Cars in our country are maintained in various climatic and road conditions. It and advanced roads of cities, highways, roads with a firm covering and without it, and frequently and full impassability. Many roads are laid in mountain areas of the country.
In the climatic relation is a frigid climate of northern areas with the long period of operation in the conditions of snowfalls and ice, and also in the conditions of a hot climate of southern areas and areas of Central Asia. Such variety road and environmental conditions demands from drivers of cars of many-sided skill and its constant perfection. Especially it concerns drivers who maintain cars in sharply varying conditions when it is required to estimate operatively changed conditions and to take necessary measures for movement safety.
From the road conditions characterised by a technical category of road, the mode of operation of the car depends.
The Road (fig. 56) can have some travellers of the parts which are differentiated by dividing strips or being at different levels. The top layer of road name a covering. He creates an equal surface on road and provides coupling of tyres with road.
a Fig. 56. Road elements: 1 - passing a part, 2 - a road cloth, 3 - an alignment strip, 4 - a roadside, 5 - a ditch, 6 - a sawn-off shotgun, 7 - brovka, 8 - a road axis
Distinguish some types of coverings, and the best, but at the same time and the most expensive, are capital improved tsementobetonnye or asfaltobetonnye. An advanced capital covering are also roadways from stone bruskov the correct form (a stone blocks or a mosaic) or an artificial stone material (a special brick - klinkera). The advanced facilitated coverings produce from rubble or the gravel processed by knitting materials.
Other kind of coverings - transitive. It concern shchebenochnye and gravijnye highway, the coverings made of slags, and roadways from bulyzhnogo or a chipped stone. In certain cases transitive coverings carry out from gruntov, processed by liquid knitting materials: organic oil bitumens, coal tars or cement and izvestju.
Soil coverings arrange from gruntov, others improved by additives gruntov (for example, in clay grunty add sand, and in sandy - clay, loamy or peat grunty).
For carriageway strengthening, and also for a short-term stop of cars and movement of pedestrians near to proezzhej a part do roadsides 4. To allocate and strengthen towering over proezzhej a part separate elements of road - dividing strips, sidewalks, islets of safety, a stop of buses, etc., arrange borders.
Roadside ditches - ditches 5 - serve for water drainage from a road cloth (proezzhej parts and roadsides).
Any longitudinal strip proezzhej parts in width, sufficient for movement of cars and other not rail vehicles (except motorcycles) in one number, is called as a lane. It is defined by dimensional width of the car or other vehicle and additional strips from both parties, named backlashes of safety (equal intervals between boards of cars). The Lane can be in certain cases designated a longitudinal marking 8.
The above settlement speed of movement - speed limit which can develop the single car on the constructed road, - the there should be a width of backlashes of safety and the general width of a lane more.
In our country all highways share on five categories. Are expensive I and II categories with capital types of coverings answer conditions of automobile movement more full. To their number carry, for example, new highways with several lanes in each direction and two-way, having on one lane in one party. Wide lanes (3,75, the limited maximum biases (3... 4%), the increased radiuses of turn and the widened roadsides provide traffic safety and sufficient throughput on these roads.
III categories calculated on less heavy traffic Are expensive, have the facilitated advanced covering. The width of each lane of such road can be reduced to 3,5 m, radiuses of curves in the plan to 400 m, the maximum biases TO 5%.
Roads concern IV category with a firm covering, but not always improved (a cobble-stone, gravel). Width of a lane on them no more than 3 m, the minimum radiuses of turns of 250 m, as much as possible longitudinal biases of 6%.
V category concern profilirovannye the roads which do not have a firm covering (passing on a natural ground). Sometimes their surface process the special additives binding a ground, and a little raising firmness of the top layer.
In an autumn and spring impassability of roads, and also in snow drifts they usually become impassable, but in the beginning of winter, with approach of the first frosts and to strong snowfalls, and also in the summer during dry time dirt roads possess high qualities for operation.
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