A
| AA | Automobile Association |
| AAA | American Automobile Association |
| AACC | Autonomous Adaptive Cruise Control |
| AAMA | American Automobile Manufacturers Association |
| AAMVA | American Association of Motor Vehicle Administrators |
| AAR | Association of American Railroads |
| AASHTO | American Association of State Highway and Transportation Officials |
| AATMS | Airborne Air Traffic Management System |
| ABI | Allied Business Intelligence |
| ABS | Anti-lock Braking System |
| AC ASSIST/ | Anti-Collision Autonomous Support, Safety and Intervention SysTem |
| (ROADSTER) | |
| ACC | Adaptive Cruise Control |
| ACCEPT | ALERT Concerted Co-operation in European Pilots for TMC |
| ACE | Advanced Communication Experiments |
| ACS | Automated (Automatic) Clearance Sensing |
| ADA | Americans with Disabilities Act |
| ADAC | Allgemeiner Deutscher AutomobileClub |
| ADEPT | Automatic Debiting and Electronic Payments for Transport |
| ADEPT II | Automatic Debiting and Electronic Payments for Transport |
| ADIS | Advanced Driver Information Systems |
| ADS | Automatic Debiting Systems |
| ADVANCE | Advanced Driver and Vehicle Advisory Navigation ConcEpt |
| ADVISE | ADditional Vehicle interactive Information SErvice |
| AEDIC | Advanced Easy Driving and Informatic Car |
| AEI | Automatic Equipment Identification |
| AF | Audio Frequency |
| AFC | Automatic Fare (Fee) Collection |
| AFCAC | Automatic Fee Collection and Access Control |
| AG | Automated Guideway |
| AGC | Automatic Gain Control |
| AGE | Automatische Gebührenerhebung auf autobahnen |
| AGT | Automatic Guideway Transit |
| AH | Automated Highway |
| AHAR | Automatic (Advanced) Highway Advisory Radio |
| AHC | Automatic (Advanced) Highway Chauffeuring |
| AHMT | Advanced Highway Maintenance Technology |
| AHS | Automated (Advanced) Highway System |
| AHSS | Automated Highway Safety Systems |
| AHV | Autonomous Highway Vehicle |
| AI | Artificial Intelligence |
| AIAM | Association of International Automobile Manufactures, Inc. |
| AIBS | Automated Identification and Billing System |
| AICC | Autonomous Intelligent Cruise Control |
| AID | Automatic Incident Detection |
| AIP | Accident Investigation and Prevention |
| AIRPORT-G | (Airport Integrated Research and development Project for Operational regulation) |
| AIST | Agency of Industrial Science and Technology |
| AIT | Alliance Internationale d’Tourisme |
| ALERT | Advice and problem Location for European Road Traffic |
| ALI | Autofahrer Leit und Informations system |
| ALI-SCOUT | ALI, auto-SCOUT |
| ALV | Autonomous Land Vehicle |
| AM | Amplitude Modulation |
| AMIS | Advanced Mobile Information System |
| AMTA | American Mobile Telecommunications Association |
| AMTICS | Advanced Mobile Traffic Information and Communication Systems |
| ANIMATE | Added kNow-how In Management of TElematics |
| ANSA | AN open Systems Architecture |
| ANSI | American National Standards Institute, Inc. |
| ANTRARES | A New Traffic Approach Regarding Energy Saving |
| ANTTS | Automatic Network Travel Time System |
| AP | Administrative Processes |
| APC | Automated Passenger Counting |
| APD | Avalanche Photo Diode |
| API | Application Programming Interface |
| API | American Petroleum Institute |
| APIS | Advanced Parking Information System |
| APLC | Advanced Programming Logic Circuit |
| APMDU | the Association for the Promotion of Millimeter-wave Development and Utilization |
| APPLE | Advanced Pilot Project for London and Europe |
| APS | Auto Pilot System |
| APTA | American Public Transit Association |
| APTS | Advanced Public Transportation Systems |
| AQTR | Association Québécoise du Transport et des Routes inc. |
| ARCS | Automatic Route Control System |
| ARGOS | (Investigation into driver behavior) |
| ARI | Autofahrer Rundfunk Information |
| ARIADNE | Application of a Real-time Intelligent Aid for Driving and Navigation Enhancement |
| ARIAM | ARI+aufgrund Aktueller Meßdaten |
| ARIAM | (Advanced version of ARI) |
| ARIB | Association of Radio Industries and Business |
| ARIES | Automobiles’ Roadside-transceiver Infrastructure for Extensive Service |
| ARISE | Automobile Road Information System Evolution |
| ARPA | Advanced Research Projects Agency |
| ARQ | Automatic Repeat reQuest |
| ARSI | Automated Roadside Safety Inspection for commercial vehicles |
| ARTBA | American Road and Transportation Builders Association |
| ARTHUR | Automatic Radio communication system for Traffic emergency situations on Highways an Urban Roads |
| ARTIC | Advanced Rural Transportation Information and Coordination |
| ARTICS | Advanced Road Transport Informatic and Control System |
| ARTIS | Advanced Road Transport Informatics in Spain |
| ARTS | Advanced Rural Transportation Systems |
| ARTS | Advanced Road Traffic Systems |
| ARTT | Advanced Road Transport Telematics |
| ARV | Autonomous Road Vehicle |
| ASA | American Statistical Association |
| ASCE | American Society of Civil Engineers |
| ASCII | American Standard Code for Information Interchange |
| ASD | Automated Systems Development |
| ASECAP | ASsociation Européens des Concessionaires d’Autoroutes et d’ouvrages á Péage |
| ASETA | (Associación de Sociedades Españolas Concesionarias de Autopistas, Túneles) |
| (Association of Spanish motorway Toll Authorities) | |
| ASG | Automotive Sciences Group |
| ASIC | Application Specific Integrated Circuit |
| ASII | Advanced Systems Integration and Implementation |
| ASK | Amplitude Shift Keying |
| ASME | American Society of Mechanical Engineers |
| ASN.1 | Abstract Syntax Notation One |
| ASSIST | (Driving support) |
| ASTERIX | (System and Scenario Simulation for Testing RTI Systems) |
| ASTM | American Society of Testing and Materials |
| ASTRA | integrated system of Assistance Services for TRAvel and traffic |
| ASV | Advanced Safety Vehicle |
| ATA | American Trucking Associations |
| ATA | Associazione Tecnica dell’ Automobile |
| ATC | Advanced Traffic Controller |
| ATC | Area Traffic Control |
| ATC | Automated (electronic) Toll Collection |
| ATCC | Area Traffic Control Centers |
| ATEC | Association pour le development de techniques de Transport d’Environment et de Circulation |
| ARES | Advanced Transport Efficiency System |
| ATHOS | Airport Tower Harmonization cOntroller System |
| ATICS | Automobile Traffic Information and Control System |
| ATIS | Alliance international Tourism Information System |
| ATIS | Advanced Traveler Information Systems |
| ATIS | Advanced Traffic Information Service |
| ATIS | Advanced Travelers Information Systems |
| ATiS | Advanced Traffic information Service |
| ATLAS | Acquisition par Télédiffusion de Logiciels Automobiles pour les Services |
| ATM | Asynchronous Transfer Mode |
| ATMIS | Advanced Transportation Management & Information System |
| ATMS | Advanced Traffic Management System |
| ATR | Alliance for Transportation Research |
| ATRP | Automatic Tolls and Road Pricing |
| ATSAC | Automated Traffic Surveillance And Control |
| ATSSA | American Traffic Safety Services Association |
| ATT | Advanced Transport Telematics |
| ATT-ALERT | Advanced Transport Telematics – Advice and problem Location for European Road Traffic |
| ATTAIN | Applicability in Transport and Traffic of Artificial INtelligence |
| AUSCI | Adaptive Urban Signal Control and Integration |
| AUSIAS | ATT in Urban Sites with Integration And Standardization |
| Autoguide | (Interactive Dynamic Route Guidance and Information System) |
| AUTOPOLIS | AUTOmatic POLicing Information Systems |
| Autoscope TM | (A system that uses a video camera and computer soft developed by University of Minnesota.) |
| AUVS | Association of (Autonomous) Unmanned Vehicle Systems |
| AVASD | Advanced Vehicle & Automated Systems Development |
| AVC | Automated Vehicle Classification |
| AVCCS | Advanced Vehicle Command & Control Systems |
| AVCS | Advanced (Automatic) Vehicle Control System |
| AVD | Advanced Vehicle Development |
| AVHS | Advanced Vehicle Highway System |
| AVHT | Advanced Vehicle and Highway Technologies |
| AVI | Automatic (Automatedz) Vehicle Identification |
| AVIC | Audio-Visual Information Commmication-1 |
| AVL | Automatic (Automated) Vehicle Location |
| AVLS | Automatic Vehicle Location System |
| AVM | Automatic Vehicle Monitoring |
| AVMC | Advanced Vehicle Monitoring and Control |
| AVN | Automatic Vehicle Navigation |