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.
Practice MCQs
Question:01 What is the exact width of Indian Broad Gauge?
A) 1 600 mm
B) 1 676 mm
C) 1 435 mm
D) 1 524 mm
Show Answer
Correct Answer: B
Explanation: Indian Broad Gauge is precisely 1 676 mm (5 ft 6 in) between the inner faces of the rails, the widest standard track gauge in regular use worldwide.
Question:02 The Unigauge policy of Indian Railways was announced in which Railway Budget?
A) 1990-91
B) 1991-92
C) 1992-93
D) 1993-94
Show Answer
Correct Answer: C
Explanation: The Unigauge policy, aimed at converting all metre-gauge and narrow-gauge lines to broad gauge for seamless freight and passenger movement, was formally announced in the 1992-93 Railway Budget.
Question:03 Metre Gauge (MG) measures
A) 762 mm
B) 1 000 mm
C) 1 435 mm
D) 1 676 mm
Show Answer
Correct Answer: B
Explanation: Metre Gauge is defined as 1 000 mm (1 metre) between the rails.
Question:04 Which of the following sections still runs on 610 mm gauge?
A) Darjeeling Himalayan Railway
B) Nilgiri Mountain Railway
C) Matheran Hill Railway
D) Kalka–Shimla Railway
Show Answer
Correct Answer: C
Explanation: The Matheran Hill Railway in Maharashtra continues to operate on the 610 mm (2-ft) narrow gauge, making it the only section among the choices that still uses this gauge.
Question:05 As on 31 March 2024, approximately what percentage of Indian Railways route-km is on Broad Gauge?
A) 88 %
B) 92 %
C) 96 %
D) 99 %
Show Answer
Correct Answer: C
Explanation: As per Indian Railways’ official data, about 96 % of the total route-kilometres had been converted to Broad Gauge by 31 March 2024.
Question:06 The fastest train in India (Gatimaan Express) operates on which gauge?
A) Meter Gauge
B) Broad Gauge
C) Narrow Gauge
D) Standard Gauge
Show Answer
Correct Answer: B
Explanation: Gatimaan Express runs on Broad Gauge (1,676 mm) track, the predominant gauge across Indian Railways.
Question:07 762 mm is categorised as
A) Broad Gauge
B) Metre Gauge
C) Narrow Gauge
D) Standard Gauge
Show Answer
Correct Answer: C
Explanation: In Indian Railways, any track gauge less than 1,435 mm (Standard Gauge) and equal to or less than 1,000 mm is classified as Narrow Gauge; 762 mm is a common Narrow Gauge dimension.
Question:08 Which gauge permits the heaviest axle-load in Indian Railways?
A) Narrow Gauge
B) Meter Gauge
C) Broad Gauge
D) Standard Gauge
Show Answer
Correct Answer: C
Explanation: Broad Gauge (1676 mm) has the widest track and strongest track structure, allowing Indian Railways to carry the heaviest axle loads—up to about 22.9 t for freight wagons—compared with Meter Gauge (~18 t) and Narrow Gauge (~10 t).
Question:09 Delhi–Mumbai trunk route was fully converted from MG to BG during
A) 1988-89
B) 1990-91
C) 1992-93
D) 1994-95
Show Answer
Correct Answer: C
Explanation: The entire Delhi–Mumbai trunk route was progressively gauge-converted from Metre Gauge to Broad Gauge and the last section was completed in the financial year 1992-93.
Question:10 The structure gauge of a 1 676 mm track is officially known as
A) Indian Metre Gauge loading gauge
B) Indian Broad Gauge loading gauge
C) Indian Narrow Gauge loading gauge
D) Indian Standard Gauge loading gauge
Show Answer
Correct Answer: B
Explanation: The 1 676 mm (5 ft 6 in) track is classified as Indian Broad Gauge, and its corresponding structure gauge is therefore termed the Indian Broad Gauge loading gauge.
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