Railway Track Gauges
Railway Track Gauges
Overview
Track gauge is the minimum distance between the running faces of two rails. Indian Railways (IR) classifies its routes on the basis of gauge width and has progressively converted almost the entire network to the 1 676 mm “Broad Gauge (BG)” since the Unigauge policy of 1992.
Key Facts & Figures
| Fact | Detail |
|---|---|
| 1. Broad Gauge (BG) width | 1 676 mm (5 ft 6 in) |
| 2. Metre Gauge (MG) width | 1 000 mm |
| 3. Narrow Gauge (NG) – regular | 762 mm (2 ft 6 in) |
| 4. Narrow Gauge – toy/special | 610 mm (2 ft) |
| 5. % of IR route-km on BG (Mar-2024) | ≈ 96 % |
| 6. Unigauge year of announcement | 1991-92 (Railway Budget 1992-93) |
| 7. First BG train in India | Red Hill Railway, 1837 (near Chennai) |
| 8. First MG track in India | Delhi–Rewari–Ahmedabad, 1873 |
| 9. Fastest section on BG | Gatimaan Express – 160 km/h (Delhi–Agra) |
| 10. Highest BG section (RL) | Ghum (2 258 m) on Darjeeling Himalayan NG |
| 11. Longest BG electrified section | Dibrugarh–Kanyakumari (4 200 km+) |
| 12. Universal BG sleeper type | 52-kg/90-UG pre-stressed concrete |
| 13. MG sleeper type (old) | Steel trough / wooden |
| 14. BG loading gauge (max width) | 3 660 mm (CBC wagons) |
| 15. NG loading gauge (762 mm) | 2 590 mm |
| 16. Minimum curve radius – BG (plain) | 175 m |
| 17. Minimum curve radius – MG (plain) | 120 m |
| 18. Transition from MG to BG on Delhi–Mumbai | Completed 1992-93 |
| 19. Last MG section closed (2022) | Mavli–Marwar (Rajasthan) |
| 20. UNESCO NG heritage lines | Darjeeling, Nilgiri, Kalka-Shimla, Matheran |
Important Points
- BG is the “standard” gauge of Indian Railways; all new lines sanctioned since 1992 are BG.
- MG survives mainly on heritage/heritage-inclined routes (e.g., Patalpani–Kalakund).
- 762 mm NG is also called “2 ft 6 in NG”; 610 mm is the “toy-train” gauge.
- Gauge conversion projects are financed under “Unigauge” – a part of the Rashtriya Rail Vikas Yojana.
- Electrification is always done after gauge conversion to BG.
- BG allows 22.9 t axle-load (BCNHL wagons) vs 13.0 t on MG.
- Track modulus (stiffness) is highest on BG → higher speeds & heavier freight.
- Indian BG is 1 676 mm; world standard gauge (SG) is 1 435 mm – do NOT confuse.
- Loading gauge = structure gauge; it is independent of track gauge.
- Curve radius is sharper on MG/NG → ghats/hill sections prefer NG.
- Universal BG rail sections: 52 kg, 60 kg (UIC-60) & 68 kg (for heavy-haul).
- Sleepers density BG: 1 540/km (plain) → 1 660/km on curves ≤2°.
- Gauge tolerance (BG): +6 mm to –3 mm under 14 t vertical load.
- Maintenance blocks are longer on converted BG due to heavier traffic.
- Candidates often confuse “gauge” with “loading gauge” – remember gauge is rail-to-rail distance only.
Frequently Asked in Exams
- Width of Indian Broad Gauge in millimetres.
- Year of launching Unigauge policy.
- Which gauge is used by UNESCO World Heritage toy trains in India?
- Percentage of IR network already converted to BG (≈96 %).
- Minimum curve radius permitted on BG plain track.
BETA
