A curb (South German, Austrian, Swiss edge stone , North German also called curb stone , or East German also called edge stone ) is a component from road and path construction . It is used to demarcate different sections of the road from each other and for attaching grass verge and the road - or roadside on . The curb height varies and is usually in the range from 5 to 12 cm, in the case of the high curb from 10 to 15 cm. In order to make it easier for cyclists and wheelchair users to cross, the curbs are lowered at intersections, as well as at property driveways.
In Germany, a distinction is made between different types of curbs, on the one hand according to the material from which they are made and on the other hand according to the shape and function of the curb.
As a rule, curbs made of concrete acc. DIN 483 (previously), new: DIN EN 1340 or natural stone produced, whereby natural stones (often granite ) are significantly more expensive than concrete stones . You can often find curbs made of plastic .
The curbs are distinguished not only according to their material but also according to their shape, i.e. their purpose. The so-called asphalt border has a special position . It consists of asphalt mix with little voids and a hard binder and is installed in the course of the construction of a road. It is not made up of individual stones, but is part of the roadway.
Types of curbs and their uses
A high curb is a curb between 15 and 18 cm wide and 25 to 30 cm high, which separates the roadway as the area used by motorized traffic from the areas for pedestrians . It serves to protect pedestrians from traffic. For this purpose, it is usually installed in Germany and its neighboring countries in such a way that there is a difference in height of 10 to 15 cm between the roadway and the sidewalk . So that the tire is not damaged when driving against the curb or when parking on the sidewalk, the high curb is inclined in the area of the upper half; in Austria at least its edge is broken.
A round curb is also between 15 and 18 cm wide, but mostly only 18 to 22 cm high. It serves to lower pedestrian crossings and property driveways in the course of a high curb. Since it can be driven over at property driveways and it still has a difference in height at its front edge, it is rounded on the side facing the roadway.
At pedestrian crossings in Germany, the round kerbstone is usually installed with a height difference of 3 cm. This is to ensure that a wheelchair user can still run over it and a visually impaired person can still feel it.
- 20 cm × 10 cm with a 5 cm view (old name: F5)
- 20 cm × 20 cm with 7 cm view (old designation: F7)
- 25 cm × 20 cm with 10 cm view (old name: F10)
- 30 cm × 25 cm with a 15 cm view (old name: F15)
The low kerbstone is between 5 and 10 cm wide and between 15 and 50 cm high. It is used to delimit sidewalks and private properties or to delimit paths in gardens, parks or sports fields . The terms grass curb , lawn edging stone or border stone sometimes used for this are incorrect. The smallest variant, less than 6 cm wide, is regionally known as a snake.
The Buskapstein (from Buskap ) is a special curb designed to reduce the level difference between the bus stop and the bus boarding point. As a variant of the “high curb”, it should enable bus and tram passengers to get on and off without a difference in height. It has a height difference of 18 cm between the roadway and the sidewalk. A smooth run-up (climbing protection) directed towards the road is intended to prevent the arriving bus from getting onto the sidewalk when it touches the curb. In addition, the ground flank also reduces wear on the tire flanks. Due to the difference in height, it is also often used in places where parking on the sidewalk should be prevented.
So-called transition stones are available for better connection of different types of curbs. They bridge the height offset between normally offset and lower offset kerbstones (e.g. to allow better access to a property). Regionally, transition stones are also referred to as "wing stones", "sinkers" or "hangers".
For special applications (e.g. slight inclination of the road) there are slot or box channels with molded curbs. These then fulfill both the function of street drainage and that of the curb.
There are also roll-up shelves (e.g. Kassel roll-up shelves) for crossing points for cyclists, strollers, walkers, wheelchairs, etc., which, with a width of 25 to 30 cm, bridge a height difference of 3 cm. So that the visually impaired can see the lane boundary, the stones are white and have a tactile structure.
Installation of the curbs
The curb is placed in a concrete bed during installation in order to permanently achieve a secure stand and an even height. Curbs of high stability are given a back support made of concrete, which is intended to prevent the stone from falling or breaking away when driven over. Similar designs are also in use elsewhere, e.g. B. in cemeteries , or the so-called. Bounce stones (wheel deflectors) to protect the masonry of house entrances.
In some other countries (e.g. in North America), instead of the shaped stones customary in Europe, the curbs are made on site by hand or with the help of sliding formwork.
Special radius stones are available for tight curves. Larger radii are made from whole (1 meter long) or half straight stones. With the radius stones, a distinction is made between inner and outer arches.
Examination of the curbs
The curbs are usually tested with (servo) hydraulic, regulated testing machines. The force measuring range should be at least 150 kN and the control accuracy should range from 1% down to 1% of the total measuring range. Often a second test frame is required to be added to the already existing compression testing machines, the maximum load of which is 2000 or 3000 kN or even higher. When purchasing new testing machines, the connection of a 2nd test frame should always be provided in order to be prepared for future testing tasks. Special devices are offered by the individual manufacturers.