Donkey or blackcurrant – The speed bump as seen in Unimat traffic is the oldest. It has a height of 10 cm and a length of 4 m. They are located in built-up areas, in areas or lanes limited to 30 km / h, rest areas, or forest roads.
It is forbidden to pass a pedestrian crossing on a speed bump. On the other hand, when they are of the trapezoidal type (larger and which extends over the entire road), they must have a pedestrian crossing.
To be visible day and night, they are announced by vertical and horizontal signage. Outside built-up areas, traffic signs are generally located 150 to 250 meters before the retarder. The regulatory ground markings for speed bumps of the speed bump are made up of 3 white triangles on each lane, the points oriented in the direction of traffic.
Also called Berlin cushion or Lyon cushion, these speed bumps are 6 to 7 cm raised trays with four oblique edges. Their shape and color distinguish them from the speed bump and make it particularly visible. They are found in built-up areas, on sections of track limited to 30 km / h, road or motorway rest areas, and in parking areas. They fit better into the urban landscape.
The marking on the ground of the Berlin cushions consists of 3 small triangles on the rising part, the points facing the direction of movement. For the right and left wheels to correctly mount on it, the vehicle driver is forced to descend to 30 km / h. Their size allows trucks and buses to avoid them. Cushions are particularly dangerous for two wheels because of their material and shape.
The soundtrack is similar to the speed of a donkey, but it is thinner and less high: 50 cm wide and about 1 cm high. Its particularity is that it emits a thudding noise each time a car passes by. They are usually grouped by 5 or 6 to have a real effect on the driver’s mind.
There are 2 types: those placed on highways or near tolls to ensure that users do not deviate from their route and soundtracks for private use, generally yellow and black, located in the car parks of shopping centers, hospitals, etc. No signs or markings on the ground announce them.
The niche (or chicane) takes the form of deformation of the road’s route; it forces you to slow down because of the two tight bends, all the more so for large-scale vehicles considered to be more dangerous. This type of retarder does not present any discomfort for the driver or risk for the vehicle. It is usually found near schools or crossroads instead of a straight line.
The lock is another version of the niche or chicane; it is materialized by a sidewalk projection, which delimits a 3.5 m roadway. Therefore, only one vehicle can pass at a time, and the one arriving in front must wait. The lock can be lined with cycle lanes so that two wheels do not have to go by road.
Apart from these conventional retarders, other signs such as those announcing a curve, two successive turns, or a narrowing of the roadway allow users to know that they have to adapt their pace. They can therefore also be considered as speed bumps.