| ABCL | Automatic Barrier Level Crossing Locally Monitored by train crew |
| AHB | Automatic Half Barrier - type of level crossing |
| AOCL | Automatic Open (level) Crossing Locally monitored |
| ASR | Abellio ScotRail |
| ATOC | Association of Train Operating Companies |
| BCR | Benefit/cost ratio. The financial benefit from every £1 of public investment |
| CET | Controlled-Emission Toilet |
| CP6 | The 2019-24 investment period |
| CTC | Centralised Traffic Control |
| DDA | Disability Discrimination Act |
| DfT | Department for Transport (England & Wales) |
| DRS | Direct Rail Services, a freight operating company |
| EARL | Edinburgh Airport Rail Link |
| ECML | East Coast Main Line |
| ECS | Empty Coaching Stock |
| ERTMS | European Rail Traffic Management System - works with signals in the cab rather than at the lineside |
| FNL | Far North Line |
| FOC | Freight operating company |
| FSR | First ScotRail |
| GARL | Glasgow Airport Rail Link |
| GBRf | G B Railfreight Ltd, a FOC |
| GPS | Global Positioning System |
| GRIP | Guide to Railway Investment Projects. Network Rail investment process |
| GSM-R | Global systems for mobile communication - railway |
| HITRANS | Highlands and Islands Transport Partnership (our local RTP) |
| HLOS | High Level Output Specification |
| HML | Highland Main Line (Perth to Inverness) |
| HMRI | Her Majesty's Railway Inspectorate - transferred from H&SE to ORR |
| HRP | former Highland Rail Partnership |
| H&SE | Health & Safety Executive |
| HST | High Speed Train |
| HS2 | Proposed high speed line from London to Scotland |
| InvAb | Inverness-Aberdeen line |
| KPI | Key Performance Indicator |
| LD | Light diesel |
| LX | Level crossing |
| MAS | Multiple Aspect Signal |
| NR | Network Rail. Responsible for track, signalling and stations |
| ORR | Office of Rail Regulation |
| PAX | Passengers |
| PF | Passenger Focus (the replacement for RPC) |
| PNB | Personal Needs Break |
| PPM | Public Performance Measure. Measures train punctuality and reliability |
| PSI | Points set indicator |
| RA5 | Route Availability. Track strength measure |
| RAB | Regulated Asset base |
| RAIB | Rail Accident Investigation Board |
| RDW | Rest day working |
| R4G or RfG | Room for Growth (Scott Wilson Report) |
| RETB | Radio Electronic Token Block (signalling method used on FNL) |
| RIAC | Rail Industry Advisory Committee |
| ROGS | Railways and other Guided Systems (Safety) |
| ROSCO | Rolling Stock Owning Company |
| RPC | Rail Passengers Council (or Committee) |
| RPCS | Rail Passengers Committee for Scotland |
| RSSB | Rail Safety and Standards Board |
| RTP | Regional Transport Partnership |
| RTS | Regional Transport Strategy |
| RUG | Rail User Group |
| RUS | Route Utilisation Strategy (Network Rail's planning document) |
| RVAR | Rail Vehicle Accessibility Regulations |
| S&C | Switches and Crossings. Track pointwork |
| SDO | Selected Door Operation |
| SLU | Standard Length Unit (6 metres or 21 feet) measures whether trains can fit in to loops and sidings |
| SoFA | Statement of Funds Available |
| SRT | Sectional Running Time |
| SQUIRE | Service Quality Incentive Regime administered by Transport Scotland with powers to fine ROSCOs for poor standards |
| SRA | Strategic Rail Authority |
| STAG | Scottish Transport Appraisal Guidance. Measures affordability of new projects |
| STPR | Strategic Transport Projects Review. December 2008 priorities |
| TEE | Transport Economic Efficiency. Evaluation tool for projects |
| TEN | Trans-European Network System |
| Tier 3 | A project development fund |
| TOC | Train Operating Company |
| TPWS | Train Protection and Warning System |
| TRUST | Computer system which gives a record of actual train running |
| TS | Transport Scotland |
| WCML | West Coast Main Line |
| WHL | West Highland Line |
| 158 | Express Sprinter units used on Far North Line |
| 170 | Turbostar units used on HML |