| AADT | average annual daily traffic |
| AADTT | average annual daily truck traffic |
| AARP | American Association of Retired Persons |
| AASHTO | American Association of State Highway and Transportation Officials |
| ACE | Altamont Commuter Express |
| ACS | American Community Survey |
| AC Transit | Alameda-Contra Costa Transit District |
| ADA | Americans with Disabilities Act of 1990 |
| ADT | annual daily traffic; average daily traffic |
| ADTT | average daily truck travel |
| AEO | Annual Energy Outlook |
| APTA | American Public Transportation Association |
| APU | auxiliary power unit |
| ATDM | active transportation and demand management |
| ATM | Active Traffic Management |
| ATS | alternative transportation systems |
| BAB | Build America Bond |
| BAC | blood alcohol content |
| BART | San Francisco Bay Area Rapid Transit District |
| Bay Area | San Francisco Bay Area |
| B/C | benefit-cost |
| BCR | benefit-cost ratio |
| BIRM | Bridge Inspector's Reference Manual |
| BLM | Bureau of Land Management |
| BPI | Bid Price Index |
| C-TIP | Cross-Town Improvement Project |
| C&P | Conditions and Performance |
| CAFE | Corporate Average Fuel Economy |
| CARB | California Air Resources Board |
| CATA | Central Arkansas Transit Authority |
| CATS | Charlotte Area Transit System |
| CDOT | Connecticut Department of Transportation |
| CFR | U.S. Code of Federal Regulations |
| CFS | Commodity Flow Survey |
| CMAQ | Congestion Mitigation and Air Quality |
| CM-GC | construction manager-general contractor |
| CMTA | Capital Metropolitan Transportation Authority |
| CNG | compressed natural gas |
| CO2 | carbon dioxide |
| Combo | combination (trucks) |
| CPI | Consumer Price Index |
| CRR | Corps Recreation Roads |
| CTA | Chicago Transit Authority |
| CTE | Center for Transportation and the Environment |
| DART | Dallas Area Rapid Transit |
| DB | design-build |
| DBB | design-bid-build |
| DC | direct current |
| DHS | Department of Homeland Security |
| DO | directly operated |
| DOD | Department of Defense |
| DOE | Department of Energy |
| DOI | Department of the Interior |
| DOT | Department of Transportation |
| DR | Demand Response |
| DRM | directional route mile |
| DTS | City and County of Honolulu Department of Transportation Services |
| EDC | Every Day Counts |
| EERE | Efficiency and Renewable Energy |
| EIA | Energy Information Administration |
| EPA | Environmental Protection Agency |
| FAF | Freight Analysis Framework |
| FARS | Fatality Analysis Reporting System |
| FCEB | fuel cell electric bus |
| FH | Forest Highways |
| FHWA | Federal Highway Administration |
| FLH | Office of Federal Lands Highway |
| FLHP | Federal Lands Highway Program |
| FLMA | Federal Land Management Agency |
| FMCSA | Federal Motor Carrier Safety Administration |
| FPM | freight performance measures |
| FS | USDA Forest Service |
| FTA | Federal Transit Administration |
| FWS | Fish and Wildlife Service |
| FY | fiscal year |
| g/dL | gram per deciliter |
| GARVEE | Grant Anticipation Revenue Vehicle |
| GCRTA | The Greater Cleveland Regional Transit Authority |
| GDP | gross domestic product |
| GHG | greenhouse gas |
| GIS | geographic information system |
| GPS | global positioning system |
| GRS-IBS | geosynthetic reinforced soil integrated bridge system |
| HART | Hillsborough Area Regional Transit Authority |
| HBP | Highway Bridge Program |
| HERS | Highway Economic Requirements System |
| HERS-ST | HERS State Version |
| HFCS | Highway Functional Classification System |
| HPMS | Highway Performance Monitoring System |
| HPMS-AP | HPMS Analytical Process |
| HR | Heavy Rail |
| HSIP | Highway Safety Improvement Program |
| HTF | Highway Trust Fund |
| HUD | Department of Housing and Urban Development |
| IC | intelligent compaction |
| IDAS | ITS Deployment Analysis System |
| INVEST | Infrastructure Voluntary Evaluation Sustainability Tool |
| IRI | International Roughness Index |
| IRR | Indian Reservation Roads |
| ISIP | Intersection Safety Implementation Plan |
| ISTEA | Intermodal Surface Transportation Efficiency Act of 1991 |
| IT | Island Transit |
| ITS | intelligent transportation system(s) |
| King County Metro | King County Department of Transportation |
| KT | Kenosha Transit |
| LACMTA | Los Angeles County Metropolitan Transportation Authority |
| LNG | liquefied natural gas |
| LR | Light Rail |
| LPG | liquefied petroleum gas |
| MAP-21 | Moving Ahead for Progress in the 21st Century Act |
| MARTA | Metropolitan Atlanta Rapid Transit Authority |
| MATA | Memphis Area Transit Authority |
| MB | Motorbus |
| MBTA | Massachusetts Bay Transportation Authority |
| MDT | Miami-Dade Transit |
| ME-PDG | Mechanistic Empirical Pavement Design Guide |
| Metra | Northeast Illinois Regional Commuter Railroad Corporation |
| METRO | Bi-State Development Agency; Metropolitan Transit Authority of Harris County, Texas |
| Metrolink | Southern California Regional Rail Authority |
| MIR | Military Installation Roads |
| MOU | Memorandum of Understanding |
| MOVES | Motor Vehicle Emission Simulator |
| mpg | miles per gallon |
| MPO | metropolitan planning organization |
| MR&R | maintenance, repair, and replacement; maintenance, repair, and rehabilitation |
| MSA | Metropolitan Statistical Area |
| MTA | Mass Transit Account; Maryland Transit Administration |
| MTA LIRR | MTA Long Island Rail Road |
| MTA-MNCR | Metro-North Commuter Railroad Company |
| MTS | San Diego Metropolitan Transit System |
| MTSI | mean time to service interruption |
| MUNI | San Francisco Municipal Railway |
| MUTCD | Manual of Uniform Traffic Control Devices |
| NAVC | Northeast Advanced Vehicle Consortium |
| NASS GES | National Automotive Sampling System General Estimates System |
| NBER | National Bureau of Economic Research |
| NBI | National Bridge Inventory |
| NBIAS | National Bridge Investment Analysis System |
| NBIS | National Bridge Inspection Standards |
| NCHRP | National Cooperative Highway Research Program |
| NCTD | North County Transit District |
| NEPA | National Environmental Policy Act |
| NFS | National Forest System |
| NFSR | National Forest System Roads |
| NFCBP | National Fuel Cell Bus Program |
| NFT Metro | Niagara Frontier Transportation Authority |
| NHCCI | National Highway Construction Cost Index |
| NHPP | National Highway Performance Program |
| NHS | National Highway System |
| NHTS | National Household Travel Survey |
| NHTSA | National Highway Traffic Safety Administration |
| NICTD | Northern Indiana Commuter Transportation District |
| NJ TRANSIT | New Jersey Transit Corporation |
| NLCS | National Landscape Conservation System |
| NNEPRA | Northern New England Passenger Rail Authority |
| NOx | nitrogen oxide |
| NORTA | New Orleans Regional Transit Authority |
| NPS | National Park Service |
| NTD | National Transit Database |
| NTPP | Nonmotorized Transportation Pilot Program |
| NWRS | National Wildlife Refuge System |
| NYCT | MTA New York City Transit |
| O&M | operations and maintenance |
| OF&E | Other Freeway and Expressway |
| OMB | Office of Management and Budget |
| OPA | Other Principal Arterial |
| P3 | Public-Private Partnership |
| PAB | Private Activity Bond |
| PATCO | Port Authority Transit Corporation |
| PATH | Port Authority Trans-Hudson Corporation |
| PCJPB | Peninsula Corridor Joint Powers Board |
| PEL | Planning and Environmental Linkages |
| PENNDOT | Pennsylvania Department of Transportation |
| PLDR&T | public lands development roads and trails |
| PLHD | Public Lands Highway Discretionary Program |
| PM-10 | particulate matter of 10 microns in diameter or smaller |
| PMT | passenger miles traveled; person miles of travel |
| Port Authority | Port Authority of Allegheny County |
| PRHTA | Puerto Rico Highway and Transportation Authority |
| PRP | park roads and parkways |
| PSR | Present Serviceability Rating; Pavement Serviceability Rating |
| PT | purchased transportation |
| PV | passenger vehicle |
| RAIRS | Rail Accident/Injury Reporting System |
| Reclamation | Bureau of Reclamation |
| Recovery Act | American Recovery and Reinvestment Act |
| RMRTD | Rio Metro Regional Transit District |
| RR | Refuge Roads |
| RSDP | Roadway Safety Data Program |
| RTA | Regional Transportation Authority |
| RTD | Denver Regional Transportation District |
| RVD | recreation visitor days |
| Sacramento RT | Sacramento Regional Transit District |
| SAFETEA-LU | Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users |
| SEPTA | Southeastern Pennsylvania Transportation Authority |
| SGR | state of good repair |
| SHRP2 | Strategic Highway Research Program 2 |
| SHSP | Strategic Highway Safety Plan |
| SIB | State Infrastructure Bank |
| SIRTOA | Staten Island Rapid Transit Operating Authority |
| SQC | Synthesis, Quantity, and Condition |
| SRTS | Safe Routes to School |
| S/TIP | State/Transportation Improvement Program |
| ST | Central Puget Sound Regional Transit Authority |
| STAA | Surface Transportation Assistance Act of 1982 |
| STP | Surface Transportation Program |
| STRAHNET | Strategic Highway Network |
| STURAA | Surface Transportation and Uniform Relocation Assistance Act of 1987 |
| SU | single-unit (truck) |
| TEA-21 | Transportation Equity Act for the 21st Century |
| TEAM | Transit Electronic Award Management |
| TERM | Transit Economic Requirements Model |
| TEU | Twenty-foot equivalent unit |
| TIFIA | Transportation Infrastructure and Finance Innovation Act |
| TIGER | Transportation Investment Generating Economic Recovery |
| TMC | traffic management center |
| TMG | Traffic Monitoring Guide |
| TRB | Transportation Research Board |
| TRDF | Texas Research and Development Foundation |
| TriMet | Tri-County Metropolitan Transportation District of Oregon |
| TRIP | Transit in the Parks |
| TRI-Rail | South Florida Regional Transportation Authority |
| TTI | Texas Transportation Institute |
| TVT | Traffic Volume Trends |
| UCR | Urban Congestion Report |
| UN | United Nations |
| UPT | unlinked passenger trips |
| U.S. | United States |
| USACE | U.S. Army Corps of Engineers |
| USAGE | United States Applied General Equilibrium |
| U.S.C. | United States Code |
| USDA | U.S. Department of Agriculture |
| USFS | U.S. Forest Service |
| UTA | Utah Transit Authority |
| UZA | urbanized area |
| VII | Vehicle Infrastructure Integration |
| VIUS | Vehicle Inventory and Use Survey |
| VMR | Valley Metro Rail, Inc. |
| VMS | variable message signs |
| VMT | vehicle miles traveled |
| VRE | Virginia Railway Express |
| VRM | vehicle revenue mile |
| V/SF | volume/service flow |
| VSL | value of a statistical life; variable speed limit |
| VTA | Santa Clara Valley Transportation Authority |
| VTTS | value of travel time savings |
| WMA | warm mix asphalt |
| WMATA | Washington Metropolitan Area Transit Authority |
| WSDOT | Washington Department of Transportation |
| ZEBA | Zero Emission Bay Area |
