Types of Rail Sleeper

Types of Rail Sleeper

1. Wooden sleepers

2. Concrete sleepers

3. Steel sleepers

4. Cast iron sleepers

5. Composite sleepers

Wooden Sleepers

These are sleepers made of wood. Wooden sleepers are used since olden days. These are still widely using in some western countries. Either hardwood or softwood can be used to make wooden sleepers. However, hardwood sleepers made of oak, jarrah, teak wood are more famous.

Advantages

1. They are cheap and easy to manufacture

2. They are easy to handle without damage

3. They are more suitable for all types of ballast

4. They absorb shocks and vibrations better than other types of sleepers.

5. Ideal for track circuited sections

6. Fittings are few and simple in design

7. Good resilience

8. Ease of handling

9. Adaptability to non standard situation

10. Electrical insulation

Disadvantages

1. They are easily liable to attack by vermin and weather

2. They are susceptible to fire

3. It is difficult to maintain gauge in case of wooden sleepers

4. Scrap value is negligible

5. Their useful life is short about 12 to 15 years.

Concrete Sleepers

Concrete sleepers are manufactured by concrete with internal reinforcement. Concrete sleepers used in many countries due to its high stability and small maintenance. These are more suitable for high speed rails.

Most of the concrete sleepers are made from pre-stressed concrete in which internal tension is induced into the sleeper before casting. Hence, the sleeper withstand well against high external pressure.

Advantages

1. It is more durable having greater life (up to 50years)

2. It is economical as compare to wood and steel.

3. Easy to manufacture.

4. It is not susceptible to vermin attack

5. It is not susceptible to fire

6. Good for track circuited areas

Disadvantages

1. It is brittle and cracks without warning.

2. It cannot be repaired, and required replacement.

3. Fittings required are greater in number.

4. No scrap value

Steel Sleepers

Steel sleepers are more often used because of stronger than wood and economical than concrete. They also have good life span. They are molded in trough shape and placed on ballast in inversed trough shape.

• Steel ties are used where wood or concrete is not favorable, for example in tunnels with limited headway clearance

• They are also used in heavy curvature prone to gage widening.

• This type of steel ties can cause problem to signals control system

• Some problems of fatigue cracking have also experienced.

• Due to the increasing shortage of timber in the country and other economic factors have led to the use of steel and concrete sleepers on railways.

In the design of Steel sleeper, the following are considered:

• It should maintain perfect gauge

• Can fix the rail and there should be no movement longitudinally

• Should have sufficient effective area to transfer load from rail to ballast.

• The metal of sleepers should be strong enough to resist bending

• The design life should be 35 years

Advantages of Steel Sleepers

1. It is more durable. Its life is about 35 years

2. Lesser damage during handling and transport

3. It is not susceptible to vermin attack

4. It is not susceptible to fire

5. Its scrap value is very good

Disadvantages of Steel Sleepers

1. It is liable to corrosion.

2. Not suitable for track circuiting

3. It can be used only for rails for which it is manufactured

4. Cracks at rail seats develop during the service.

5. Fittings required are greater in number

Cast Iron Sleepers

Cast iron sleepers are widely used in the world especially in Indian railways. They are available in 2 types, pot type sleepers and plate type sleepers. Pot type sleepers are not suitable for curves sharper than 4 degrees. CST 9 type sleepers more famous in Indian railways.

They are further divided into two categories:

1. Cast iron pot type sleepers

2. Cast iron plate type sleepers

Advantages of Cast Iron Sleepers

1. Service life is very long

2. Less liable to corrosion

3. Form good track for light traffic up to 110 kmph as they form rigid track subjected to vibrations under moving loads without any damping

4. Scrap value is high

Disadvantages of Cast Iron Sleepers

1. Gauge maintenance is difficult as tie bars get bent up

2. Not suitable for circuited track

3. Need large number of fittings

4. Suitable only for stone ballast

5. Heavy traffic and high speeds (>110kmph) will cause loosening of keys and development of high creep

Composite Sleepers

Composite sleepers are modern type sleepers which are made from waste plastic and rubber. Hence, it is also called as plastic sleepers. They have many combined properties of all other types.

Advantages

• Composite sleepers are serviceable for longer spans about 50 years.

• Composite sleepers are eco-friendly sleepers.

• They are light in weight but possess great strength.

• Their scrap value is good because of recyclable property of composite sleepers.

• They can be resized easily like wooden sleepers. So, they can be used for any type of rail section.

• Vibrations received from rails are reduced well by these composite sleepers.

Disadvantages

• Composite sleepers are not that much good against fire.

• The cost of sleepers may increase for large scale production.