| Rank | Country | Railways |
| Iceland | void |
4 | 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 |
28 | Indonesia | total: 6,458 km narrow gauge: 5,961 km 1.067-m gauge (125 km electrified); 497 km 0.750-m gauge (2006) |
24 | 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) |
69 | Iraq | total: 2,272 km standard gauge: 2,272 km 1.435-m gauge (2006) |
53 | Ireland | total: 3,237 km broad gauge: 1,872 km 1.600-m gauge (37 km electrified) narrow gauge: 1,365 km 0.914-m gauge (operated by the Irish Peat Board to transport peat to power stations and briquetting plants) (2006) |
130 | Isle of Man | total: 65 km standard gauge: 7 km 1.067-m gauge (7 km electrified) narrow gauge: 58 km 0.914-m gauge (29 km electrified) note: primarily summer tourist attractions (2006) |
95 | Israel | total: 853 km standard gauge: 853 km 1.435-m gauge (2006) |
15 | Italy | total: 19,460 km standard gauge: 18,038 km 1.435-m gauge (11,354 km electrified) narrow gauge: 123 km 1.000-m gauge (123 km electrified); 1,299 km 0.950-m gauge (161 km electrified) (2006) |
| Jamaica | void |
| Jan Mayen | void |