The main determining factors in the construction of roads are the intensity of vehicle traffic, speed and axle load. Depending on this, the width and pavement are designed . Categories of roads are established by a combination of the following indicators: actual and reduced traffic intensity, number of lanes, speed, lane width, width of the dividing strip, width of the reinforcing edge strip, subgrade width, maximum longitudinal slope, curve radius in a turn. The main categories of roads in the Russian Federation are I, II, III, IV, V.
Categories I and II of roads are assigned to sections with a capital type of coverage, which include various roads having from one to several lanes in each direction. They are designed for speeds up to 120 km / h (1a - up to 150 km / h), cars with an axle load of up to 10 tons can move along them, they have wide stripes (3.75 m), maximum slopes are limited to 3-4%, radii turns up to 1200 m.
Wide shoulders and dividing strips (only for the I category of roads) provide safety and necessary throughput. The maintenance of roads of this category includes a wide range of works, in particular, for the I and II category of roads, snow is cleared, icing is cleaned, since traffic on them is carried out all year round.
For category III roads, where traffic is less intense, a lightweight improved pavement is set up. They allow strip widths of up to 3.5 m and turning radii of 600 m, their maximum slope can reach 5%. But at the same time, vehicles with an axial load of up to 10 tons can move in sections of category III. The estimated speed mode for them is no more than 100 km / h, the number of lanes in each direction is no more than two.
Category IV includes paved roads, but it may not have improvements (gravel, cobblestone). The width of the lanes on them is not more than 3 m, the maximum of longitudinal slopes can reach 6%, the minimum turning radius is 250 m. The maximum axial load is 6 tons, they should be cleaned in winter, but a layer of ice and snow can be left on the coating.
If the roads do not have improved coverage, in the spring they may be subject to restrictions on the movement of vehicles of a certain carrying capacity. The reason for this lies in the fact that in the spring due to the great moistening of the roadway, its supporting ability decreases, and under the action of a certain axial load, deformation of the pavement can occur. If the restriction is not introduced, then in the spring you should carefully drive along such roads, taking into account the fact that rolling friction can constantly change due to nerves and cracks, which complicates the operation of the machine.
Category V includes roads that do not have hard surface (laid on ordinary soil). To increase the stability of the upper layer, their surface is sometimes treated with special binding additives. During the thaw period or during heavy snowfalls, the cessation of movement is allowed on them. As a rule, they have only one lane; the calculated speed on them does not exceed 60 km / h.