Glossary of Transportation Planning Acronyms & Terms

The transportation arena has a language all its own. Learn commonly used words, acronyms and phrases.

Joey Kotfica

While MTC strives to use plain language, acronyms and jargon invariably creep into many discussions about transportation. To help you understand unfamiliar terms, we offer the following glossary of commonly used words, acronyms and phrases.


A one-stop phone and web source for up-to-the-minute Bay Area traffic, transit, rideshare and bicycling information. 511 consolidates the Bay Area's diverse transportation network, including highways, bus routes, rail transit, ferry lines, commercial airports, toll bridges and bikeways including the nine-county Bay Trail.

Call 511 or visit 511.org.

AB 32

Assembly Bill 32, also known as the California Global Warming Solutions Act of 2006, is a state law that requires a statewide reduction in greenhouse gas emissions to 1990 levels or lower by the year 2020. AB 32 was the first program in the country to take a comprehensive, long-term approach to addressing climate change.

(ABAG) Association of Bay Area Governments

A voluntary association of counties and cities in the nine-county San Francisco Bay Area. ABAG provides demographic, financial, administrative, training and conference services to local governments and businesses. Has one voting seat on MTC.

Affordable Housing & Sustainable Communities Program

The California Strategic Growth Council’s AHSC program is a statewide competitive program to provide grants and affordable housing loans for compact transit-oriented development and related infrastructure and programs that reduce greenhouse gas emissions. The program is funded by Cap and Trade auction proceeds.

Article XIX Restriction

A provision in the California Constitution that limits the use of state gasoline tax revenues to projects related to roadway (including bicycle and pedestrian projects) or fixed guideway (rail or trolley coach) improvements.

(BAAQMD) Bay Area Air Quality Management District

(Also known as the Air District.) Responsible for protecting air quality in the nine-county Bay Area; regulates industry and employers to keep air pollution in check and sponsors programs to clean the air.

(BAHA) Bay Area Headquarters Authority

BAHA oversees the management and operation of the San Francisco office building for MTC, the Association of Bay Area Governments, the Bay Area Air Quality Management District and the San Francisco Bay Conservation and Development Commission.

(BAHFA) Bay Area Housing Finance Authority

Established by the state Legislature in 2019, the Bay Area Housing Finance Authority's mandate is to create regional solutions that meet the Bay Area's affordable housing needs. BAHFA is the first regional housing finance authority in California, and works together with MTC and the Association of Bay Area Governments (ABAG).

(BAIFA) Bay Area Infrastructure Financing Authority

BAIFA, organized as a joint powers authority between MTC and the Bay Area Toll Authority, oversees the planning, financing, construction and operation of freeway express lanes and related transportation projects.

(BARC) Bay Area Regional Collaborative

BARC coordinates the planning efforts of MTC, the Association of Bay Area Governments (ABAG), the Bay Area Air Quality Management District (BAAQMD) and the Bay Conservation and Development Commission (BCDC). Formerly known as the Joint Policy Committee.

(BATA) Bay Area Toll Authority

BATA, acting as a separate legal entity of MTC, administers all toll revenues from the Bay Area’s seven state-owned toll bridges. The state Legislature created BATA in 1998.

Bay Area Partnership

Often referred to simply as “The Partnership,” this is a confederation of the top staff of various transportation agencies in the region, including MTC, public transit agencies, county transportation agencies, city and county public works departments, ports, Caltrans and the U.S. Department of Transportation, as well as environmental protection agencies. The Partnership works by consensus to improve the overall efficiency and operation of the Bay Area’s transportation network, including developing strategies for financing transportation improvements.

(BCDC) Bay Conservation Development Commission

BCDC is a California state planning and regulatory agency with regional authority over the San Francisco Bay, the Bay’s shoreline band, and the Suisun Marsh. Created in 1965, BCDC is the nation’s oldest coastal zone agency.

(Caltrans) California Department of Transportation

The state agency that owns, operates and maintains California’s highway system.

Capital Funds

Money to cover one-time costs for construction of new projects — such as roads, bridges, bicycle/pedestrian paths, transit lines and transit facilities — to expand the capacity of the

Census Data

Bay Area Census Data is information used by transportation planners to make projections about future Bay Area travel patterns, housing needs and the like. Required by the U.S. Constitution, the U.S. Census is a complete enumeration of the population conducted every 10 years by the U.S. Census Bureau (the last one was completed in 2020).

(CEQA) California Environmental Quality Act

Adopted in 1970, this law requires state and local agencies to consider the environmental consequences of decisions that involve changes to the environment, and to avoid or mitigate significant environmental impacts, if feasible. Depending on the potential effects, a further and more substantial review may be conducted in the form of an environmental impact report (EIR).

(CMAs) Congestion Management Agencies

More commonly known as County Transportation Agencies, CMAs are responsible for preparing and implementing a county’s Congestion Management Program. Many CMAs double as a county’s transportation sales tax authority.

(CMAQ) Congestion Mitigation and Air Quality Improvement Act

A federal source of funding for projects and activities that reduce congestion and improve air quality, both in regions not yet attaining federal air quality standards and those engaged in efforts to preserve their attainment status.

Committed Revenues

Revenues that are dedicated by law, ballot measure or prior MTC programming actions to specific transportation investments. Committed revenues comprise the vast majority of all funds identified in the long-term regional transportation plan. (Also see “Uncommitted Revenues.”)

Communities of Concern

Formerly known as Communities of Concern, Equity Priority Communities are census tracts that have a significant concentration of both people of color and low-income households at specified thresholds of significance, or that have a concentration of three or more of six other factors but only if they also have a concentration of low-income households.


A process in which transportation plans and spending programs are reviewed to ensure they are consistent with federal clean air requirements; transportation projects collectively must not worsen air quality.

(CTAs) County Transportation Agencies

Sometimes known as Congestion Management Agencies, CTAs are responsible for preparing and implementing a county’s Congestion Management Program. Many CTAs double as a county’s transportation sales tax authority.

(CTC) California Transportation Commission

A state-level commission, consisting of nine members appointed by the governor, that establishes priorities and allocates funds for highway, passenger rail and transit investments throughout California. The CTC adopts the State Transportation Improvement Program, or STIP, and implements state transportation policy.

(EIR) Environmental Impact Report

The EIR is an information document used for decision-making that discloses significant adverse impacts, identifies feasible mitigation measures, and analyzes project alternatives. (Also see CEQA.)

Environmental Justice

This term stems from a Presidential Executive Order to promote equity for disadvantaged communities and to promote the inclusion of racial and ethnic populations and low-income communities in decision-making. Local and regional transportation agencies must ensure that services and benefits, as well as burdens, are fairly distributed to avoid discrimination.

Equity Analysis

Consistent with federal requirements for environmental justice, MTC conducts an equity analysis covering the 25-year regional transportation plan to determine how the benefits and burdens of the plan’s investment strategy affect minority and low-income communities.

Equity Priority Communities

Formerly known as Communities of Concern, Equity Priority Communities are census tracts that have a significant concentration of both people of color and low-income households at specified thresholds of significance, or that have a concentration of three or more of six other factors but only if they also have a concentration of low-income households.

(FAST) Fixing America's Surface Transportation Act

The FAST Act established funding levels and federal policy for our nation’s highways and public transit systems for fiscal years 2016-2020. The $305 billion, five-year bill maintains the core highway and transit funding program established by its predecessor MAP 21, and establishes the National Highway Freight Program, a formula program focused on goods movement.

(FHWA) Federal Highway Administration

U.S. Department of Transportation agency responsible for administering the federal highway aid program to individual states, and helping to plan, develop and coordinate construction of federally funded highway projects. FHWA also governs the safety of hazardous cargo on the nation’s highways.

Financial Constraint

A federal requirement that long-range transportation plans include only projects that have a reasonable expectation of being funded, based upon anticipated revenues. In other words, long-range transportation plans cannot be pie-in-the-sky wish lists of projects. They must reflect realistic assumptions about revenues that will likely be available looking forward at least 20 years.

Flexible Funding

Unlike funding that flows only to highways or only to transit by a rigid formula, this is money that can be invested in a range of transportation projects. Among federal transportation programs, examples of flexible funding categories include the Surface Transportation Program (STP) and the Congestion Mitigation and Air Quality Improvement (CMAQ) program.

(FSP) Freeway Service Patrol

The Bay Area Freeway Service Patrol is a congestion management program implemented by the Metropolitan Transportation Commission Service Authority for Freeways and Expressways (MTC SAFE), the California Department of Transportation (Caltrans) and the California Highway Patrol (CHP). All free of charge to the motorist, FSP drivers rove the freeways during peak congestion hours to provide quick response to freeway incidents. Their work reduces potential for recurrent congestion, thereby increasing motorist safety and decreasing auto emissions.

(FTA) Federal Transit Administration

U.S. Department of Transportation agency that provides financial assistance to help plan, build and operate rail, bus and paratransit systems. The agency also assists in the development of local and regional traffic reduction programs.

(GHG) Greenhouse Gases

Any of the gases — including carbon dioxide, methane and oxides of nitrogen — whose absorption of solar radiation is responsible for the greenhouse effect, in which the atmosphere allows incoming sunlight to pass through but absorbs heat radiated back from the earth’s surface.

Growth Geographies

Locations used to guide where future growth in housing and jobs would be focused over the next 30 years. These locations are identified for growth either by local cities and counties or because they are located close to transit or access to opportunity. The four types of Growth Geographies in Plan Bay Area 2050 are:

  • Priority Development Areas (PDAs): Areas generally near existing job centers or frequent transit that have been identified by towns, cities or counties for housing and job growth
  • Priority Production Areas (PPAs): Locally identified places for job growth in middle-wage industries like manufacturing, logistics or other trades. An area must be zoned for industrial use or have a strong industrial use to be a PPA
  • Transit-Rich Areas (TRAs): Areas near rail, ferry or frequent bus service that were not already identified as PDAs. Specifically, these are areas where at least 50% of the area is within 1/2 mile of an existing rail station or ferry terminal (with bus or rail service), a bus stop with peak service frequency of 15 minutes or less, or a planned rail station or planned ferry terminal (with bus or rail service)
  • High-Resource Areas (HRAs): Places identified by the state that have well-resourced schools and access to jobs and open space – among other advantages – that may have historically rejected more housing growth. This designation only includes places that meet a baseline transit service threshold of bus service with peak headways of 30 minutes or better

(HOV Lane) High-Occupancy-Vehicle Lane

The technical term for a carpool lane, commuter lane or diamond lane.


The term “mode” is used to refer to a means of transportation, such as automobile, bus, train, ship, bicycle and walking. Intermodal refers specifically to the connections between modes.

Lifeline Transportation Network

The Lifeline Transportation Network is an MTC initiative to enhance low-income residents’ access to key destinations such as job centers, government buildings and medical facilities during both peak commute periods and off-peak hours. While most of the Lifeline network identified by MTC is already served by existing transit routes, some low-income communities and/or destinations are not served by transit or lack service at specific times of day. MTC is working with transit operators and potential funding partners to fill these gaps in the network.

Managed Lanes

Unlike general purpose freeway lanes, managed lanes are those with access limitations due to occupancy requirements or pricing, such as carpool and express lanes.

(MPO) Metropolitan Planning Organization

A federally required planning body responsible for the transportation planning and project selection in its region; the governor designates an MPO in every urbanized area with a population of over 50,000. MTC is the nine-county San Francisco Bay Area’s MPO.

(MTC) Metropolitan Transportation Commission

The transportation planning, financing and coordinating agency for the nine counties of the San Francisco Bay Area.


Micromobility includes ways of getting around that are fully or partially human-powered — such as bikes, e-bikes and e-scooters and mobility-assistance devices/wheelchairs. Most commonly, micromobility vehicles do not exceed 15mph.

(OBAG) One Bay Area Grant

The One Bay Area Grant Program is a funding approach designed to support the implementation of Plan Bay Area, the region’s Sustainable Communities Strategy. OBAG taps federal funds to maintain MTC’s commitments to regional transportation priorities while also advancing the Bay Area’s land-use and housing goals.

Ozone Attainment Strategy

This plan details the strategy by which the Bay Area will comply with federal ozone — or “smog” — standards. The Ozone Attainment Strategy is prepared by the Bay Area Air Quality Management District, the Association of Bay Area Governments and MTC, then submitted for review and approval by the California Air Resources Board and the U.S. Environmental Protection Agency. The plan provides a transportation “emissions budget” that identifies allowable levels of pollution from motor vehicles traveling in the Bay Area. (Also see “Conformity.”)


Door-to-door bus, van and taxi services used to transport elderly and disabled riders. Sometimes referred to as dial-a-ride service, since trips are made according to demand instead of along a fixed route or according to a fixed schedule. Learn about MTC’s commitment to Access, Equity & Mobility.

Performance Measures

Indicators of how well the transportation system or specific transportation projects will improve transportation conditions. Used in assessing a project for funding.

Plan Bay Area

Plan Bay Area is the long-range transportation and land-use plan jointly adopted in 2013 by MTC and the Association of Bay Area Governments (ABAG). It was the first regional plan for the nine-county San Francisco Bay Area to incorporate a state-mandated Sustainable Communities Strategy.

Plan Bay Area 2040

Plan Bay Area 2040, adopted by MTC and ABAG in 2017 is the Bay Area’s current long-range regional transportation, land use and housing plan. A narrowly-focused update of the original Plan Bay Area, this plan is designed to support a growing economy, provide more housing and transportation choices, and reduce pollution caused by transportation.

Plan Bay Area 2050

Plan Bay Area 2050, adopted by MTC and ABAG in October 2021, charts a course through 2050 for transportation investment, land-use planning and housing development in the nine-county region by focusing on four key elements—the economy, the environment, housing and transportation—and identifies a path to make the Bay Area more equitable for all residents and more resilient in the face of unexpected challenges.

Plan Bay Area 2050+

This is a limited and focused update to Plan Bay Area 2050, the current long-range regional plan for the Bay Area. Work is underway on Plan Bay Area 2050+, with an anticipated adoption in fall 2025. 

(PCAs) Priority Conservation Areas

Priority Conservation Areas (PCAs) are identified through consensus by local jurisdictions and park/open space districts as lands in need of protection due to pressure from urban development or other factors. PCAs can include open spaces that provide scenic, recreational, agricultural, natural resource and/or ecological value and ecosystem functions.

(PDAs) Priority Development Areas

Priority Development Areas (PDAs) are places identified by Bay Area cities or counties as areas for investment, new homes and job growth. Visit the PDAs web page for additional criteria in order for a place to be designated as a PDA.


  1. Verb: To assign funds to a project that has been approved by MTC, the state or another agency.
  2. Noun: A system of funding for implementing transportation projects or policies, such as through the State Transportation Improvement Program. (Also see “STIP.”)


(RAWG) Regional Advisory Working Group

An advisory group set up to advise staff of ABAG and MTC on development of Plan Bay Area. Open to the public, participants include staff representatives of local jurisdictions (CTAs, planning directors, transit operators, public works agencies) as well as representatives from the business, housing, environmental and social-justice communities.

(RNM) Regional Network Management

RNM looks at the entire transit system as a whole, including fares, schedules, network connectivity, operations, budgets and more. MTC is working to identify ways to improve the network and rider experience.

(RTEP) Regional Transit Expansion Program

An identified list of high-priority rail and express/rapid bus improvements to serve the Bay Area’s most congested corridors. The program was adopted in December 2001 pursuant to MTC Resolution 3434 to establish clear priorities for the investment of transit expansion funds over the next decade.

Return to Source

A requirement with some funding programs (such as TDA) that the money flow back to the county where it originated from tax revenues, regardless of need.

(RTIP) Regional Transportation Improvement Program

The Regional Transportation Improvement Program is a listing of highway, local road, transit and bicycle projects that the region hopes to fund; compiled by MTC every two years from priority lists submitted by local jurisdictions. The California Transportation Commission (CTC) must either approve or reject the RTIP in its entirety. Once the CTC approves an RTIP, it is combined with those from other regions to comprise 75% of the funds in the State Transportation Improvement Program or STIP. (Also see "[CTC] California Transportation Commission" and “STIP.”)

(RTP) Regional Transportation Plan

A master plan to guide the region’s transportation investments for at least a 20-year period. Typically updated every four years, it is based on projections of growth in population and jobs and the ensuing travel demand. Required by state and federal law, it includes programs to better maintain, operate and expand transportation. The Bay Area’s current long-range transportation plan and sustainable communities strategy is known as Plan Bay Area 2050.

(SAFE) Service Authority for Freeways and Expressways

As the region’s SAFE, MTC, in partnership with the California Highway Patrol and the California Department of Transportation, manages the Bay Area’s fleet of Freeway Service Patrol tow trucks and roadside call boxes. State legislation in 1987 created the MTC SAFE to reduce congestion, improve public safety and enhance air quality by quickly identifying, responding to, and clearing freeway incidents. Services are funded in part through a $1 surcharge on motor vehicle registrations.

Sales Tax Authority

An agency that administers a voter-approved county transportation sales tax program; in most Bay Area counties, the county transportation agency or county also serves as the sales tax authority.

SB 375

This 2008 law is designed to complement AB 32 and includes two main statutory requirements: to reduce per-capita carbon dioxide (CO2) emissions from cars and light duty trucks, and to house 100% of the region’s projected 25-year population growth, regardless of income level.

(SCS) Sustainable Communities Strategy

Under SB 375, each of California's metropolitan regions must prepare a “sustainable communities strategy” (SCS) as an integral part of its regional transportation plan (RTP). The SCS contains land use, housing, and transportation strategies that, if implemented, would enable the region to meet its greenhouse gas emission reduction targets set by the state. See also Plan Bay Area.

Self-Help Counties

A term used to describe counties that have enacted local voter-approved funding mechanisms — such as half-cent sales taxes — to pay for transportation improvements. In the Bay Area, eight counties have passed such measures: Alameda, Contra Costa, Marin, Napa, San Francisco, San Mateo, Santa Clara and Sonoma.

Smart Growth

A set of policies and programs designed to protect, preserve and economically stimulate established communities, while protecting valuable natural and cultural resources and limiting sprawl.

(SOV) Single-Occupant Vehicle

A vehicle with one occupant, the driver, who is sometimes referred to as a “drive alone.”

(STA) State Transit Assistance

A state program that provides funding for mass transit operations and capital projects.

(STIP) State Transportation Improvement Program

What the California Transportation Commission (CTC) ends up with after combining various RTIPs, as well as a list of specific projects proposed by Caltrans. Covering a five-year span and updated every two years, the STIP determines when and if transportation projects will be funded by the state. Projects included in the STIP must be consistent with the long-range transportation plan.

(STP) Surface Transportation Program

One of the key federal funding programs; STP money is “flexible,” meaning it can be spent on mass transit, pedestrian and bicycle facilities, as well as on roads and highways.

Transportation Control Measure

A strategy to reduce driving or to smooth traffic flows in order to cut auto emissions and resulting air pollution. Examples of TCMs include carpool lanes, roving tow truck patrols to clear stalls and accidents from congested roadways, new or increased transit service, and ridesharing services to get people into carpools and vanpools.

(TDA) Transportation Development Act

State law enacted in 1971. TDA funds are generated from a tax of one-quarter of one percent on all retail sales in each county; used for transit, special transit for disabled persons, and bicycle and pedestrian purposes. TDA money is collected by the state and allocated in the Bay Area by MTC to fund transit operations and programs. In non-urban areas, TDA funds may be used for streets and roads under certain conditions.

Title VI

Refers to Title VI of the Federal Civil Rights Act of 1964, and requires that transportation planning and programming be nondiscriminatory on the basis of race, color or national origin. Integral to Title VI is the concept of environmental justice. (Also see “Environmental Justice.”)

(TIP) Transportation Improvement Program

A short-term (covering three years) program of transportation projects that will be funded with all federal funds expected to flow to the region; the TIP also lists regionally significant projects funded with state or local dollars. The projects contained in the TIP are drawn from, and consistent with, the long-range transportation plan.

(TOC) Transit-Oriented Communities

Transit-oriented communities (TOCs) feature housing and business development that is near to transportation, putting public transit in reach for more people and improving the quality of life in the Bay Area.

This type of development helps reduce sprawl, traffic congestion and air pollution. Transit-oriented communities include housing, jobs and community amenities located near to high-quality public transportation.

(TOD) Transit-Oriented Development

A type of development that links land use and transit facilities to support the transit system and help reduce sprawl, traffic congestion and air pollution. Transit-oriented development includes housing, along with complementary public uses (jobs, retail and services), located at a strategic point along a regional transit system, such as a rail hub. MTC replaced the TOD Policy with the Transit-Oriented Communities (TOC) Policy.

(TDM) Transportation Demand Management

Transportation demand management (TDM) refers to a set of strategies aimed at reducing the demand for roadway travel, particularly in single occupancy vehicles. MTC’s Climate Initiatives Program uses parking pricing and other strategies to reduce demand for roadway space in select locations and/or at select times.

Transit 2050+

Transit 2050+ is the transportation element within Plan Bay Area 2050+. As the Bay Area continues to face financial challenges from the COVID-19 pandemic, Transit 2050+ will focus on prioritizing revisions to the six transit-related strategies from the current long-range transportation plan, Plan Bay Area 2050. 

Travel Demand Model

Used by transportation planners for simulating current travel conditions and for forecasting future travel patterns and conditions. Models help planners and policy-makers analyze the effectiveness and efficiency of alternative transportation investments in terms of mobility, accessibility, and environmental and equity impacts.

Tribal Government Consultation

A formal process between MPOs and federally recognized Indian tribes, which are recognized as sovereign nations, that calls for government-to-government consultation regarding transportation planning and programming efforts.

Uncommitted Revenues

Anticipated transportation revenues available for new investments after accounting for revenue committed by law, ballot measure or MTC programming actions. These revenues account for about 10 percent of all revenues forecasted to be available over the 25-year period of the regional transportation plan, and are the major focus of the update process. (Also see “Committed Revenues.”)

(U.S. DOT) United States Department of Transportation

The federal cabinet-level agency with responsibility for highways, mass transit, aviation and ports; it is headed by the Secretary of Transportation. The DOT includes the Federal Highway Administration and the Federal Transit Administration, among others. There also are state DOTs (known in California as Caltrans).

Value Pricing

The concept of assessing higher prices for using certain transportation facilities during the most congested times of the day, in the same way that airlines offer off-peak discounts and hotel rooms cost more during prime tourist seasons. Also known as congestion pricing and peak-period pricing, examples of this concept include higher bridge tolls during peak periods or charging single-occupant vehicles that want to use carpool lanes.

(VMT) Vehicle Miles Traveled

One vehicle (whether a car carrying one passenger or a bus carrying 30 people) traveling one mile constitutes a vehicle mile. VMT is one measure of the use of Bay Area freeways and roads.