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NDLSD Glossary

General

• Accessible Pedestrian Signal (APS) - A traffic signal that provides auditory and/or vibrotactile information to pedestrians who are blind or have low vision.
• Adjacent Street Network – The local street grid to the west of North DuSable Lake Shore Drive.
• Arterial – Moderate to high capacity streets that connect commercial and residential areas.
• Categorical Exclusion (CE) - A category of actions which do not individually or cumulatively have a significant effect on the human environment.
• Chicago Metropolitan Agency for Planning (CMAP) - The Chicago Metropolitan Agency for Planning (CMAP) is the regional planning agency for northeastern Illinois (Cook, DuPage, Kane, Kendall, Lake, McHenry, and Will Counties). CMAP is providing year 2050 travel forecasts that are being used by the NDLSD project team.
• Collector – Low to moderate capacity streets that carry traffic from the interior of an area or community to the arterial system.
• Complete Streets – Complete streets policy ensures that streets are designed, operated and maintained to be safe, comfortable and convenient for all users.
• Design Year - Roadway Improvement projects are typically designed for a 20 year planning horizon. The proposed improvement needs to accommodate traffic projections 20 years into the future.
• Free Flow of Speed – The flow of motor vehicles at the posted speed limit of 40 miles per hour on the Outer Drive.
• Friction –The interaction between motor vehicles caused by merging and weaving between lanes
• Intersection - The general area where two or more roadways join or cross, including the roadway and roadside facilities for traffic movements within the area.
• Local Streets - Local streets provide maximum land access and minimum mobility. Access to a local street is on an as needed basis to allow property owners access to a transportation facility.
• May - A permissive condition allowing individual judgment and discretion in evaluation and decision-making. If the term is used in specifying a procedure, that procedure is optional.
• Merging – When two separate traffic lanes join with one another, causing motor vehicles from both lanes to combine into a single lane. This often takes place at entrance ramps along the Outer Drive.
• Multi-modal - Transportation involving more than one form of travel, i.e. pedestrians, bicycles, transit, and autos.
• Non-motorized transportation – Includes people walking and bicycling.
• Shall, Must - A mandatory condition. Users are obligated to adhere to the recommendations and applications presented in this context or to perform the evaluation indicated. If these terms are used in specifying a procedure, that procedure is mandatory.
• Should - An advisory condition. Users are strongly encouraged to follow the criteria and guidance presented in this context. If this term is used in specifying procedures, that procedure is recommended. Deviations from the specified procedure should be justified.
• Transit Priority Lanes – Lanes with designated signals to allow buses to move before other vehicles.
• Traffic Volume Change – Measures the change in number of NDLSD users that use the Outer Drive (or adjacent street network) between existing conditions and projected future conditions.
• Weaving – Motor vehicles changing lanes, especially in areas where lane changing commonly occurs at Outer Drive entrances and exits.

 Stakeholder Involvement and Agency Coordination

• Context Sensitive Solutions (CSS) - Context sensitive solutions (CSS) is a collaborative, interdisciplinary approach that involves all stakeholders to develop a transportation facility that fits its physical setting and preserves scenic, aesthetic, historic, and environmental resources, while maintaining safety and mobility.
• Cooperating Agencies - Agencies which have jurisdiction by law or special expertise with respect to environmental impacts associated with the NDLSD Alternatives.
• Lead Agency - The agency or agencies preparing or having assumed primary responsibility for preparing the environmental document.
• Project Study Group (PSG) - A group consisting of representatives from the Chicago Department of Transportation, the Chicago Park District, the Chicago Transit Authority, the Illinois Department of Transportation, and the Federal Highway Administration. This group provides technical oversight and expertise in key areas including the study process, agency procedures and standards, and technical approaches.
• Stakeholder - Anyone who is interested in or could be affected by the NDLSD project.
• Stakeholder Involvement Plan (SIP) – A plan that describes the overall stakeholder involvement process as well as specific opportunities for stakeholder involvement.
• Public Hearing – An officially required meeting held near the end of the study process to seek formal stakeholder input regarding the overall analysis and final recommendations.
• Public Informational Meetings – Held at various stages of the study process to provide information, seek stakeholder feedback and refine the process moving forward.
• Task Force – Consists of individuals, agencies and other groups that have a diverse set project related knowledge, expertise and interest in the NDLSD project. The Task Force uses their expertise to address a multitude of needs and opportunities related to the project and provides input and feedback on the Alternatives being evaluated, the proposed improvements, engagement, and various other aspects of the study. The major categories of Task Force membership include environmental, transportation, park user, business and communities.

Study Process

• Alternatives to be Carried Forward (ATBCF) – The NDLSD Alternatives that remain at the end of Level 2 Screening, which was the second round of evaluation. The ATBCF are evaluated in greater detail during Level 3 Screening.
• Environmental Impact Statement (EIS) – An official document required by NEPA for projects like this that summarizes the impacts, benefits, and costs of a project. The ongoing NDLSD study process is building components of the EIS, including the Purpose and Need, Alternatives Development, Alternatives Evaluation, Stakeholder Involvement, and Agency Coordination. A Draft EIS will be compiled and circulated prior to the Public Hearing, and a Final EIS will be issued following the Public Hearing.
• Environmental Studies - The investigations of potential environmental impacts to determine the environmental process to be followed and to assist in the preparation of the environmental document.
• Federally Funded/Regulated - Refers to the involvement of Federal funds and/or jurisdictional authority by any Federal agency for a proposed action.
• GO TO 2040 - The Chicago Metropolitan Agency for Planning (CMAP) is leading development of GO TO 2040, the comprehensive regional plan that will guide growth in Cook, DuPage, Kane, Kendall, Lake, McHenry, and Will Counties through mid-century and beyond. In addition to land use and transportation, GO TO 2040 also addresses the full range of quality-of-life issues, including the natural environment, economic development, housing, and human services such as education, health care and other social services.
• Level 1 Screening – A high level review to identify NDLSD Alternatives with Major Flaws (relatively higher costs or impacts).
• Level 2 Screening –Level 2 Screening assesses how effectively each alternative addresses the transportation problems (Purpose and Need). It also involves a second round of general environmental review
• Level 3 Screening – Level 3 Screening includes an expanded set of performance evaluation factors and final environmental review. It concludes with the identification of a Preferred Alternative.
• Metropolitan Planning Organization (MPO) - The Federal government and local officials designate local planning agencies to assure that projects undertaken with Federal funds are consistent with the regional transportation and land use planning in the area. For northeastern Illinois the MPO is the Chicago Metropolitan Agency for Planning (CMAP). **Note: CMAP staff support the MPO. The MPO is actually the Policy Committee, which is comprised mostly of outside parties.**
• Moving Ahead for Progress in the 21st Century (MAP-21) - MAP-21 is a milestone for the U.S. economy and the Nation's surface transportation program. By transforming the policy and programmatic framework for investments to guide the system's growth and development, MAP-21 creates a streamlined and performance-based surface transportation program and builds on many of the highway, transit, bike, and pedestrian programs and policies established in 1991.
• National Environmental Policy Act of 1969 (NEPA) - Landmark environmental legislation which set forth a national policy for and is the nation's legal basis for ensuring the protection and enhancement of the quality of the human environment. The overall framework for the NDLSD study must conform with NEPA.
• ON TO 2050 – Developed by the Chicago Metropolitan Agency for Planning, this is the second comprehensive regional plan developed by the agency that guides growth in Cook, DuPage, Kane, Kendall, Lake, McHenry, and Will Counties. This plan builds on the first comprehensive plan, GO TO 2040. This plan guides transportation investments and frames regional priorities on development, the environment, the economy, and other issues affecting quality of life.
• Purpose of and Need for Action - The Purpose and Need is a concise summary of the transportation problems to be addressed by the project.
• Range of Alternatives – The initial group of alternatives that are developed for evaluation.
• Scoping - An early and open process for determining the scope of issues to be addressed in the environmental document and for identifying potentially significant issues related to the proposed action.
• Section 106 of the National Historic Preservation Act of 1966 - Section 106 requires that a Federal agency or an agency utilizing Federal funding consider the effects a project may cause to a property which is on or eligible for the National Register of Historic Places.
• Section 4(f) of the USDOT Act of 1966 -Section 4(f) requires that all DOT agencies avoid the use of any significant publicly owned park, recreational area, wildlife and waterfowl refuge, or historic site, unless there is no prudent and feasible alternative to the use of that land. The NDLSD project is within Lincoln Park, which is considered both a Section 4(f) and a Section 106 resource.
• Section 404 Permit - Beginning in 1899 the U.S. Army Corps of Engineers was given regulatory function over public waterways. Public waterways at that time included rivers, harbors and other bodies of water which were navigable. In 1972 the Federal Water Pollution Control Act expanded the Corps regulatory function to include oversight of the "discharge of dredge material". Additionally, a definition of the "Waters of the United States" was also included in this law which expanded the Corps jurisdiction to include tributaries of navigable waters. In response to Section 404 of this 1972 law, a Federal permit process was established which requires that if a project will impact the Waters of the United States, all practical alternatives which avoid and minimize impacts must be evaluated.
• Section 6(f) Lands - Lands which had Land and Water Conservation (LAWCON) funds involved in their purchase or development.
• Strategic Regional Arterial (SRA) - The Strategic Regional Arterial system is a network of approximately 1,500 miles of existing roads in northeastern Illinois. The system includes routes in Cook, DuPage, Kane, Lake, McHenry, and Will Counties. Creation of the SRA system is a major component of Operation GreenLight, an eight-point plan to deal with urban congestion and improve regional mobility. The plan was developed by IDOT in cooperation with the Illinois Tollway, CMAP ATS, NIPC and the Regional Transportation Authority (RTA). The SRA system, which was first designated as part of the 2010 Transportation System Development Plan adopted by regional planning agencies and continues as a component of the 2040 Regional Transportation Plan (GOTO 2040), is intended to supplement the existing and proposed expressway facilities by accommodating a significant portion of long-distance, high volume automobile and commercial vehicle traffic in the region.
• Wetlands (Federal) - Those areas inundated or saturated by surface or ground water at a frequency and duration sufficient to support, and that under normal circumstances do support, a prevalence of vegetation typically adapted for life in saturated soil conditions. Wetlands generally include swamps, marshes, bogs, and similar areas.
• Wetlands (Illinois) - Land that has a predominance of hydric soils (soils which are usually wet and where there is little or no free oxygen) and that is inundated or saturated by surface or groundwater at a frequency and duration sufficient to support, and that under normal circumstances does support, a prevalence of hydrophytic vegetation (plants typically found in wet habitats) typically adapted for life in saturated soil conditions. Areas which are restored or created as the result of mitigation or planned construction projects and which function as a wetland are included within this definition even when all three wetland parameters are not present.

NDLSD Study Alternatives

• Context Tailored Treatments with Transit Advantages Alternatives (CTT + TA) – Options which bring NDLSD to modern standards and include spot transit improvements (Transit Advantage features). The top performing CTT Alternative has been carried forward to serve as both a standalone alternative (The Essential) as well as the base for all other alternatives.
• Managed Lanes Alternatives (ML) – Options that include the base CTT improvements and convert one or more existing general purpose lanes to a bus only or tolled managed lane. The managed lane is designed to provide high mobility for buses and potentially some autos. The remaining ML alternatives include the Exchange, Flex and Double Flex,
• No Action Alternative – The No Action Alternative assumes that routine maintenance is performed on North DuSable Lake Shore Drive, but no additional trail, transit or roadway improvements would be made to NDLSD by the year 2050. The No Action Alternative is used as a basis for comparing to other “Build” Alternatives.
• Transit Advantage (TA) Features – Spot mobility improvements for transit vehicles, such as queue jump lanes and bus priority signals. Other transit features include bus turnarounds and bus staging and layover areas.
• Transitway Alternatives (TW) - Options that include the base CTT improvements and add dedicated transit lanes to improve bus mobility. The remaining TW alternative is the Addition.

Travel Management Strategies

• Bus Priority Signal – Traffic signals at junctions that can be actuated by buses to bring up the green phase, which provides mobility advantage for transit. Bus Priority Signals are used in combination with Queue Jump Lanes.
• Bus Turnarounds – Provides a dedicated turnaround space for buses (e.g., after buses reach the eastern end of their route, they can turn to head west).
• Bus Layovers – Provides a staging area for buses prior to beginning their routes.
• Dynamic Tolling – A toll that changes in price depending on the number of cars on the road at a certain time. Dynamic tolling is used to maintain free flow speeds by limiting the number of cars in a lane.
• General Purpose Lane (GPL) – Traffic lanes that are designated for all motor vehicles, without management strategies such as tolling or bus only operation.
• Managed Lane (ML) – A traffic lane that includes management strategies such as tolling or bus only operations.
• Queue Jump Lane – Transit only lanes provided at junction ramps to allow buses to bypass other traffic while entering or exiting the Outer Drive. The Queue Jump Lanes would work in combination with Bus Priority Signals.
• Rectangular Rapid Flashing Beacon (RRFB) - A warning device at uncontrolled or midblock crossings, where pedestrians push a button to activate rapid flashing yellow LED lights to alert drivers to stop.
• Right-of-Way - Property owned by a government agency used for the construction of public facilities like a roadway or a bridge.
• Road Diet - A road diet reduces the amount of space for motor vehicles, either by eliminating through lanes or shrinking the width of lanes. The reclaimed space from a road diet is then re-allocated for other uses, such as turn lanes, bus lanes, pedestrian refuge islands, bike lanes, or more sidewalk space. Road diets often involve converting a four- or five-lane roadway into a three-lane street.
• Spot Safety Improvement – Providing enhancements that address safety problems at specific locations such as intersections or areas of the roadway.
• Static Tolling – A toll that stays the same regardless of demand or the time of day.
• Time of Day Tolling – Tolling at a certain rate based on the time of day, usually during peak travel times in the morning and evening.
• Transportation System Management (TSM) - Transportation system management optimizes the performance of existing infrastructure by implementing projects designed to conserve capacity and improve safety and reliability.
• Wayfinding – Signs, maps and other graphic or audible methods to convey location and direction to travelers.

Outer Drive Design Concepts

• At Grade - On the same level as the adjacent park space.
• Backshore Berm – A raised landscaped area along the eastern edge the Outer Drive, which is designed to prevent wave overtopping. A backshore berm is one component of the overall NDLSD shoreline protection strategy.
• Below Grade – Below the level of the adjacent park space.
• Direct Managed Lane Access – Access provided to the Managed Lane(s) from a dedicated ramp in the median of the Outer Drive.
• Forward Compatibility – When one design alternative contains features which are consistent (“compatible”) with other alternatives and could potentially allow one alternative to be later converted to another alternative (following the appropriate additional review and approval) if conditions changed in the future.
• Grade Separation – Separating conflicting flows of people walking, biking or driving by using underpass or overpass structures.
• Intermittent Access – Access to a specific traffic lane from the general purpose ramps and lanes. In the context of NDLSD, traffic would access the Managed Lane from the general purpose lanes, in the Managed Lanes alternatives.
• Perched Beach – A sand beach that is raised above the prevailing level of the lakebed and contained by an underwater wall, which is designed to absorb and dissipate wave energy and minimize wave damage to park space and other infrastructure on the inland side of the beach. The beach may also be used for recreational purposes. A Perched Beach is one component of the overall NDLSD shoreline protection strategy.
• Revetment Wall – A stepped concrete wall placed along the shoreline, which is designed to absorb and dissipate wave energy and minimize wave damage to park space and other infrastructure on the inland side of the wall. The steps of the wall may also be used for recreational purposes such as sitting or strolling. A Revetment Wall is one component of the overall NDLSD shoreline protection strategy.
• Roadway Grade – The level of the roadway relative to the prevailing grade (or level) of its surroundings. The three general terms used for this measurement are: at grade, below grade, above grade.
• Safety Zone – A 10-foot space along the outside edges of NDLSD that is clear of any obstructions. The clear zone is intended to improve safety by providing emergency pull-off space for disabled vehicles, incident management, and speed enforcement.
• Shoreline Protection Techniques – Techniques generally used to safeguard shoreline facilities from the force of wave action during large storm events. Major elements include backshore berms, swales, revetment walls and submerged stone benches.
• Submerged Stone Bench – A pile of large stones that are placed underwater on the lakebed adjacent to the shoreline, which is designed to absorb and dissipate wave energy before it reaches the shoreline. A Stone Bench is one component of the overall NDLSD shoreline protection strategy.

NDLSD Study Alternatives Development and Evaluation

• Average Daily Traffic (ADT) - The calculation of average traffic volumes in both directions of travel in a time period greater than one day and less than one year and divided by the number of days in that time period.
• Capacity Analysis - A study done to determine the quality of operation of a given intersection or roadway segment. The quality of operation is expressed in terms of a Level of Service (LOS).
• Geographic Information System (GIS) - Geographic information system (GIS) combines hardware, software, and data. GIS organizes the data in many ways that can display patterns and trends.
• Level of Service (LOS) - A qualitative concept which has been developed to characterize degrees of congestion as perceived by motorists. Letter designations, A through F, have been correlated to quantitative measures based on the amount of delay experienced at an intersection. Level A represents the best conditions and level F the worst.
• Major Flaw Review - Evaluation that reveals a significantly greater cost compared to the other alternatives and therefore not financially feasible, or there are severe and unacceptable socio-economic or environmental impacts.
• Mitigation - Includes the following items:

• Avoiding the impact altogether by not taking a certain action or parts of an action.
• Minimizing impacts by limiting the degree or magnitude of the action and its implementation.
• Rectifying the impact of repairing, rehabilitating, or restoring the affected environment.
• Reducing or eliminating the impact over time by preservation and maintenance operations during the life of the action.
• Compensating for the impact by replacing or providing substitute resources or environments.

• Mitigation Measures - Activities identified in the environmental process intended to lessen the severity of any unavoidable project impacts.
• Best Management Practices (BMP) - Best management practices (BMPs) are used to manage roadway runoff and improve water quality. Examples of BMP’s include bioswales and bioretention ponds, which can store and filter roadway runoff.
• Mode Share – The percentage of trips using a particular mode of travel, such as transit, auto, people who bike, and people who walk.
• Mode Shift – When users of one mode of transportation (i.e. motor vehicles) change their travel behavior and start using a different mode of transportation (i.e. transit) instead.
• Origin-Destination (O-D) – Used to determine travel patterns, an OD study analyzes travel behavior from the start of a journey (origin) to the end point (destination).
• Peak Hour - The single hour in the day during which the maximum traffic volume occurs on a particular roadway. Peak hours are further classified as an A.M. peak hour, a P.M. peak hour, or a weekend peak hour.
• Peak Period – The relative highest volume during a 1 or 2 hour portion of a day. There are typically two peak periods, which correspond to the morning and evening commute.
• Person Throughput – The total number of persons using a transportation facility, regardless of travel mode. Used as a measure of efficiency.
• Roadway Capacity - The capacity of a roadway is defined as the maximum hourly rate at which vehicles can reasonably be expected to travel through an intersection or section of roadway during a given time period. Some factors having a primary influence on the capacity of an intersection or roadway segment are: the number and width of lanes, other geometric considerations (sight distance, approach grades, turning radii), vehicle mix, turning percentages and signal timings.
• STOPS model – A travel demand modeling software package from the Federal Transit Administration that applies a set of travel models to predict detailed transit travel patterns for the No-Build and Build Alternatives of projects intended to improve transit service. (STOPS stands for Simplified Trips-on-Project Software)
• Transit Catchment Area – An area generally within a half mile of a transit stop that illustrates the local area served by a transit service.
• Travel Demand Model (TDM) – A computer program that simulates current and future travel, primarily for autos and transit. The TDM is one of the tools used for evaluating transportation alternatives and provides a big picture or “macro” view of travel performance.
• Transit Mobility – Bus travel times.
• Transit Reliability – The variability in bus travel times. A lower variation in bus travel times means higher reliability.
• Travel Mode – A particular method for traveling, such as by auto, bus, rail, walking, or bicycling.
• Vehicular Mobility – Auto travel times.
• Vehicular Delay - The primary performance measure on interrupted flow facilities, especially at signalized intersections. For this element, average control delay is measured, which is expressed in seconds per vehicle. Control delay includes the time vehicles are slowing down approaching a traffic signal or stopped at the intersection.
• VISSIM model – A computer program that simulates current and future auto and transit travel at a corridor or “micro” level. Output from the Chicago Metropolitan Agency for Planning’s Travel Demand Model (CMAP TDM) is used as inputs for the VISSIM model.

Please note that all definitions provided on this page are in context to the North DuSable Lake Shore Drive Phase I Study. The following terms may have different applications in other transportation and infrastructure projects.

Acronyms