Common Acronyms





Agencies and Organizations

CRT Cumberland Region Tomorrow
CTS Clarksville Transit System
FAA Federal Aviation Administration
FHWA Federal Highway Administration
FTA Franklin Transit Authority
FTA Federal Transit Administration
GNAR Greater Nashville Association of Realtors
GNRC Greater Nashville Regional Council
LMT Leadership Middle Tennessee
MCHRA Mid-Cumberland Human Resource Agency
MDHA Metropolitan Development and Housing Agency
MNAA Metropolitan Nashville Airport Authority
MPC Metropolitan Planning Commission of Nashville-Davidson County
MPO Nashville Area Metropolitan Planning Organization
MTA Nashville Metropolitan Transit Authority
NCDC Nashville Civic Design Center
Rover Murfreesboro Public Transportation Department
RTA Regional Transportation Authority
TAMT Transit Alliance of Middle Tennessee
TDEC Tennessee Department of Environment and Conservation
TDOT Tennessee Department of Transportation
The TMA Group The Transportation Management Association Group
TPTA Tennessee Public Transportation Association
U.S. DOT U.S. Department of Transportation
U.S. HUD U.S. Department of Housing and Urban Development
U.S. EPA U.S. Environmental Protection Agency
ULI Urban Land Institute



Active Transportation Transportation which requires physical activity as part of the mode. Typically, active transportation refers to walking, bicycling and to transit, as transit trips begin and end with a walking or bicycling trip.
ADA Americans with Disabilities Act of 1990 - a federal law that requires public facilities (including transportation services) to be accessible to persons with disabilities including those with mental disabilities, temporary disabilities, and the conditions related to substance abuse.
ADT Average Daily Traffic - the number of vehicles passing a fixed point in a day, averaged over a number of days. The number of count days included in the average varies with the intended use of data. AADT, or annual average daily traffic, is the average calculated over the course of 365 consecutive days.
AVL Automated Vehicle Locator - a device that makes use of GPS to enable a transit agency or its customers the ability to track the location of a vehicle. AVL is a key ingredient in the development of real-time transit applications.
BRT Bus Rapid Transit - a high speed, high frequency bus service which typically operates in exclusive or dedicated lanes and outfitted with amenities more common to light rail transit (LRT) services including level boarding platforms and pre-boarding fare payment systems. BRT, which can be thought of as LRT on rubber tires, can be implemented incrementally unlike its rail counterpart.

Clean Air Act Amendments of 1990 - a federal law which provides for the designation of areas not in compliance with ambient air quality standards for ozone or particulate matter as "non-attainment," thus requiring further consideration of air quality impacts as part of the transportation planning process.



Central Business District - the area within a city, usually situated around the historic center of town, with the highest density or concentration of buildings.



Congestion Mitigation Air Quality - a federal grant program aimed at providing funding to transportation projects that assist in the reduction of vehicle emissions.


Commuter Rail A regional rail service that focuses the bulk of its service on peak work commuting times. Commuter rail typically shares a corridor with freight trains which limits frequency of passenger rail service. The Music City Star train between Nashville and Lebanon is a commuter rail service.
Complete Streets An internationally recognized approach to making roadways safe for all users including motorists, pedestrians, bicyclists, and transit riders and for people of all socioeconomic backgrounds. Complete streets initiatives typically also address the function of the roadway to support transportation, commercial, and social purposes.
Dedicated Funding A stream of revenue, typically from a specific tax or fee, that is formally or legally attached to a specific purpose. The federal gas tax is a form of dedicated funding for transportation that cannot be used for other programs. Most communities also have established a dedicated stream of funding to support transportation projects including public transit service and expansion. The alternative to dedicated funding is general fund revenue that is subject to the annual budgeting process.
E+C Existing plus Committed Transportation Network - also called a No-Build network, that consists of existing roadways and transit service plus currently funded roadway projects that will be completed within the next few years. The E+C network is typically used in studies which are conducted to test the impacts of future growth on traveling conditions.
EA Environmental Assessment - The process of identifying, predicting, evaluating and mitigating the biophysical, social, and other relevant effects of development proposals prior to major decisions being taken and commitments made. The purpose of the assessment is to ensure that decision-makers consider environmental impacts before deciding whether to proceed with new projects
EIS Environmental Impact Statement - A National Environmental Policy Act (NEPA) document that explains the purpose and need for a project, presents project alternatives, analyzes the likely impact of each, explains the choice of a preferred alternative, and finally details measures to be taken in order to mitigate the impacts of the preferred alternative.
EJ Environmental Justice - Derived from Title VI of the Civil Rights Act of 1964, and established by Executive Order, EJ requires federally funded plans and programs to assess their impact, either positive or negative, on traditionally underserved (e.g., low-income, minority, etc.) communities or segments of the population. The goal of EJ is to ensure public involvement of low income and minority groups in decision making to prevent disproportionately high and adverse impacts on low income and minority groups, and to ensure that these groups receive equal benefits from transportation improvements.
Federal-Aid System

A collection of roadways across the nation that are generally eligible for federal transportation funding for the purposes of expansion, maintenance, or improving safety.


Fiscal Constraint A requirement, originally of ISTEA, that all MPO transportation plans and program include a budget to demonstrate how projects can be paid for over the life of the plan with reasonably expected sources of funding. This is intended to ensure that MPO plans represent the top priorities for funding instead of an unlimited wish list of projects.
FY Fiscal Year - the 12 consecutive months used by a government agency or business for the purposes of financial bookkeeping. The federal fiscal year (FFY) runs from October through September.  The State of Tennessee's fiscal year runs from July through June. The MPO uses the federal fiscal year in its plans and programs.

Geographic Information System - a system for capturing, storing, and managing data which are used to create maps or conduct spatial or geographic analysis.


HIA Health Impact Assessment - An assessment conducted ideally in the planning phases of a built environment project which estimates any positive or negative impacts that a project may have on environmental or personal health. The assessment makes recommendations for improvements to the project to mitigate negative impacts such as reducing emissions or improving positive impacts such as increasing physical activity.

High Occupancy Toll - carpool or HOV lanes that can be used by single-occupancy vehicles who are willing to pay a toll.



High Occupancy Vehicle - often used to refer to carpool lanes. In Tennessee, vehicles carrying two (2) or more people receive this designation and may travel on freeways, expressways and other large volume roads in lanes designated for high occupancy vehicles. Motorcycles are also authorized to use these lanes.


HPMS Highway Performance Monitoring System - a collection of data and statistical information about the roadway system across the nation.
ISTEA Intermodal Surface Transportation Efficiency Act of 1991 - a federal law which restructured transportation planning and funding by requiring consideration of multimodal solutions, emphasis on the movement of people and goods as opposed to traditional highway investments, flexibility in the use of transportation funds, a greater role of MPOs, and a greater emphasis on public participation. ISTEA preceded TEA-21 and SAFETEA-LU.
ITS Intelligent Transportation System - the use of computer and communications technology to facilitate the flow of information between travelers and system operators to improve mobility and transportation productivity, enhance safety, maximize the use of existing transportation facilities, conserve energy resources and reduce adverse environmental effects; includes concepts such as “freeway management systems,” “automated fare collection” and “transit information kiosks.”

Level of Service - a qualitative assessment of a road’s operating condition, generally described using a scale of A (little congestion) to E/F (severe congestion). In the context of analyzing bicycle and pedestrian accommodations, LOS typically refers to the perceived safety or comfort of the roadway.


LRT Light Rail Transit - a form of rail transit that operates at moderate speeds with high frequencies within an urban or suburban environment. LRT operates throughout the day to serve a variety of travel purposes and provides enhanced passenger amenities like level boarding stations and pre-boarding fare payment. LRT is flexible and can operate in dedicated lanes or in mixed traffic (the former also called "streetcars"). LRT is different than heavy rail which operates in exclusive lanes at all times. LRT is typically powered trough overhead power lines. Heavy rail is typically powered by a third rail within the track system.
LRTP Long Range Transportation Plan - a federally-required document resulting from regional collaboration and consensus which serves as the defining vision for the region's transportation systems and services. The plan indicates all of the transportation improvements scheduled for funding over the next 20 years or more. It is fiscally constrained, i.e., a given program or project can reasonably expect to receive funding within the time allotted for its implementation.

Moving Ahead for Progress in the 21st Century - the federal transportation act passed by Congress and signed into law in 2012 that authorized federal surface transportation programs for FYs 2013 and 2014. It replaced SAFETEA-LU, its predecessor.



A term used to indicate that a project or a plan contains or addresses more than one mode of transportation. Multi-modal typically refers to roadway projects or transportation plans that include provisions for pedestrians, bicyclists, and public transit.


NEPA National Environmental Policy Act - Passed in 1970, NEPA requires federal agencies to integrate environmental values into their decision making processes by considering the environmental impacts of their proposed actions and reasonable alternatives to those actions.

Nitrous Oxide - the third largest greenhouse gas, nitrous oxide also attacks ozone in the stratosphere, aggravating the excess amount of UV light striking the earth's surface.


Obligated Funds

Funds that have been authorized by and committed to legally by a federal agency to pay for the federal share of the project cost.



Preliminary Engineering (phase of project) - a process to begin developing the design of the facilities and system, to analyze the function and operation of the system, evaluation cost efficiencies and prepare for the final design of the project.


PPP Public Participation Plan - a federally-required document that describes the MPO’s process for involving the public and interested stakeholders in the development and adoption of required plans and programs, and the formal procedures used to adopt or amend the Long-Range Transportation Plan, the Transportation Improvement Program, and Unified Planning Work Program.
Rapid Transit

A term used to refer to bus or rail transit that operates in exclusive or dedicated lanes in order to achieve travel speeds faster than transit operating in mixed traffic. See BRT and LRT for two types of regional rapid transit.



Right-of-Way - real property (land) that is used for transportation purposes; defines the extent of the corridor that can be used for the road and associated drainage.


SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act - a Legacy for Users - legislation enacted August 10, 2005, as Public Law 109-59. SAFETEA-LU authorizes the Federal surface transportation programs for highways, highway safety, and transit for the 5-year period 2005-2009. SAFETEA-LU was preceded by ISTEA and TEA-21, and superseded by MAP-21.
School Siting The process by which a community decides where to locate a new public school. The placement of schools and the zones of populations assigned to attend a school affect transportation patterns in the community as well as the modal types used to make a home to school trip.

State Implementation Plan (for air quality) - a state's regulations, policies, and strategies for meeting clean air standards and associated Clean Air Act requirements.



State Route - a roadway owned by a state government, often financed and maintained by the state.


STIP State Transportation Improvement Program - a federally-required priority list of transportation projects developed by the Tennessee Department of Transportation that is to be carried out within the four (4) year period following its adoption; must include documentation of federal and State funding sources for each project.Transportation projects in the state’s 11 urban areas are determined through Metropolitan Planning Organization process.
STP Surface Transportation Program (also L-STP or U-STP) - a federal grant program funded by the National Highway Trust Fund that is provided to states through the Federal Highway Administration to help maintain and expand the federal-aid system of roadways. L-STP provides funding to areas of 5,000 to 50,000 in population for improvements on routes functionally classified urban collectors or higher. U-STP Provides funding to Census designated urbanized areas over 50,000 in population (e.g. MPO areas based on US Census) for improvements on routes functionally classified urban collectors or higher.
TAZ Traffic Analysis Zone - a geographic unit used in travel demand modeling that contains current Census information and forecasts of future  population and jobs. MPO travel demand models predict the number of trips that will occur each day between zones within the region.

Technical Coordinating Committee - a standing committee of the MPO that is comprised of local planners and engineers, and staff from state agencies and transit agencies which work with the MPO staff to formulate plans and programs.



Transportation Disadvantaged - populations who are unable to transport themselves or to purchase transportation due to disability, income status, or age.


TDM Transportation Demand Management - a term that refers to a set of strategies to reduce traffic congestion through non-infrastructure means including policies or incentives that promote the use of carpooling or transit use and staggered work hours.
TEA-21 Transportation Equity Act for the 21st Century - federal legislation that authorized funds for all modes of transportation and guidelines on the use of those funds. Successor to ISTEA, the landmark legislation clarified the role of the MPOs in the local priority setting process. TEA-21vemphasized increased public involvement, simplicity, flexibility, fairness, and higher funding levels for transportation. TEA-21 preceded SAFETEA-LU.
TIP Transportation Improvement Program - a schedule of transportation projects developed by a metropolitan planning organization that is to be carried out within the four or five year period following its adoption; must include documentation of federal and State funding sources for each project and be consistent with adopted MPO long range transportation plans and local government comprehensive plans.
TOD Transit Oriented Development - a mixed-use development that is anchored by a transit station. The transit mode may include bus or rail, and the development may include uses such as housing, office and retail.
UPWP Unified Planning Work Program - an annual list of planning activities and studies that will be paid for with federal transportation funds and carried out by an MPO or its planning partners over the year or two following its adoption. The UPWP also serves as the MPO's annual operating budget.
V/C Ratio

Volume to Capacity Ratio - an engineering term that refers to roadway performance. V/C is a measure to show how a highway volume compares with a highway‘s designed capacity.


VHT Vehicle Hours Traveled - a measure of the amount of time that a population travels over the course of the average day or annually.

Vehicle Miles Traveled - a measure of traffic flow over some distance of roadway. VMT also can be used to indicate the total distance traveled by a population on a daily or annual basis.


VOC Volatile Organic Compounds - organic chemical compounds that have high enough vapor pressures under normal conditions to significantly vaporize and enter the atmosphere. Included among these compounds are dry-cleaning solvents and some constituents of petroleum fuels.