| Abbreviation | Definition |
|---|---|
| RMIX | Ready Mix Concrete Company |
| RMJ | Rail Model Journal |
| RMLU | Royal Mail Lines Limited |
| RMMX | Railcar Limited |
| RMPX | Progress Rail Services Corporation (Railcar Ltd) |
| RMPZ | TAL International |
| RMPZ | Transamerica Leasing Incorporated |
| RMQ | Railway Museum Quarterly |
| RMRA | Rocky Mountain Rail Authority |
| RMRG | Rapid Metro Rail Gurgaon |
| RMRR | Rocky Mountain Railcar and Railroad |
| RMRR | Rocky Mountain Railcar and Railroad Incorporated |
| RMRX | Rocky Mountaineer |
| RMS | Rail Management Services |
| RMSP | Rail Motor Stopping Place |
| RMSX | Harsco Track Technologies |
| RMSX | Pandrol Jackson Incorporated |
| RMT | Rail Maritime and Transport |
| RNDX | ACF Industries |
| RNDX | ACF Industries Incorporated, Amcar Division |