Variable-message sign

The variable message signs ( VMS short ) is a special type of traffic sign, it can be shown that, amended or repealed if necessary. The representation of dynamic message signs used for road safety and traffic control on busy highways and motorways. Is controlled by the display of a traffic control center. There is monitored at selected locations the traffic situation and may, if appropriate, respond to events, such as an accident or traffic jam. In part there is the control, for example, upon the occurrence of poor visibility ( fog warning system ), automatically.

In addition to the dynamic display of traffic signs and signposts can be used as so-called variable message signs for use.

Technology

Generally, a distinction is made between mechanical variable message signs ( so-called " Prismenwendern " ) and light emitting variable message signs.

Mechanical variable message signs

In mechanical variable message signs, the picture change is achieved by the rotation of single or multiple coupled three-or four prisms, which are moved by a motor via screw or belt drive. So three or four different image positions are possible depending prism drive. The prisms can be placed horizontally and vertically and are, as a static traffic signs, covered with reflective foil. Such change indicators can be integrated into ground-breaking signage, for instance to display alternative routes when traffic congestion on the main line (called variable direction ).

Due to the low power consumption (power only required while an image ) mechanical variable message signs can be executed with photovoltaic energy supply.

Light emitting variable message signs

In light-emitting variable message signs displaying the characters through a variety of powerful LEDs - in older traffic signs by fiber optics with central halogen bulbs - realized. LED and fiber-optic cables are provided with an attachment lens, which focuses the emitted light to the road users. The strong luminosity ensures good visibility of traffic signs even when rainfall or fog.

VMS with halogen bulbs included i.d.R. two halogen bulbs and a failure monitoring, the lamp turns on the second failure of one light and a fault signal settles. In VMS LED light points of the various summarized in chains LED chains are alternately plugged, so there is no meaningful disfigured content can not be displayed comes to total failure of the VMS if individual LED strings and. Again, a monitoring of the LED strings prior art. A failure of one or more LED strings is signaled by the controller to the higher headquarters.

By deliberately turning on or off the LED traffic signs shown may be changed. Depending on the spatial arrangement of the LEDs only certain traffic sign or shown any symbols can be displayed (matrix display).

Use

Variable message signs are used either individually or in groups attached to various support structures. You are either on a gantry which spans the roadway, or on a pole at the side of the road. Addition to the presentation of road signs and related instruction texts ( variable message signs conditioning ) also guide and goal setting data ( variable direction system) are shown.

Mechanical variable message signs, due to the prism technology show only a few different information and are therefore suitable for example for use in variable message signs systems.

In the light-emitting variable message signs significantly more different types of information can be displayed. For use they usually come with line control systems that will be installed on freeway and expressway sections with high traffic density, before and in road tunnels or at motorway junctions. There help variable message signs to prevent accidents, to avoid congestion or to warn other events.

The information displayed will vary depending on the location. In Germany or Austria, for example, one typically uses the usual road signs, supplemented with references. In other countries, such as Italy, whole sentences with tips for safe drive, clues are often displayed on the queue lengths or border crossing wait times. These sets are often presented out of consideration for the tourism in the English language.

In Austria, LED traffic sign with vehicle detection and control software can be used as a warning system for risk reduction technically unsafe crossings, since they increase the attention.

Norms and Standards

  • Guidelines for traffic sign installations on federal highways ( RWVZ )
  • Advice for control models of traffic signs investments in extra urban areas
  • RVS 05:04:21 traffic management systems
  • SN 640873-1 Road vertical signs - Variable message traffic signs - Part 1: Product standard
  • SN 640873-2 Road vertical signs - Variable message traffic signs - Part 2: Initial type testing
  • SN 640873-3 Road vertical signs - Variable message traffic signs - Part 3: Factory production control
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