Various types of sleepers

Sleepers originally consisted of slabs of stone or longitudinal bulks of timber laid under the rails. Both these types were discarded, as in the first case the running was rough and the noise was very great. Longitudinal sleepers were found to be expensive as they had to be of a large section to satisfactorily support the rail and the cost of timber increases rapidly with increase in section.

Cross sleepers, which were first introduced in 1835, are now employed universally. They are made of wood, steel, cast iron or concrete. A sleeper that fulfils all requirements most satisfactorily is the wooden sleeper. As the number of sleepers required is enormous and as timber is becoming scarce, sleepers of other materials are being used in increasing numbers in many countries. Metal sleepers have been used on a large scale in countries where deterioration of wooden sleepers due to the presence of vermin, e.g. white ants. and on account of climatic conditions is rapid. In Britain, treated wooden. sleepers last about 20 years in the main tracks and then give further service in siding, whereas the life of wooden sleepers in India is considered to be 15 years. Cast iron sleepers, although used extensively in India and South America, are little used elsewhere. Concrete sleepers both of the reinforced block type and the prestressed concrete type are being used increasingly in Europe. They have all the advantages of a material which is immune to corrosion and vermin attack.

Vocabulary

treated wooden sleepers – оброблені дерев’яні шпали

reinforced block – залізобетонний блок

prestressed concrete – попередньонапружений бетон

Дати письмову відповідь на запитання

1.What ·did sleepers originally consist of?

2.Why were these types discarded?

3. What sleepers are now employed universally?

4. What materials are sleepers made of?

5. Where are metal sleepers used?

6. What types of concrete sleepers are used in Europe?