Rail Types
1. What is a Rail?
A rail is a high-carbon rolled steel section which, together with another parallel rail and the intervening sleepers & fastenings, forms the track on which railway vehicles run. It is the most critical load-carrying element—wheels transmit vertical, lateral and longitudinal forces to it; hence its metallurgy, geometry and weight decide safety, speed and maintenance effort.
2. Technical Specifications & Nomenclature
| Parameter | Value / Formula | Remarks |
|---|---|---|
| Standard length (L) | 13 m (42.65 ft) for 60 kg, 52 kg & 90 R; 26 m welded panels in LWR | Earlier 11.8 m & 12.8 m existed |
| Nominal weight (W) | Expressed in kg/m or lbs/yd | 60 kg ≈ 60 kg/m ≈ 121 lb/yd |
| Section modulus (Z) | I/y_max | Bending strength ∝ Z |
| Wear allowance | 2–3 mm on head top & 1 mm on gauge face | Re-profiling limit 8 mm vertical wear |
| Chemical composition (60 kg – IRS T-12) | C 0.60–0.80 %, Mn 0.80–1.30 %, Si 0.15–0.55 %, S & P ≤ 0.04 % | Micro-alloyed (Cr, V) for 1080 grade |
| Hardness (BH) | 280–350 for plain carbon; ≥ 380 for head-hardened (HH) | HH rails used in curves ≤ 1000 m radius |
| Contact stress limit | 2100 MPa (von-Mises) | Influences rail head radius design |
3. Indian Rail Sections – Evolution & Comparison
| Rail | Introduced | Weight (kg/m) | Height (mm) | Head (mm) | Web (mm) | Foot (mm) | Status (2024) |
|---|---|---|---|---|---|---|---|
| 90 R | 1920 | 44.65 | 142.9 | 66.7 | 13.5 | 127 | Phased out (≤ 5 % network) |
| 52 kg | 1950 | 51.92 | 156 | 67 | 16 | 140 | 35 % route-km |
| 60 kg (UIC-60 profile) | 1985 | 60.34 | 172 | 74.3 | 16.5 | 150 | 60 % network; mandatory for ≥ 160 km/h |
| 60 kg HH | 1997 | 60.34 | 172 | 74.3 | 16.5 | 150 | 12 % of 60 kg; target 25 % by 2030 |
| 75 kg (experimental) | 2022 (RDSO trial) | 74.4 | 185 | 80 | 20 | 160 | Trial on DFC (Rewari–Mewat) |
4. Rail Classifications in Use
A. By Weight (Indian Railways categorisation)
- Heavy: ≥ 52 kg/m (52 kg, 60 kg, 75 kg)
- Medium: 40–52 kg/m (90 R, 75 R rarely found)
- Light: < 40 kg/m (35 R, 25 R on NG/Metro depots)
B. By Metallurgy & Heat-treatment
- Plain-Carbon (IRS T-12)
- Micro-Alloyed (MA) – 1080 grade
- Head-Hardened (HH) – Bainitic/martensitic layer 25 mm deep
- Hypereutectoid (HE) – 0.9 % C, lab trial for 200 km/h
C. By Service Application
- Straight Track (ST) rails
- Curve rails (high wear)
- Turnout rails (wing, check, crossing rails)
- Welded-rail (LWR) panels
- Conductor rail (3rd rail 750 V DC metros)
5. Manufacturing & Quality Control
- Steel route: Blast furnace → Basic Oxygen Furnace → Continuous casting blooms (320 mm × 320 mm) → Universal mill rolling → Online water quenching (for HH) → Straightening → Ultrasonic testing (UST) → Brand marking.
- New Mills: SAIL, Bhilai (exp. to 2.0 MT), JSPL Raigarh, RINPL Vizag.
- Quality norms: IRS T-12:2019 (replaced 1996), EN 13674-1:2017, BS 11-1985.
- Brand mark example:
60 Ⅱ 13 05 23 SAIL T-12 1080 HH ← △
(kg/m, II quality, 13 m, May-2023, mill, grade, heat-treated, directional arrow)
6. Historical Milestones
| Year | Event |
|---|---|
| 1853 | First rail (50 lb/yd ≈ 25 kg/m) on BB&CI |
| 1920 | 90 R becomes “standard” on MG & FG |
| 1950 | 52 kg adopted for high-speed routes (120 km/h) |
| 1985 | Decision to switch to 60 kg UIC profile (speed-cum-freight) |
| 1992 | First HH rail (imported) laid on Agra-Gwalior curve |
| 1997 | Indigenous HH rail production started at Bhilai |
| 2005 | IRS T-12:2005 specifies 1080 grade MA rails |
| 2016 | 260 m long rail panels (Bhilai) – longest in Asia |
| 2023 | 100 % UST mandatory; QR-coded stamping launched |
7. Current Status & Recent Updates (2024)
- Indian Railways consumes ≈ 7.5 lakh tonnes rail/yr (60 % HH).
- Policy: All new lines & renewals ≥ 160 km/h to use 60 kg HH; ≤ 100 km/h may continue 52 kg.
- Long-welded rail (LWR) now 260 m factory panels, field flash-butt welded to 1 km+ strings.
- DFC (E & W) completely 60 kg HH on concrete sleepers with elastic fastenings.
- Green initiative: Waste rail recycled into “R-Girders” for ROBs (Rail Over Bridges).
- RDSO developing 75 kg rail for 25-tonne axle-load dedicated freight corridors & heavy-haul (30 t) trials.
- Import substitution: Import of rails almost nil since FY 2021-22.
8. Weight vs Speed-Axle Load Matrix (IR Guideline)
| Speed (km/h) | Axle Load (t) | Recommended Rail |
|---|---|---|
| ≤ 100 | ≤ 20 | 52 kg |
| ≤ 130 | ≤ 22.5 | 60 kg |
| ≤ 160 | ≤ 22.5 | 60 kg HH |
| ≤ 200 | ≤ 22.5 | 60 kg HH + MA |
| ≥ 200 (future) | ≤ 25 | 75 kg HH (trial) |
9. Quick-Fire Data Points for MCQ
- Minimum vertical wear permitted before rail closure: 8 mm (IRPWM).
- Length tolerance for 13 m rail: ±10 mm.
- Straightness limit (edge camber): ≤ 0.5 mm in 1 m.
- Head width of 60 kg rail: 74.3 mm.
- Foot width of 90 R rail: 127 mm.
- Thermal stress in LWR at 40 °C ≈ 1.15 t/mm² → 115 t for 60 kg.
- Head-hardened depth: 25 mm minimum.
- HH rail life extension on 600 m radius curve: ≈ 2.5 × plain carbon.
- Mill trial of hypereutectoid rail: RDSO & SAIL, 2021.
10. Practice MCQs
Q1. Which rail section is heaviest among the following currently used on Indian Railways main line?
- (a) 90 R
- (b) 52 kg
- (c) 60 kg
- (d) 75 kg (trial)
Ans
c (60 kg is standard; 75 kg is still under trial)Q2. The standard length of a 60 kg rail panel supplied by SAIL for LWR track is
- (a) 11.8 m
- (b) 13 m
- (c) 26 m
- (d) 260 m
Ans
b (13 m individual; 260 m welded panel)Q3. Head-hardened rails are primarily recommended for
- (a) Stations yards
- (b) Sharp curves
- (c) Level crossings
- (d) Bridge approaches
Ans
bQ4. Chemical composition of IRS T-12 1080 grade rail contains carbon in the range of
- (a) 0.45 – 0.60 %
- (b) 0.60 – 0.80 %
- (c) 0.82 – 0.90 %
- (d) 0.90 – 1.20 %
Ans
bQ5. The height of 52 kg rail section is approximately
- (a) 142 mm
- (b) 156 mm
- (c) 172 mm
- (d) 185 mm
Ans
bQ6. Which of the following is NOT a classification of rail by Indian Railways?
- (a) Heavy
- (b) Medium
- (c) Super-heavy
- (d) Light
Ans
cQ7. The first heat-treated (head-hardened) rail in India was laid in the year
- (a) 1985
- (b) 1992
- (c) 1997
- (d) 2005
Ans
b (imported); indigenous in 1997Q8. The rail brand mark “60 II 13 08 22 SAIL T-12” indicates
- (a) 60 lb/yd rail
- (b) 60 kg/m rail of second quality
- (c) 60 m length
- (d) 60 tonnes tensile strength
Ans
bQ9. As per latest policy, all new lines with speed ≥ 160 km/h must use
- (a) 90 R
- (b) 52 kg
- (c) 60 kg plain carbon
- (d) 60 kg head-hardened
Ans
dQ10. The minimum depth of head hardening specified for HH rail is
- (a) 10 mm
- (b) 15 mm
- (c) 25 mm
- (d) 35 mm
Ans
cQ11. Which mill rolled the first 260 m long rail panel in India?
- (a) JSPL
- (b) RINPL
- (c) SAIL-Bhilai
- (d) Tata Steel
Ans
cQ12. The foot width of 60 kg UIC rail is
- (a) 127 mm
- (b) 140 mm
- (c) 150 mm
- (d) 160 mm
Ans
cQ13. Vertical wear limit beyond which a rail must be replaced in Indian Railways is
- (a) 5 mm
- (b) 6 mm
- (c) 8 mm
- (d) 10 mm
Ans
cQ14. The rail section 90 R weighs approximately
- (a) 40 kg/m
- (b) 44.65 kg/m
- (c) 52 kg/m
- (d) 60 kg/m
Ans
bQ15. Micro-alloyed 1080 grade rails achieve their strength mainly due to
- (a) Increased manganese and vanadium
- (b) Increased sulphur
- (c) Decreased carbon
- (d) Heavy phosphorus
Ans
aQ16. The trial of 75 kg rail is being done primarily for
- (a) Metro tracks
- (b) Heritage hill railways
- (c) Dedicated freight corridors with 25 t axle load
- (d) 3rd rail electrification
Ans
cRemember: 60 kg HH rails → 160 km/h; 75 kg rails → Future heavy-haul; 90 R → Only on remaining MG/NG heritage sections.
BETA
