| Abbreviation | Definition |
|---|---|
| PTIZ | Parkway Transport Incorporated |
| PTLX | General Electric Railcar Services Corporation |
| PTLX | Pullman Transport Leasing (GE Rail Services) |
| PTM | Portland Terminal (Pan Am Railways) |
| PTM | State Rail System |
| PTMX | Pittsburgh Transportation Museum Society |
| PTOX | PTO Incorporated |
| PTOX | PTO Rail |
| PTR | Port Terminal Railroad of South Carolina |
| PTRA | Port Terminal Railroad Association |
| PTRC | Portland Terminal Railroad |
| PTRC | Portland Terminal Railroad Company (Oregon) |
| PTRR | Port Townsend Railroad |
| PTRR | Port Townsend Railroad Incorporated |
| PTRU | South American Petrolite De Venezuela |
| PTRX | Petrolite Corporation |
| PTSU | Pacer International |
| PTSX | Petrosol International |
| PTSX | Petrosol International Incorporated |
| PTTX | TTX Company |