Correct Answer - Option 2 : 1 and 3 only
Explanation:
Concrete Sleeper:
(i) Concrete sleeper is a kind of railway sleeper made of steel-reinforced concrete. With the characteristic of water-resistant, sun-resistant, and corrosion-resistant.
(ii) Concrete sleeper has been widely used all over the world since 1950.
Advantages of Concrete Sleepers:
- It is more durable having greater life (up to 50 years)
- It is economical as compared to wood and steel.
- Concrete sleepers can generally be mass-produced using local resources.
- Easy to manufacture.
- It is not susceptible to vermin attack
- It is not susceptible to fire
- Good for track circuited areas
Disadvantages of Concrete Sleepers
- It is brittle and cracks without warning.
- It cannot be repaired and required replacement.
- Fittings required are greater in number.
- No scrap value
Advantages of Wooden Sleepers:
- They are cheap and easy to manufacture
- They are easy to handle without damage
- They are more suitable for all types of ballast
- They absorb shocks and vibrations better than other types of sleepers.
- Ideal for track circuited sections
- Fittings are few and simple in design
- Good resilience
- Ease of handling
- Adaptability to non-standard situation
- Electrical insulation
Disadvantages of Wooden Sleepers:
- They are easily liable to attack by vermin and weather
- They are susceptible to fire
- It is difficult to maintain gauge in the case of wooden sleepers
- The scrap value is negligible
- Their useful life is short about 12 to 15 years.
Advantages of Steel Sleepers:
- It is more durable. Its life is about 35 years
- Lesser damage during handling and transport
- It is not susceptible to vermin attack
- It is not susceptible to fire
- Its scrap value is very good
Disadvantages of Steel Sleepers:
- It is liable to corrosion.
- Not suitable for track circuiting
- It can be used only for rails for which it is manufactured
- Cracks at rail seats develop during the service.
- Fittings required are greater in number
Advantages of Cast Iron Sleepers:
- Service life is very long
- Less liable to corrosion
- Form good track for light traffic up to 110 kmph as they form rigid track subjected to vibrations under moving loads without any damping
- Scrap value is high
Disadvantages of Cast Iron Sleepers:
- Gauge maintenance is difficult as tie bars get bent up
- Not suitable for circuited track
- Need a large number of fittings
- Suitable only for stone ballast
- Heavy traffic and high speeds (>110kmph) will cause loosening of keys and development of high creep
