| Abbreviation | Definition |
|---|---|
| RRIX | Rader Railcar II Incorporated |
| RRLGP | Rail Revolving Loan and Grant Program (Iowa) |
| RRLX | Railroad Resources |
| RRMX | RRM Properties |
| RRP | Regional Rail Partners |
| RRPX | Railroad Power Leasing |
| RRRR | Rock & Rail Inc. |
| RRRR | Rock and Rail Incorporated |
| RRRX | Rex Leasing |
| RRRX | Rex Leasing Incorporated |
| RRTP | Railway Rehabilitation Track Programme |
| RRV | Road Rail Vehicle |
| RRVW | Red River Valley and Western Railroad |
| RS | Rail Schedule |
| RS | Roberval and Saguenay Railway |
| RS | Roberval and Saguenay Railway Company |
| RSA | Rail Sling Attachment |
| RSB | Railway Shop Battalion |
| RSB | Rochester Subway |
| RSC | Rail Simulator Content |