| Compagnia ferroviaria |
Logo & collegamento |
Odokyu Electric Railway  |
 |
Oensingen-Balsthal-Bahn (OeBB)  |
 |
Office national des chemins de fer (ONCF)  |
 |
| Ohmi Railway |
 |
| Oigawa Railway |
 |
Ontario Northland  |
 |
Operail  |
 |
Öresundståg  |
 |
Organismós Sidirodrómon Elládos (OSE)  |
 |
Ostdeutsche Eisenbahn GmbH (ODEG)  |
 |
Österreichische Bundesbahnen (ÖBB)   |
 |
| ÖstgötaTrafiken |
 |
Ouigo  |
 |
O'zbekiston Temir Yo'llari (Uzbekistan Railways)  |
 |
