Text b. Highway network.

Read the text and answer the questions.

Roads which interconnect inhabited localities and industrial agricultural centres, linking them to freight handling stations for other means of transport, constitute the basic highway network. Persons and goods requiring to be transported between specific origins and destinations, the amount of goods depending on the requirements of the national economy and established trade relations, make up traffic streams.

While planning an effective automobile highway network it is essential, in the first instance, to take into account the main freight and passenger traffic streams in order to keep the costs down and to facilitate the delivery of goods. The framework of a highway network is a system of trunk roads designed for long-distance high-speed passenger and goods traffic, and connecting the main economic regions of the country with its basic economic centres.

When laying out a highway it is essential to maintain administrative, cultural and economic communications between various parts of the country.

The location of a highway network is a fundamental element of road planning, and is determined by the distribution of the country productive forces, the further development of which it must promote. However, the considerable amount of money already invested in road building makes the designer use the existing metalled roads.

In all projects concerned with the development of highway networks, therefore considerable attention must"⁵ be given to the reconstruction of roads in order to render them suitable for modern high-speed motor traffic.

1) What is the title of the text? 2) What is a traffic stream? 3) What is to be done in the first instance while planning an effective automobile highway network? 4) What is the framework of a highway network? 5) What is it essential when laying out a highway? 6) What is a fundamental element of road planning? 7) What is it determined by? 8) What makes the designer use the existing metalled roads? 9) What is the purpose of the reconstruction of the existing roads? 10) What information does the last paragraph of the text carry?

Text C. Highway network planning.

Read the text and say why maps are so important in planning a new road or rebuilding the existing one.

In planning a highway network or a route, highway planners must learn:

1. where people live, 4) where goods are produced,

2. where they want to go, 5) what markets the goods arc sent to, and

3. how they get there, 6) how the goods reach their final users.

Traffic counts tell how many and what kinds of vehicles travel on a road, and when traffic is heaviest. From these and other facts about the past and present, planners try to predict future growth in population and industry, changes in land use, and how such growth and change will affect highway needs.

Public participation in road planning is essential. In U.S. highway planners hold public hearings on most major highway projects. These meetings enable citizens to present their views before a project begins.

Before highway construction begins, planners must also prepare an environmental impact statement. The purpose of such a statement is to discover in advance all the possible good and bad effects that a new highway may have on the public and on the environment.

Highway engineers have drawn up standards for various kinds of roads, highways, and bridges. These standards govern the thickness and kind of foundation and surfacing for different kinds of traffic; the number of lanes needed; the sharpness of curves; and the steepness of hills.

In planning a new road or rebuilding an existing one, maps must be drawn if they are not already available. Aerial photography is widely used today for this work. These maps show the location of other roads, railroads, towns, farms, houses, and other buildings. They also show such natural features as rivers, lakes, forests, hills and the slope of the land. The types of soil may also be identified.

Using these maps, engineers locate new highways and make detailed drawings called plans. The plans show the exact boundaries of the right of way. This is land needed for road pavement, shoulders, ditches, and side slopes. The plans also show the exact location, grades, and curves of the pavement, and the location of bridges and culverts.

So highway planners study everything from the long-range needs of a country to a particular section of a single route. This planning determines what the highway needs of the region are and how these needs can best be fulfilled and paid for.

Text D. Characteristics of highway traffic.

Read the text and say how traffic intensity varies.

Vehicles traveling in the same direction constitute traffic stream. It is apparent that the greater the number of vehicles in a stream, the more severe will be the requirements to be satisfied by the road.

A traffic stream usually consists of many types of vehicles, traveling at different speeds and carrying various loads. However in order to determine the width of the carriageways and the overall width of the road, the total number of vehicles on the road at a given period is taken as the major design criterion.

The total number of vehicles passing through any section of a road in unit time (day, hour) is called the traffic intensity. Traffic intensity varies along each individual road section; it increases in the vicinity of towns, large inhabited localities and railway stations and is reduced along stretches of road some considerable distance from large towns and cities. The traffic intensity on a road does not remain uniform throughout the day. It decreases sharply at nightfall.

Traffic intensity is not the only basic traffic characteristic. To determine the pavement thickness and to design different structures one has to know not only the number of loads but also their wheel loads and overall dimensions of vehicles.

The maximum wheel loads and overall dimensions of single and combination vehicles are established the by State Standards.

Single and combination vehicles are divided into two groups. Group A includes vehicles operating on roads of classes I and II with improved pavements as well as on roads of other classes if they are specially designed for such vehicles. Group В includes all other single and combination vehicles.

All vehicles whose weight when loaded exceeds 1,5 tons must have wheels with pneumatic tyres, with a nfmt rwr&r Л ^ Vo/pm? fnr crrnnn A and 5.5 1co7cm2 for eroun B.

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Theory and practice show that a heavy-weight vehicle at one pass can do more damage to a road than the passage of a great number of lighter vehicles.

Section II. Grammar