| Abbreviation | Designation | |
|---|---|---|
| u | Wendezugwagen (German) | classification |
| SE-U | Västmanland, Västmanlands län (Swedish) | country code |
| U | Stadtbahn (German) Suburban railway | train category |
| U | Untergrundbahn (German) Underground (BE), Subway (AE/CE), Metro (AuE) | train category |
| U | Uppsala C (Swedish) | station code |
| U | RB Erfurt, Regionalbereich Erfurt (German) | railway administration |