| AC | Alternating Current |
| AIW | Amey Infrastructure Wales |
| ASLEF | The Associated Society of Locomotive Engineers and Firemen |
| AT | Active Travel |
| AV | Autonomous Vehicle |
| BCR | Benefits Costs Ratio |
| BR | British Rail |
| BRT | Bus Rapid Transit |
| BSSG | Bus Service Support Grant |
| BTM | Bristol Temple Meads |
| BUA | Built Up Area (ONS) |
| CAA | Civil Aviation Authority |
| CAPEX | Capital Expenditure |
| CASR | Cardiff Area Signalling and Renewals |
| CBDC | Cardiff Bay Development Corporation |
| CBP | Cardiff Business Partnership |
| CCC | Cardiff County Council |
| CCCm | Climate Change Committee |
| CCR | Cardiff Capital Region |
| CEO | Chief Executive Officer |
| CJC | Corporate Joint Committee |
| COO | Chief Operating Officer |
| CP | Control Period |
| CRA | Country and Regional Analysis (HMT) |
| CU | Cardiff University |
| CVL | Core Valley Lines |
| DC | Direct Current |
| DCFW | Design Commission for Wales |
| DfT | Department for Transport |
| DM | Deputy Minister |
| DMU | Diesel Multiple Unit |
| DOO | Driver Only Operation |
| DRT | Demand Responsive Transit |
| ECML | East Coast Mainline |
| EFTA | European Free Trade Association |
| EMU | Electric Multiple Unit |
| ERDF | European Regional Development Fund |
| EV | Electric Vehicle |
| FBC | Full Business Case |
| FM | First Minister |
| GDHI | Gross Domestic Household Income |
| GDP | Gross Domestic Product |
| GEOPL | School of Geography and Planning |
| GVA | Gross Value Add |
| GWEP | Great Western Electrification Programme |
| GWML | Great Western Mainline |
| GWP | Great Western Partnership |
| HMT | Her Majesty’s Treasury |
| HoW | Heart of Wales Line |
| HR | Heavy Rail |
| HS2 | High Speed 2 |
| HSR | High Speed Rail |
| IRP | Integrated Rail Plan |
| IWA | Institute of Welsh Affairs |
| JLL | Jones Lang LaSalle |
| KA | Keolis Amey |
| KPI | Key Performance Indicator |
| LA | Local Authority |
| LGA | Lloyd George Avenue |
| LoS | Line of Sight |
| LR | Light Rail |
| LR | Long Run (Induced Demand) |
| LRT | Light Rail Transit |
| LRV | Light Rail Vehicle |
| LSOA | Lower Super Output Area |
| LUF | Levelling Up Funding |
| MD | Managing Director |
| MP | Member of Parliament |
| MS | Member of The Senedd |
| MV | Metro Vehicle (another name for the new TfW Stadler tram-trains) |
| NPR | Northern Powerhouse Rail |
| NR | Network Rail |
| NWML | North Wales Mainline |
| NWTC | North Wales Transport Commission |
| NZW | Net Zero Wales |
| OBC | Outline Business Case |
| OLE | Overhead Line Electrification |
| OMR | Operations Maintenance and Renewals |
| ONS | Office for National Statistics |
| ORR | Office for Road and Rail |
| OPEX | Operating expenditure |
| P&R | Park and Ride |
| PAX | Passenger Numbers |
| PAYG | Pay as You Go |
| PFI | Private Finance Initiative |
| PRM | Persons of Reduced Mobility |
| PSOC | Programme Strategic Outline Case |
| PT | Public Transport |
| PTA | Passenger Transport Authority |
| PTE | Passenger Transport Executive |
| RAB | Regulatory Asset Base |
| RCT | Rhondda Cynon Taf |
| RL | Rhymney Line |
| RNEP | Rail Network Enhancement Pipeline (Network Rail) |
| ROGs | Railways & Other Guided Transport Systems (Safety) Regulations |
| RTA | Road Traffic Accident |
| RTP | Regional Transport Plan |
| RUC | Road User Charge |
| RYR | Restoring Your Railway |
| SACTRA | Standing Advisory Committee on Trunk Road Appraisal |
| SCCEI | Senedd Climate Change, Environment & Infrastructure Committee |
| SDG | Steer Davies Gleave |
| SDL | Swansea District Line |
| SDP | Strategic Development Plan |
| SDPM | Strategic Development Programme Manager |
| SEWEF | Southeast Wales Economic Forum |
| SEWTA | Southeast Wales Transport Alliance |
| SEWTC | Southeast Wales Transport Commission |
| SNTB | Sub National Transport Body |
| SOC | Strategic Outline Case |
| SR | Short Run (Induced Demand) |
| SRA | Strategic Rail Authority |
| SWIFT | South Wales Integrated Fast Transit |
| SWML | South Wales Mainline |
| T&Cs | Terms and Conditions |
| TAG | Transport Appraisal Guidelines |
| TAM | Treherbert, Aberdare, Merthyr Lines |
| TCS | Tram Control System |
| TfW | Transport for Wales |
| TIGER | Transport Integration in the Gwent Economic Region |
| ToC | Train Operating Company |
| TOD | Transit Oriented Development |
| TRU | Trans Pennine Route Upgrade |
| TTWA | Travel to Work Area |
| TWAO | Transport Work Act Order |
| UCR | Union Connectivity Review |
| VfM | Value for Money |
| VLE | Valley Line Electrification |
| VoG | Vale of Glamorgan |
| W&B | Wales and Borders |
| WCML | West Coast Mainline |
| WDA | Welsh Development Agency |
| WebTAG | Web based Transport Analysis Guidance (DfT) |
| WEFO | Welsh European Funding Office |
| WEB | Wider Economic Benefits |
| WEI | Wider Economic Impacts |
| WelTAG | Welsh Transport Appraisal Guidelines |
| WG | Welsh Government |
| WIMD | Welsh Index of Multiple Deprivation |
| WLGA | Welsh Local Government Association |
| WRU | Welsh Rugby Union |
| WTS | Wales Transport Strategy (Llwybr Newydd) |
