| Abbreviation | Definition |
|---|---|
| RNRX | Road & Rail Services |
| ROBZ | Robco Transportation |
| ROBZ | Robco Transportation Incorporated |
| ROCK | Chicago, Rock Island and Pacific Railroad |
| ROCX | Rock Island Improvement (Rocky Mountain Transportation Services) |
| ROCX | Rocky Mountain Transportation Services |
| ROEZ | Roehl Transport |
| ROEZ | Roehl Transport Incorporated |
| ROIX | Shintech |
| ROIX | Shintech Incorporated |
| ROLU | Ro-Lo Pacific Line |
| RONY | Railroads of New York |
| ROPX | Rail Operators |
| ROPX | Rail Operators Incorporated |
| ROSB | Railroad Operations and Safety Branch |
| ROSB | Railroad Operations Safety Branch |
| ROYU | Royal Netherlands |
| ROYX | TCL |
| RPAX | Rhone- Poulenc Basic Chemicals Company |
| RPAX | Rhone-Poulenc Basic Chemicals Company |