Sleeper Types
Sleeper Types – Railway General Knowledge Capsule
1. Definition & Purpose
- Sleeper (US: Tie) is a transverse member laid below rails to:
- Transfer wheel loads to ballast & formation
- Maintain correct gauge & alignment
- Provide elastic medium between rail & ballast
- Facilitate track circuiting & return current path (in electrified sections)
2. Classification of Sleepers on Indian Railways
| Broad Group | Sub-type | Material | Key Standard | Typical Life | Use on IR |
|---|---|---|---|---|---|
| Wooden | Hardwood & Softwood (Sal, Teak, Deodar, Casuarina) | Timber | RDSO T-12-2001 | 12–15 yrs | ≤ 10 % of total; mainly in approach of bridges, points & crossings |
| Steel | CST-9, Steel trough, 2-piece plate, Yoke plate | Mild steel | IRS-T-32-2008 | 35–40 yrs | < 1 %; limited to bridges & special locations |
| Cast Iron | CST-9, CST-12, Two-block, Plate sleeper | Cast iron | IRS-T-24-2008 | 35–40 yrs | < 1 %; obsolete except on girder bridges |
| Concrete | Mono-block (M-44, M-46), Two-block, T-5 post-tensioned, Pre-stressed (PRC) | RCC, Pre-stressed concrete | IRS-T-39-2022 (latest 5th rev.) | 50–60 yrs | ~98 % of all new track since 1990 |
| Composite/Plastic | Recycled HDPE + rubber filler | Waste plastic | RDSO S/N-183-2019 Pilot | 40 yrs (lab) | Trial on 3 km section (WR) as on 2023 |
3. Technical Specifications (Latest IRS)
A. Pre-stressed Mono-block Concrete Sleeper (M-46 profile)
- Density 2,560 kg/m³
- Weight 280 kg (±5 kg)
- Length 2,750 mm (BG)
- Width at rail seat 280 mm
- Depth at centre 205 mm
- 28-day characteristic strength 60 MPa (M-60 grade)
- Tensioning wires 7 mm φ high-tensile (1,570 MPa)
- Initial pre-stress 1,000 MPa (single stage tensioning)
- Elastic modulus 38 kN/mm²
- Track modulus offered 90–110 N/mm³ (higher than wooden)
- Lateral resistance 1.7 × wooden sleeper
- Design wheel load 32.5 t (32.5 tonne axle) @ 160 kmph
- Spacing (normal BG) 600 mm c/c (1,660 sleepers/km)
- Sleeper density 1,540–1,660 nos./km (LWR track 60 kg 92 UTS rail)
B. Wooden Sleeper
- Standard sizes BG: 2,750 × 250 × 130 mm
- Adzing: 125 mm wide × 13 mm deep; 1 in 20 inward cant
- 8 anti-creep / gauge holding fittings (dog spikes, fang bolts)
- Treatment: Copper-Chrome-Arsenic (CCA) 8–12 kg/m³ retention
C. Steel Trough Sleeper
- Rolled from 22 mm thick MS plate
- Weight: 85 kg; Length: 2,750 mm
- Gauge holding: By projecting lugs & key holes for loose jaws
4. Historical Milestones
| Year | Event |
|---|---|
| 1853 | First IR track (Bombay–Thane) – Imported wooden (Jarrah) sleepers |
| 1925 | Steel trough sleepers adopted on girders of GIPR |
| 1930 | CST-9 cast iron sleeper designed by “Concrete Steel & Timber Co.” |
| 1956 | Indian Standard sleeper sizes codified (IS: 1138) |
| 1966 | First experimental PRC sleeper plant set up at Allahabad (MFP) |
| 1974 | Mono-block PRC sleeper regularised on 25 kV AC electrified track |
| 1983 | Pandrol clip introduced with PRC sleeper (RDSO T-39) |
| 1987 | Indigenous production of 60 kg rails & matching M-46 sleepers |
| 1995 | Decision: All new BG track to be with PRC sleepers only (except bridges) |
| 2016 | 1st trial of composite recycled plastic sleeper (WR) |
| 2022 | 5th revision of IRS-T-39 (permitting 60 kg & 52 kg rail on same sleeper) |
5. Current Status (2023-24)
- Total route km on Indian Railways: 68,043 km
- Total sleepers: ≈ 115 crore (1.15 billion)
- Share of concrete sleepers: 96.8 %
- Sleeper plants: 22 (16 MOF – Ministry-owned, 6 private)
- Annual capacity: 2.8 crore PRC sleepers
- Green initiative: 1.2 crore wooden sleepers saved per year by PRC switch-over
- Plastic sleeper pilot: 3 km (Virar–Dahanu) under monitoring; RDSO report due 2024
- Next-gen: 250 kmph capable “H-sleeper” (pre-stressed) under development by RDSO
6. Comparative Advantages
| Parameter | Wooden | Steel | Cast Iron | Concrete | Composite |
|---|---|---|---|---|---|
| Initial cost | Medium | High | Medium | Low | High |
| Track modulus | Low | High | Medium | Very high | Medium |
| Maintenance | High | Medium | Medium | Very low | Very low |
| Scrap value | Nil | High | High | Nil | Medium |
| Fire resistance | Poor | Good | Good | Excellent | Good |
| Corrosion | Bio-decay | Rust | Rust | Alkali-silica | UV-degradation |
| Handling | Easy | Heavy | Brittle | Heavy (280 kg) | Light (165 kg) |
7. Quick Facts to Memorise
- “Sleeper density” is expressed as number of sleepers per km (NOT per mile).
- Heaviest sleeper on IR: Pre-stressed concrete M-46 (280 kg).
- Longest lasting: PRC (50-60 yrs) → almost 2× CI/Steel.
- Eco-friendly: Every PRC sleeper saves ~0.07 m³ of forest wood.
- Standard packing: 50 sleepers per rake (stack height 1.8 m).
- White patch on PRC sleeper → indicates pre-stressing zone (tensioned).
- Blue stripe on side → 60 kg rail seat; Red stripe → 52 kg rail seat (new coding).
8. 15+ MCQs (Railway Exam Pattern)
1. Which sleeper type offers the highest track modulus?
Ans: Pre-stressed concrete sleeper
2. The weight of a standard BG pre-stressed concrete sleeper (M-46) is approximately?
Ans: 280 kg
3. Indian Railways decided in 1995 that all new BG tracks would be laid only with which sleeper?
Ans: Pre-stressed concrete sleeper
4. Which chemical treatment is specified for wooden sleepers on IR?
Ans: Copper-Chrome-Arsenic (CCA)
5. The first experimental PRC sleeper plant of IR was set up at?
Ans: Allahabad (MFP)
6. What is the spacing of sleepers for BG LWR track with 60 kg rail?
Ans: 600 mm centre-to-centre
7. Which sleeper is also known as the “CST-9” sleeper?
Ans: Cast iron pot sleeper
8. The white paint patch on the side of a PRC sleeper indicates?
Ans: Zone of pre-stressing (tensioned wires)
9. As per latest IRS-T-39 revision, the minimum 28-day compressive strength of concrete for PRC sleeper is?
Ans: 60 MPa (M-60 grade)
10. Which of the following sleeper types is the heaviest?
Ans: Pre-stressed concrete sleeper
11. The trial stretch of recycled plastic composite sleeper on Western Railway is located between?
Ans: Virar – Dahanu (3 km)
12. Which sleeper requires “adzing” of the rail seat?
Ans: Wooden sleeper
13. The lateral resistance of PRC sleeper is about how many times that of a wooden sleeper?
Ans: 1.7 times
14. Which sleeper type is prohibited in new track on Indian Railways except in bridges & special locations?
Ans: Steel sleeper
15. The standard length of a BG wooden sleeper is?
Ans: 2750 mm
16. “Sleeper density” 1540 M means?
Ans: 1540 sleepers per km
17. Which colour stripe on new PRC sleeper indicates suitability for 60 kg rail?
Ans: Blue
18. The approximate life of a steel trough sleeper on Indian Railways is?
Ans: 35-40 years
BETA
