Speed reducer

A speed reducer is a term designating a family of road devices obliging the motorist to slow down and thus to redouble prudence. In the language running, speed reducer means back of ass or blackcurrant (see below).

The speed reducers are placed at the accesses of the schools, of the places where there already were deaths, but also in the coasts and the descents, in the straight lines.

There do not exist on Autoroute.

Types of speed reducers

the back of ass is oldest of the speed reducers. It is simply a small bump narrow and perpendicular to the street, more or less important height which obliges the driver to reduce its speed not to make a jump . In France, it is interdict to set up a crossing for pedestrians above.

the blackcurrant often lies between two back of ass but is its opposite: it is a hollow of the road which also obliges to slow down (not to be confused with the Pothole which is due to him to a bad maintenance of the Voie).

the soundtrack , as its name indicates it is a band perpendicular to the Voie like the back of ass but much finer and less high. Its characteristic is to emit a deaf noise with each passage of an axle of car (from where their qualification). They are in successive groups from 3 to 6 to be able to make effect in the spirit of the driver.

the cushion of Berlin (or Berliner Cushion ) is rather recent and is the special shape of the back of ass: it is an elevated square plate (often white to locate it) posed on 1 way at the same time (if the road is with double-direction, there are of them two, etc) with 4 oblique edges. It obliges the driver of a light vehicle to slow down massively because the wheels must go up correctly on the terminal. The driver of a heavy vehicle can on the other hand avoid the terminal if the diameter of the axles is larger than the side of the plate installed.

the crenel , is a short but voluntary deformation road alignment. A way in straight line is replaced especially with the accesses of the schools by a crenel of about fifty meters approximately. It obliges to slow down because of the two tightened turnings, therefore increases safety, but makes difficult its use for heavy vehicles.

the curve tight, simple but effective, is another voluntary deformation of the road, with the accesses of the Carrefour S for example to oblige the motorist to slow down to avoid undergoing the force Centrifuge.

Lastly, the roundabout , the Gyratory or the installation of a central small island at a precise place makes it possible to reduce speed and enters within the framework of the speed reducers.

Homologation and standards in France

The decree n°94-447 of May 27th, 1994 (NOR: EQUS9400480D) described in a very precise way standards to be respected for certain devices of the speed reducer type. Standard NFP 98-300 of May 16th, 1994 could also be consulted.

It should be noted that the devices of the type Berliner cushion do not appear in the decree.

In a more general way, it is up to the commune of check the homologation of the device which she wishes to install and check her conformity to the standards for the choice of her establishment, and during construction. Indeed, the responsibility for the mayor could be required in the event of accident caused by a device not respecting the regulations in force (source: Written question n° 20309 of Mr. Henri de Raincourt published in the OJ Senate of the 2/6/1997 - page 334).

Nds-nl: Verkeersdrumpel

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