas in the U.S. Also includes standard (SMSA) and consolidated metropolitan statistical area (CMSA).

Mobility The ability to move or be moved from place to place. Typically, mobility is the ease with which movement can occur between geographic areas or parts of the region.

Mode, Intermodal, Multimodal Form of transportation, such as automobile, transit, bicycle and walking. Intermodal refers to the connections between modes and multimodal refers to the availability of transportation options within a system or corridor.

Model A mathematical formula that represents the activity and the interactions within a system so that the system may be evaluated according to various conditions: land use, population, households and employment (socio-economic), transportation, or others.


National Environmental Policy Act (NEPA) NEPA guides federally funded projects and projects that require a Federal permit to lessen potential damages to the environment. The NEPA process requires federal agencies to integrate environmental values into their decision-making process by considering the environmental impacts of their proposed actions and reasonable alternatives to these actions. Environmental factors such as air quality, wildlife, vegetation, water quality, wetlands, geology, neighborhoods, park/recreation areas, utilities, visual quality, and cultural resources will be assessed. NEPA encourages early and frequent coordination with the public and resource agencies throughout the project development process. Public comments that are received during the alternative analysis phase are considered in the draft environmental document. Following NEPA guidelines, a document called an Environmental Assessment will be prepared. The process calls for continuous environmental evaluations as alternatives are analyzed.

Network A graphic and/or mathematical representation of multimodal paths in a transportation system.

Non-Motorized Non-motorized transportation, also known as active transportation and human powered transportation, includes walking and bicycling, as well as small-wheeled transport (skates, skateboards, push scooters and hand carts) and wheelchair travel.


Operations, Operational Strategies How a transportation network functions; operational strategies are techniques that influence how a network functions. For example, traffic signals and signs are operational activities that control traffic.


Pace Pace primarily provides bus service in suburban areas outside the City of Chicago. Within the City of Chicago, the Chicago Transit Authority provides bus service.

Peak Hour The 60 minute period during which the largest volume of travel is experienced.

Peak Travel Period The period in the morning (a.m. peak period) and afternoon or evening (p.m. peak period) when additional transportation services are needed/provided to handle higher traffic/passenger volumes. The period begins when normal travel times are increased and ends when travel times are returned to normal. In the Chicago metropolitan area, the a.m. peak period is generally 6:00 a.m. to 8:00 a.m. and the p.m. peak period is 4:00 p.m. to 6:00 p.m. each weekday.

Person Trip A one-way trip made for any purpose, by any (usually vehicular) travel mode, by one person.

Problem Statement A concise narrative, prepared as part of a project needs study, defining the fundamental situation or circumstance to be solved. A problem statement will generally describe a particular situation in which an expected level of performance is not being achieved, and will list one or more important factors which cause or contribute to the unacceptable performance.

Project Study Team (PST) The working group for a project will consist of a Project Study Team (PST). The PST will make the ultimate project recommendations and decisions on this project and the membership of the PST will evolve as the understanding of the project’s context is clarified. Other responsibilities of the PST include expediting the project development process, identifying and resolving project development issues, promoting partnership with stakeholders to address identified project needs and working to develop consensus among stakeholders.

Public Participation The active and meaningful involvement of the public in the development of transportation plans and improvement programs. Federal transportation legislation regulations require that state departments of transportation and MPOs proactively seek the involvement of all interested parties, including those traditionally under served by the current transportation system.

Public Road Any road or street under the jurisdiction of and maintained by a public authority and open to public traffic.

Public Transit Generally refers to passenger service provided to the general public along established routes with fixed or variable schedules at published fares. Related terms include transit, mass transit, public transportation or paratransit. Transit modes include commuter rail, heavy or light transit, bus, or other vehicles designated for commercial transportation of non-related persons.

Purpose and Need The Purpose and Need incorporates detailed technical analysis and public involvement findings to date to define the purpose of the project and the need for the improvements.


Quality of Life A term used to describe the lifestyle conditions of an area. Conditions include the scale and depth of opportunities or choices in housing, employment, transportation, the natural environment, education, health care, and recreational and entertainment activities.


Region An entire metropolitan area including designated urban and rural sub-regions.

Regional Transportation Authority (RTA) The Regional Transportation Authority, created in 1973, oversees the operation and funding of public transit in the Chicago metropolitan area. There are three service boards under the RTA—the Chicago Transit Authority (CTA), Metra and Pace.

Regional Transportation Plan (RTP) A Regional Transportation Plan (RTP) is a long-term blueprint of a region’s transportation system. Usually RTPs are conducted every five years and are plans for thirty years into the future. The plan identifies and analyzes transportation needs of the metropolitan region and creates a framework for project priorities.

Reverse Commute Commuting (work) trips made from the central city to suburbs during the morning and the return trip to home during the afternoon.

Right-of-way (ROW) The land (usually a strip) acquired for or devoted to transportation purposes.


Single Occupant Vehicle (SOV) A SOV is a vehicle that carries only one occupant (the driver) to a destination.

Socioeconomic A term used to describe social and economic factors, generally resulting from an analysis of demographics of a population.

Stakeholder Involvement Group (SIG) The SIG provides input on various study elements including the definition of project issues and concerns, and developing evaluation of the potential alternatives. The SIG consists of community leaders from the study area, and stakeholders with expertise or technical interest in environmental, land use, transportation, and economic development that are affected by the study, as well as other representative stakeholders.

Stakeholder Involvement Plan (SIP) The SIP is a blueprint for defining methods and tools to educate and engage all stakeholders in the decision-making process for a project. The SIP provides the framework for achieving consensus and communicating the decision-making process between the general public, public agencies, and governmental officials to identify transportation solutions for the project.


Telecommuting The substitution, either partially or completely, of transportation to a conventional office through the use of computer and telecommunications technologies. Implies either work at home or at a satellite work center that is closer to an employee's home than the conventional office.

Traditional Commute Commuting (work) trips made from the suburbs to the central city during the morning and return trips to home during the afternoon.

Traffic Controls Traffic control systems are designed to reduce travel times, delays and stops, while also improving the average speed on arterial roadways and freeways. These systems include elements such as coordinated traffic signals, continuous optimization of timing plans, use of bus priority signal control systems, and implementation of computer-based traffic control and freeway traffic management.

Transportation Improvement Program (TIP) This is a document prepared by states and MPOs citing projects to be funded under federal transportation programs, typically for a three to five year period. Without TIP inclusion, a project is ineligible for federal funding.

Transportation Network Arrangement of transportation systems for the movement of passenger and cargo. Transportation systems include grid systems, radial networks, circumferential networks and eclectic networks.


Urbanized Area Area that contains a city of 50,000 or more population plus incorporated surrounding areas meeting set size or density criteria.

U.S. Department of Transportation (DOT) The principal direct federal funding and regulating agency for transportation facilities and programs. FHWA and FTA and units of the US DOT.


Vehicle Hours of Travel (VHT) The sum of time all vehicles spend traveling, calculated most typically over a 24-hour period. This statistic is most commonly summed over some area like county, but can also be calculated for specific routes or trip purposes like work.

Vehicle Miles of Travel (VMT) A standard area-wide measure of travel activity. The most conventional VMT calculation is to multiply the average length of trip by the total number of trips.

Volume-to-Capacity (V/C) The number of vehicles that travel on a road divided by the theoretical capacity of the road. Actual road capacity depends on a wide variety of factors such as lane width, pavement condition, total number of lanes, weather conditions, and more.