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Railway sleepers are the components on which the rails are placed with appropriate gauges.
These sleepers usually rest on ballast and are also called ties in a few areas. The load from rails when the train passes, is taken by these sleepers and is allocated to the ballast.
1. Functions of Railway Sleepers
The essential functions of Railway sleepers are to:
a. It maintains the rails strongly and keeps uniform gauges.
b. Transfer the load from the rails to the ballast or ground.
c. Reduce the vibrations coming from rails.
d. Offer longitudinal and lateral stability.
2. Classification of Railway Sleepers
Depending on the materials employed, railway sleepers are categorized into the following types:
a. Wooden sleepers
b. Concrete sleepers
c. Steel sleepers
d. Cast iron sleepers
e. Composite sleepers
a. Wooden Sleepers
These are sleepers prepared of wood. Wooden sleepers are employed since the olden days.
These are still commonly employed in some Western countries. Either hardwood or softwood can be employed to prepare wooden sleepers.
However, hardwood sleepers prepared of oak, jarrah, and teakwood are more well-known.
Advantages of Wooden Sleepers
The advantages of wooden sleepers are as mentioned below:
a. Wood sleepers are more inexpensive.
b. They are lightweight.
c. Fasteners can be efficiently fixed on it.
d. They are suitable insulators so, the rails are well protected.
e. Any sort of gauge can be supported by wooden sleepers.
f. They are appropriate for all types of rail divisions.
g. They are well suited for paths in coastal areas.
h. It can be effortlessly transported and managed while installed.
i. Easy to manufacture.
Disadvantages of Wooden Sleepers
The disadvantages of wooden sleepers are as mentioned below:
a. The life span of wooden sleepers is very undersized compared to others.
b. Vulnerable against fire.
c. Efficiently influenced by humidity which will generate dry rot, wet rot, etc.
d. Vermin attack can be likely if it is not adequately treated.
e. Insufficient creep opposition.
f. Sufficient concentration is needed even after spreading.
b. Concrete Sleepers
Concrete sleepers are prepared of concrete having internal reinforcement. Concrete sleepers are employed in multiple countries because of their high stability and negligible maintenance. These are better appropriate for high-speed rails.
Most concrete sleepers are constructed from pre-stressed concrete in which internal tension is generated into the sleeper before casting. Hence, the sleeper resists well against very high external pressure.
Advantages of Concrete Sleeper
The advantages of concrete sleeper are mentioned below:
a. Concrete sleepers are weightier than all other types hence providing good stability to the rails.
b. They possess a long life span so, economically preferable.
c. They have good Fire resistance.
d. Corrosion has not occurred in concrete sleepers.
e. Vermin attacks, decay, etc. problems aren’t raised.
f. Hence, they are appropriate for all kinds of soil and moisture requirements.
g. Bucking strength is better.
h. Concrete is a good insulator so, this kind of sleeper is more appropriate for circuited tracks.
i. Concrete sleepers maintain the track extremely and hold the gauge.
Disadvantages of Concrete Sleepers
The disadvantages of concrete sleepers are as follows:
a. Heavyweight, handling is hard.
b. For tracks on bridges and at crossings, concrete sleepers are not the best.
c. Damage may arise while transporting the precast concrete.
c. Steel Sleepers
Steel sleepers are more frequently employed because of stronger than wood and cheaper than concrete. They also possess good durability. They are set in a trough shape and positioned on ballast in an inverted trough shape.
Advantages of Steel Slippers
The advantages of steel slippers are as follows:
a. They are lightweight.
b. They are recyclable and hence own scrap value.
c. Life span of steel sleepers is better and is about 30 years.
d. They are good at resisting fire.
e. They contain useful opposition against creep.
f. They can’t be damaged by vermin etc.
g. They are well suited for tracks of high speeds and larger loads.
h. They maintain the rail strongly and connecting the rail to the sleeper is also straightforward.
i. Easy to Transport
j. Easy to place and install.
Disadvantages of Steel Slippers
The disadvantages of steel slippers are as follows:
a. Steel can be influenced by chemicals easily.
b. Steel sleepers need high maintenance.
c. They are not suitable for all types of ballast which is delivered as a bed for sleepers.
d. If derailment has occurred, they are harmed very poorly and not appropriate for reuse.
e. These are not appropriate for all types of rail sections and gauges.
d. Cast Iron Sleepers
Cast iron sleepers are commonly employed in the world, mainly in Indian railways. They are obtainable in 2 types, pot-type sleepers, and plate-type sleepers.
Pot-type sleepers are not fit for curves sharper than 4 degrees. CST 9 type sleepers were more well-known in Indian railways.
Advantages of Cast Iron Sleepers
The advantages of cast iron sleepers are as follows:
a. It normally long last up to 60 years.
b. Their manufacturing is also effortless and it can be accomplished locally so, there is no requirement for more extended transportation.
c. No chance of vermin attack in the cast iron sleepers.
d. They deliver a strong seat to the rail.
e. Harmed cast iron sleepers can be remolded into new sleepers hence, the scrap value of cast iron is suitable.
f. The creep of rail can be discouraged by cast iron sleepers.
Disadvantages of Cast Iron Slippers
The disadvantages of cast iron are as follows:
a. Cast iron is breakable in nature and it can be harmed easily while managing. So, transportation, and placement are challenging to negotiate with.
b. Cast iron sleepers can be efficiently damaged and corroded by salt water so, they are not appropriate for coastal territories.
c. They may harm poorly when the derailment happened.
d. Cast iron is pricey in the market when compared to some other sleeper materials. Hence it is cheap.
e. So many fastening materials are needed to improve the rail to the sleeper.
f. Proper Maintenance is needed.
e. Composite Sleepers
Composite sleepers are modern type sleepers that are made from waste plastic and rubber. Hence, it is also called plastic sleepers. They have many combined properties of all other types.
Advantages of Composite Sleepers
a. Composite sleepers are serviceable for longer spans of about 50 years.
b. Composite sleepers are eco-friendly sleepers.
c. They are light in weight but possess great strength.
d. Their scrap value is good because of the recyclable properties of composite sleepers.
e. They can be resized effortlessly like wooden sleepers. So, they can be employed for any type of rail division.
f. Vibrations received from rails are reduced well by these composite sleepers.
Disadvantages of Composite Sleepers
The disadvantages of composite sleepers are as follows:
a. They are not that vastly suitable against fire.
b. The price of composite sleepers may expand for large-scale production.
This was for the Railway Sleepers.
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