A variable (also changeable, electronic, or dynamic) message sign, often abbreviated VMS or CMS, is an electronic traffic sign often used on roadways to give travelers information about special events. They warn of traffic congestion, accidents, incidents, roadwork zones, or speed limits on a specific highway segment. They may also ask vehicles to take alternative routes, limit travel speed, warn of duration and location of the incidents or just inform of the traffic conditions. A complete message on a panel generally includes a problem statement indicating incident, roadwork, stalled vehicle etc; a location statement indicating where the incident is located; an effect statement indicating lane closure, delay, etc and an action statement giving suggestion what to do traffic conditions ahead. These signs are also used for AMBER Alert messages.
In some places, VMSes are set up with permanent, semi-static displays indicating predicted travel times to important traffic destinations such as major cities or interchanges along the route of a highway.
VMSes were deployed at least as early as the 1960s. The current VMS systems are largely deployed on freeways or trunk highways.
Typical messages (such as those stipulated by the Minnesota Department of Transportation) provide the following information:
Crashes, including vehicle spin-out or rollover
Stalls affecting normal flow in a lane or on shoulders
Non-recurring congestion, often a residual effect of cleared crash
Closures of an entire road
Downstream exit ramp closures
Debris on roadway
Vehicle fires
Short-term maintenance or construction lasting less than three days
Pavement failure alerts
The information comes from a variety of traffic monitoring and surveillance systems. It is expected that by providing real-time information on special events on the oncoming road, VMS can improve vehicles' route selection, reduce travel time, mitigate the severity and duration of incidents and improve the performance of the transportation network.
Aesys is a world leader in LED display, LED signs and VariableMessageSigns (VMS).
These led signs can be used for general information, lane control signs (LCS), parking guidance, traffic status, hazard warning, speed advice (variable speed limit signs VSLS) etc. Trailer mounted portable DMS are also available.
Using Aesys' extensive knowledge and experience, electronic signs can be provided for both on-board systems (led destination sign, bus shelter LED signs, vocal announcement system, next-stop information system, follow-me LED sign) and stationary systems (arrival-departure LED display, vehicle monitoring system VerbaFleet, bus shelter LED sign, check-in LED display for airport)...
The sign shown in Figure 1 of this report is somewhat unusual in that it is an on-premise sign adjacent to an Interstate highway, and it possesses all three of the display characteristics discussed here.
Often these signs have taken the form of variable-message displays, in which the factors of color, brightness, contrast, and message length (to name a few) could be varied along with the presentation of a virtually unlimited variety of alphanumerics and graphics.
In this respect, message center signs in shopping center plazas, where density and variety of signs attached to structures often are controlled by the landowner/landlord's architectural design concept or a local sign code, may not be typical of the major use that is to be made of this type of sign.
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