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?

5. Length of rail

The length of rails varies considerably in various countries. As the rail joint is the weakest part of a track structure, its strength being about one half that of the rails, it would appear to be desirable to use as long a rail as possible. Wear and tear of vehicles would be decreased and comfort of passengers would be increased if longer rails were used. The length of a rail ,is however governed by the length which can be produced at a reasonable coat by the manufacturers. A further limiting factor is the transport of rails. Rails have to be of such lengths that they may be carried in the longest standard wagons. Very long lengths of rails have been transported but a series of special wagons are required for such ~ feat with resultant increased cost. Again. very long rails cannot be handled by manual labour and special handling devices. such as cranes, are necessary.

The advantages of fewer joints are so great that the practice of joining the rails together by welding is on the increase. Welding the ends of adjacent rails overcomes many of the disadvantages of long rails, particularly those of manufacturing und handling. The rails are welded together after laying by one of a number of methods.

Vocabulary

length of rail – рейкова пліть

rail joint – рейковий стик

feat – справа

expansion gap – зазор між рейками

Дати письмову відповідь на запитання

1.What part of the track structure is the weakest?

2.What would passengers and vehicles gain if longer rails were used?

3.What is the length of the rail governed by?

4.How can very long lengths of rails be transported?

5.What practice overcomes disadvantages of manufacturing and handling long

rails?

6. Block system

It was necessary for railroads to utilize some means of spacing trains at safe distances and to provide them with a clear track. The method now generally in use to accomplish this purpose is called the block system. A block is a length of track of definite limits, governed by block signals.It is possible for trains to pass through the blocks, and through the several sets of signals constituting each block as rapidly as considerations of safety warrant with regard operating conditions, speed of trains, and the braking distance required.

Block signals are considered to be now largely under electric control. Further developments in connection with the control of train movements are systems of centralized traffic and interlocking plants at intersections.

A system of centralized traffic control (CTC) centralizes dispatching at a given point, where a dispatcher controls train movements over an extensive area.

An interlocking is an arrangement of signal appliances so interconnected that their movement must succeed each other in predetermined order. This prevents two trains from receiving a proceed signal at the same time at railway crossings.