What are Railway Sleepers and What is their purpose?

Railway sleepers, also called railroad ties, railway ties or crossties, are an important railway component. Generally, the rail sleeper is always laying between two rail tracks to keep the correct space of gauge. In the recent time, concrete sleepers are widely used, especially in Europe and Asia. And in UK, steel ties are common. Besides, plastic composite ties are also employed in the rail track transportation.


History

n 1877, Joseph Monier, a French gardener, suggested that concrete reinforced with steel could be used for making sleepers for railway track. Monier designed a sleeper and obtained a patent for it, but it was not successful.

Concrete sleepers were first used on the Alford and Sutton Tramway in 1884. Their first use on a main line railway was by the Reading Company in America in 1896, as recorded by AREA Proceedings at the time. Designs were further developed and the railways of Austria and Italy used the first concrete sleepers around the turn of the 20th century. This was closely followed by other European railways.

Major progress was not achieved until World War II, when the timbers used for sleepers were scarce due to competition from other uses, such as mines. Following research carried out on French and other European railways, the modern pre-stressed concrete sleeper was developed. Heavier rail sections and long welded rails were also being installed, requiring higher-quality sleepers. These conditions spurred the development of concrete sleepers in France, Germany and Britain, where the technology was perfected.

The 1 ft 11 1⁄2 in (597 mm) gauge Lynton and Barnstaple Railway (1898 to 1935) in North Devon, experimented with concrete sleepers at a number of locations along the line. As the sleepers were cast to gauge, they were of little use outside the station areas on this very curvaceous line where gauge slackening was commonly required. They were also noisy and lacked the elasticity of wooden sleepers creating a very rigid road. Some of those concrete sleepers can now be seen on display at Woody Bay Station.

Interest in concrete railway sleepers increased after World War II following advances in the design, quality and production of pre-stressed concrete.

Chaired bullhead concrete sleepers have been around since at least the 1940s; the Great Western using a two-holed chair, thus saving both scarce wartime timber and steel fixing bolts.This design was used by the government-run railways during World War II and in particular immediately prior to D-Day when timber was scarce and track extension or replacement was urgently required. Gravesend West Street station was thus relaid in 1944 to enable the huge increase in freight to be handled.


Indian Railways proposed to use ferro concrete sleepers in large yards. Ferro concrete sleepers only trial was made in 1949 in the Langhola Ghat section of the Sealdah Division in Indian railways. ere there are very many difficulties. For instance, they are heavy and each weighs about 6 mds. The handling difficulty, the difficulty about fastenings, packing are all there unsolved. They have to be experimented on a large scale before any definite opinion is given about them. 

Types Of Railway ðŸš‚ Sleeper

1.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, teakwood are more famous.

Advantages of wood rail sleepers

  1. Easy to handle (Moderate weight and not easily susceptible to damage).
  2. Lower producing cost.
  3. Good dampening property: absorbs vibrations.
  4. Gauge adjustment is easier.
  5. Good track circuiting (electric insulation) quality.

Disadvantages of wood rail sleepers

  1. Short lifespan (12-15years).
  2. Difficult to maintain gauge (hole widening problem).
  3. Negligible scrap value.
  4. High maintenance cost (Fire hazard and pest attack).
  5. Higher probability of theft due to high opportunity cost.
  6. Light weight makes it unsuitable for fast track.

2.Concrete Sleepers

Concrete sleepers have many advantages like longer lifespan, high stability, small maintenance, low damage rate and low scrap rate. They are widely used in high speed railway and the stability is much higher than wood sleepers. Many countries chose concrete sleepers to build high speed passenger line. While concrete sleepers still have many disadvantages like heavy weight, difficult to transport and environment limits. They are not suitable for frozen earth, heavily polluted area and busy routes of mineral.

Advantages of concrete rail sleepers

  1. Suitable for modern methods of track maintenance.
  2. Easy to maintain gauge, cross level and alignment
  3. Offer higher longitudinal and transverse stability.
  4. Can be used in track circuited areas.
  5. Suitable for mass production with locally available materials.
  6. Longer life (40-50years) allows renewal of both rail and sleeper together.
  7. Not susceptible to (corrosion, fire hazards and pest attack).

Disadvantages of concrete rail sleepers

  1. Damage is heavy at the time of derailment.
  2. Track laying needs mechanical method.
  3. Heavy to handle.
  4. Have no scrap value.

3.Steel Sleeper

Steel rail sleepers are often seen as a middle ground between wood and concrete. Sturdier than wood and less expensive than pre-stressed concrete, it seemed logical that steel could prove a boon to companies looking to undertake an economical track upgrade. Indeed, in some areas steel ties are still performing adequately after 50 years of service. A lesser reliance on ballast (approximately 60% less than required for concrete; 45% less than wood) also seems to tip the scale in steel's favors, especially in areas where timber is scarce.

Advantages of steel rail sleepers

  1. Longer lifespan (30-40 years)
  2. Easy to maintain gauge
  3. Ensure the smooth of railway transportation
  4. Lesser damage during handling and transport
  5. Have good scrap value
  6. Not susceptible to fire hazards or vermin attack

Disadvantages of steel rail sleepers

  1. Unsuitable for track circuiting areas
  2. Corrosion prone
  3. Gauge change is not possible
  4. Light weight (80kg) and not suitable for fast track
  5. Develops cracks at rail sseats

4.Composite Sleeper

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 of Composite Sleeper

  1. Composite sleepers are serviceable for longer spans about 50 years.
  2. They are light in weight but possess great strength.
  3. Composite sleepers are eco-friendly sleepers.
  4. Their scrap value is good because of recyclable property of composite sleepers.
  5. Vibrations received from rails are reduced well by these composite sleepers.
  6. They can be resized easily like wooden sleepers. So, they can be used for any type of rail section.

Disadvantages of Composite Sleeper

  1. Composite sleepers are not that much good against fire.
  2. The cost of sleepers may increase for large scale production.