| Word | Description |
| Sealant | The material used in a saw slot of loop detector to seal the looped and twisted wires in the slot. |
| Semi-Traffic-Actuated Controller Assembly | A type of traffic actuated controller assembly in which means are provided for traffic actuation on one or more but not all approaches to the intersection (NEMA). See Also: Traffic-Actuated Controller Assembly, Full-Traffic-Actuated Controller, and/or Pedestrian-Actuated Controller Assembly |
| Serial Cable | UPP Serial Cable Unil Serial Cable |
| SHRP | Strategic Highway Research Program |
| Spike | Spike |