| Abbreviation | Definition |
|---|---|
| STOP | Spin Tires On Pavement |
| STOVL | Short Take-Off and Vertical Landing |
| STP | Sailing To Philadelphia |
| STP | Seattle To Portland |
| STP | Surface Transportation Program |
| STP | Sustainable Transportation Professional |
| STPI | Statewide Transportation Projects Inventory |
| STPP | Service Transportation Policy Project |
| STPP | Surface Transportation Policy Partnership |
| STPP | Surface Transportation Policy Project |
| STRA | Specialty Transportation Rental Association |
| STRACNET | Strategic Rail Corridor Network |
| STRAIN | Structure Replacement and Improvement Needs (report) |
| STREET | Simulating Transportation for Realistic Engineering Education and Training |
| STRIP | Spare Tire Removal In Progress |
| STRS | Strategic Transportation Research Study |
| STRV | Space Technology Research Vehicle |
| STS | Schuylkill Transportation System |
| STS | Seville Touring Sedan |
| STS | Sexy Touring Sedan |