Road conditions for safe movement of the car (a part 2)

For the roads of I category which are passing on flat district, settlement speed taking into account movement safety makes 150 km/h, and for roads of II category - 120 km/h. The valid maximum speed taking into account intensity of movement and geometry of a line which can be almost realised, makes approximately 85% from the settlement.

On separate sites of some highways with optimum conditions for high-speed movement under the decision of local authorities movement with higher speed is authorised, than is established by Rules of traffic for all roads (90 km/h).

For the roads of III category which are passing on flat district, settlement speed of 100 km/h, and for lying on a cross-country terrain - 80 km/h. For roads of IV category these figures are accordingly equal 80 and 60 km/h. Thus, for many roads III and IV categories the greatest admissible speed for cars will be less than the top limit of speed established by Rules of traffic. On such roads the traffic signs limiting speed of movement are usually established.

Smoothness of a course and the minimum expenses of capacity for resistance kacheniju the car, especially at movement with high speeds, are reached on ideally equal and smooth road. Force of blow of wheels about roughness of road increases proportionally to a square of speed. Therefore, for example, at movement with a speed of 50 km/h separate roughnesses in height to 10 mm practically do not affect smoothness of a course of the car, at speed they cause of 90 km/h notable podbrasyvanie wheels. Certainly, a road surfacing not. Can be ideal, it always has roughnesses. But from the point of view of drivers these roughnesses should be such that pushes from them were completely absorbed thanks to deformation of tyres.

On the other hand, ideally smooth covering - a serious lack of road as thus the factor of coupling of wheels with road sharply decreases. Therefore the covering of highways should have a roughness with ledges and deepenings in 3... 5 mm. With such roughness of a covering the road visually is perceived as absolutely equal, and it is possible to consider it of to the greatest degree meeting the requirements safety and enough high comfortableness of movement.

The Road covering gets sometimes excessive smoothness owing to deterioration. As a result of long operation of a roughness are cut off by a friction of tyres about a road surface, and the factor of coupling of tyres with road on such covering sharply decreases. For restoration of former quality a covering strew melkorazdroblennym a stone material - klintsem, water with tar and slightly ukatyvajut road skating rinks.

It is necessary to consider that at once after such regenerative repair the covering delivers many troubles: badly rolled klinets it is pulled out from under wheels and often strikes blows to windshields and headlights of overtaken and counter cars. Therefore, on similar sites it is necessary to reduce speed, to maintain the big safe distance and to abstain from overtaking. After sufficient ukatki klintsa such surface of a covering provides the best coupling of wheels with road.

Decrease in factor of coupling conducts to dangerous sliding on roads with a new covering because of allocation of an oil film from asphalt.

Sites with the worn out and repaired covering vary often enough, and the driver should observe of road change constantly. To distinguish them from afar it is easy on colour: more dark repaired sites are well allocated on the general background in the summer, and old smooth sites look more light and give at bright solar illumination sharp reflexions.

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