| Rank | Country | dual gauge | Railways |
| Georgia | | total: 1,612 km broad gauge: 1,575 km 1.520-m gauge (1,575 electrified) narrow gauge: 37 km 0.912-m gauge (37 electrified) (2006) |
| Germany | | total: 48,215 km standard gauge: 47,962 km 1.435-m gauge (20,278 km electrified) narrow gauge: 229 km 1.000-m gauge (16 km electrified); 24 km 0.750-m gauge (2006) |
| Ghana | | total: 953 km narrow gauge: 953 km 1.067-m gauge (2006) |
| Gibraltar | | void |
| Greenland | | void |
| Grenada | | void |
| Guam | | void |
| Guatemala | | total: 886 km narrow gauge: 886 km 0.914-m gauge (2006) |
| Guernsey | | void |
| Guinea | | total: 837 km standard gauge: 175 km 1.435-m gauge narrow gauge: 662 km 1.000-m gauge (2006) |
| Guinea-Bissau | | void |
| Guyana | | void |
| Haiti | | void |
| Heard Island and McDonald Islands | | void |
| Holy See (Vatican City) | | void |
| Honduras | | total: 699 km narrow gauge: 279 km 1.067-m gauge; 420 km 0.914-m gauge (2006) |
| Hong Kong | | void |
| Hungary | | total: 8,057 km broad gauge: 36 km 1.524-m gauge standard gauge: 7,802 km 1.435-m gauge (2,628 km electrified) narrow gauge: 219 km 0.760-m gauge (2006) |
| Iceland | | void |
| India | | total: 63,221 km broad gauge: 46,807 km 1.676-m gauge (17,343 km electrified) narrow gauge: 13,290 km 1.000-m gauge (165 km electrified); 3,124 km 0.762-m gauge and 0.610-m gauge (2006) |
| Indian Ocean | | void |
| Indonesia | | total: 6,458 km narrow gauge: 5,961 km 1.067-m gauge (125 km electrified); 497 km 0.750-m gauge (2006) |
| Iran | | total: 8,367 km broad gauge: 94 km 1.676-m gauge standard gauge: 8,273 km 1.435-m gauge (146 km electrified) (2006) |
| Iraq | | total: 2,272 km standard gauge: 2,272 km 1.435-m gauge (2006) |