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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.

Active Traffic Management Strategies (ATMS)

Utilization of electronic signage to provide motorists advanced information on travel conditions.


One of a number of specific transportation improvement proposals, alignments, options, design choices, etc. in a study. Following detailed analysis, one improvement alternative is chosen for implementation.

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.

Bus-on-Shoulder Program

Select Pace Buses can use shoulder lanes to by-pass slow traffic, thus reducing their travel time and staying on schedule.

Congestion Pricing

Congestion pricing—sometimes called value pricing—is a way to provide travel options by harnessing the power of the market. Time sensitive travel can choose to pay a toll for reliable service during congested travel periods.

Context Sensitive Solutions (CSS)

Balance between mobility, community needs, and the environment while developing transportation projects. This is achieved through involving stakeholders early and continuously, addressing all modes of transportation, applying flexibility in the design, and incorporating aesthetics to the overall project.


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

Corridor Advisory Group (CAG)

Interactive group made up of elected officials and appointed representatives representing stakeholders that are directly affected by the project, and who have authority to enter into intergovernmental agreements.


The place where a trip ends.


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)

Concise report which evaluates the environmental effects and project-related social impacts of a project in order to evaluate their significance; it may include identifying measures to prevent, minimize, mitigate, or compensate for adverse environmental effects for which federal funding is being sought.

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.

Federal Highway Administration (FHWA)

Division of the U.S. Department of Transportation that funds highway planning and programs.


A calculation or estimate of future conditions.


A controlled-access, divided highway for through traffic. Intersections with other roads are separated by different road levels.


Commercial goods carried by a vehicle, usually a truck, plane, train or ship; cargo.

General Purpose Lane

A general purpose lane is a traffic lane that does not have any restrictions, such as time of day or type of vehicle that may use the lane.

Express Toll Lane

Express Toll (ETL) facilities consist of toll lane/s that provides a new travel choice for commuters in a congested corridor by offering substantial savings in travel time, along with a reliable and predictable travel service. All vehicles pay according to the payment schedule.

HOV or High Occupancy Vehicle

High Occupancy Vehicle (HOV) facilities serve to increase the total number of people moved through a congested corridor by offering two kinds of travel incentives: a substantial savings in travel time, along with a reliable and predictable travel service. Because HOV lanes carry vehicles with a higher number of occupants, they can move more people during congested periods, even if the number of vehicles that use the HOV lane is lower than on the adjoining general purpose lanes. In general, carpoolers, vanpoolers, and bus patrons are the primary beneficiaries of HOV lanes by allowing them to move through congestion travel conditions.

HOT or High Occupancy Toll

High Occupancy Toll (HOT) facilities are HOV facilities that have a toll required for their use if the vehicle high occupancy requirement is not met. Tolls may be variable depending on the level of congestion in the general purpose lanes, time of day or on the number of occupants in the vehicle.


Term used to describe higher capacity roads; also includes rights of way, bridges, railroad crossings, tunnels, drainage structures, signs, guardrails, and protective structures in connection with highways.

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 also includes properties of traditional religious and cultural importance to an Indian tribe or Native Hawaiian organization and that meet the National Register criteria.

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.

Illinois State Toll Highway Authority (ISTHA)

The Illinois State Toll Highway Authority has responsibility for planning, construction and maintenance of Illinois' tollway system.


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.

Intelligent Transportation Systems (ITS)

Use of computer and communications technology to facilitate the flow of information between travelers and system operators. Includes concepts such as "freeway management systems," "automated fare collection," and "transit information kiosks." Intelligent Vehicle Highway System (IVHS) technologies are a subset of ITS technologies.


A multilevel highway intersection arranged to allow vehicles to move from one road to another without crossing streams of traffic.


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

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.

Long Range Transportation Plan (LRTP)

In transportation planning, typically covers a twenty-year time span. Projects expecting to use federal funding must be included in the LRTP.

Managed Lane

Highway facilities or a set of lanes where operational strategies are pro-actively implemented and managed in response to changing conditions.

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).


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.


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.

Multi-Modal Transportation

Includes all modes of transportation for a complete transportation system. Examples: cars, trucks, bicycles, pedestrians, high occupancy vehicles, mass transit, rail.

National Ambient Air Quality Standards (NAAQS)

Federal standards that set allowable concentrations and exposure limits for various pollutants.

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.


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

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 is a public transportation agency which primarily provides bus service in suburban areas of Chicago metropolitan area. Within the City of Chicago, the Chicago Transit Authority provides bus service.

Park and Ride Facility

An access mode to transit in which patrons drive private automobiles or ride bicycles to a transit station, stop, or carpool/vanpool waiting area and park their vehicle in the area provided for park and ride patrons. They then ride the transit system or take a carpool or vanpool to their destinations.

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 9:00 a.m. and the p.m. peak period is 4:00 p.m. to 7:00 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.

Public/Private Partnership (P3)

A contractual arrangement between a public agency and a private entity to provide an on time and on budget project delivery, that allows for technical innovations, brings private sector efficiencies and provides an investment of private capital. Legislation would be needed to deliver the project as a P3.

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.


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.


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

Stakeholder Involvement

A process that will facilitate effective identification and understanding of the concerns and values of all stakeholders as an integral part of the project development process. It includes a formal written plan explaining how public input and comments will be obtained.

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.


A divided, fully access controlled roadway that assesses a toll or travel fee to pay for cost of construction, operation and maintenance.

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.


Generally refers to passenger service provided to the general public along established routes with fixed or variable schedules at published fares. Related terms include public 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.

Transportation (or Travel) Demand Management (TDM)

Strategies and collective efforts designed to achieve reductions in vehicular travel demand. In general, TDM does not require major capital improvements. It includes ridesharing, land use policies, employer-based measures, and pricing/subsidy policies.

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.

Transportation Management Area (TMA)

Defined in federal transportation legislation as all urbanized areas over 200,000 in population. Within a TMA, all transportation plans and programs must be based on a continuing and comprehensive planning process carried out by the Metropolitan Planning Organization (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 System Management (TSM)

Current TSM practices are fundamental traffic engineering actions taken to improve the operation of the highway system. TSM actions are usually categorized as "supply-side" (actions intended to increase the existing vehicle capacity on the system) and "demand-side" (actions that are designed to reduce vehicle demand on the system by increasing vehicle occupancy, see TDM). For example:

  • Traffic engineering improvements: left- and right-turn lanes, one-way streets, bus turn out lanes.
  • Traffic control improvements: traffic signal interconnection, use of bus priority signal control.

Travel Demand Management (TDM)

Measures designed to change single-occupant vehicle driver behavior with programs such as ridesharing (carpooling and vanpooling). Other demand-side actions include parking management strategies (like park and ride lots or preferential parking for carpooling/vanpooling) or transit service improvements (like express bus service, or by-pass ramps for buses).

Travel Demand Modeling

Travel demand modeling or travel forecasting is a major step in transportation planning. This is the process by which trip assignments are made to roadways, transit, and high-occupancy vehicles.

Travel Time

Customarily calculated as the time it takes to travel from "door-to door." In transportation planning, the measures of travel time include time spent accessing, waiting, and transferring between vehicles as well as time spent traveling.


A project, activity, or program funded in whole or in part under the direct or indirect jurisdiction of a Federal agency, including those carried out by or on behalf of a Federal agency; those carried out with Federal financial assistance; and those requiring a Federal permit, license or approval.

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.


The crossing of two or more traffic streams traveling in the same direction along a significant length of highway.


The smallest geographically designated area for analysis of transportation activity. A zone typically ranges in size from one to 10 square miles. Average zone size depends on total size of study area.