| Abbreviation | Definition |
|---|---|
| SRSU | Sea- Road Shipping, S. A., Miami, Florida |
| SRSU | Sea-Road Shipping SA Miami FL |
| SRSX | Sperry Rail Service |
| SRTF | Southport Rail Transport Forum |
| SRTO | Single Rail Transfer Operator |
| SRTX | Southwind Rail Travel Limited |
| SRY | Southern Railway of British Columbia |
| SRY | Southern Railway of British Columbia Limited |
| SRYC | Sierra Railway Company of California |
| SRYC | Sierra Railway of California |
| SRY-VI | Southern RailwaY of British Columbia on Vancouver Island |
| SS | Sand Springs Railway |
| SS | Sand Springs Railway Company |
| SS | Switch Stand |
| SSA | Secondary Switching Area |
| SSAM | Sault Ste. Marie Bridge (Wisconsin Central) |
| SSAM | Sault Ste. Marie Bridge Company |
| SSC | Southern Switching |
| SSC | Southern Switching Company |
| SSCU | States Steamship |