| Abbreviation | Definition |
|---|---|
| RR | Raised Rail |
| RR | Raritan River Railroad (Conrail) |
| RRAC | Royal Railway Agent Cambodia |
| RRB | Railroad Retirement Board's |
| RRBX | Rampart Range Corporation |
| RRC | RailRoad Commission of Texas |
| RRC | Respondek Railroad Corporation |
| RRCB | Railway Recruitment Control Board |
| RRCI | Redmont Railway |
| RRCI | Redmont Railway Company Incorporated |
| RRCO | Rochelle Railroad |
| RRCO | Rochelle Railroad Company |
| RRCX | Radar Railcar |
| RRCX | Radar Railcar Incorporated |
| RREX | General Electric Railcar Services Corporation |
| RREX | Rex Railway |
| RRF | Rotterdam Rail Feeding |
| RRG | RailRoad Generator Set |
| RRIU | Triton Containers |
| RRIX | Rader Railcar |