When driving along the crooked section of the road, the rear wheels of the car walk along the arc with a circular curve of a smaller radius than the front wheels. Therefore, in crooked areas, a bruise of the carriageway is required.
When driving along the crooked sections of the road, a centrifugal force occurs, under the influence of which the car is possible, t. e. side sliding, and sometimes carbing of the car. To prevent the indicated phenomenon, the external edge is increased against the internal edge of the road, giving the roadway of the road a single -shoe transverse profile instead of the usual sections of the path of a gable.
The elevation of the outer edge of the road on the curves is called a turn. The larger the size of the radius of a circular curve, the better the conditions of the car on the road. By calculation, a dependence between the speed of the car, a radius of a circular curve, a coefficient of friction of the wheel of the car when moving on the road coverage and a transverse slope of the carriageway, is established.
The plus sign is introduced when the turn is arranged, and the sign is minus – without a turn device. The longitudinal profile is a section along the axis of the road with the strokes of the distances between the points of the terrain fractures, the markings of the terrain, the design line of the road, the heights of the embankments and the depths of the recesses. The longitudinal profile for roads is drawn on millimeter paper on a scale: for access roads – horizontal – 1: 5 000, vertical – 1: 500; for intra -construction tracks – horizontal – on the scale of the plan, and vertical – 10 times more.
The design line applied to the longitudinal profile belongs to the edge of the subgrade. Longitudinal slopes of roads depend on the category of road and the type of carriageway. Fractures of the design line, if the bisector of the angles formed by these fractures in the vertical plane, more than 5 cm, are mating in circular curves.