Editing Variable-message sign (section)

==Usage==
[[File:Variable message sign.jpg|alt=Variable Message Sign|thumb|A variable-message sign.]]
Early models required an operator to be physically present when programming a message, whereas newer models may be reprogrammed remotely via a wired or wireless network or cellphone connection.{{citation needed|date=May 2015}}

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, and in some states, [[Silver Alert|Silver]] and [[National Blue Alert Act of 2013|Blue]] 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.

Typical messages provide the following information:

*Promotional messages about services provided by a road authority during non-critical hours, such as [[carpool]]ing efforts, [[travelers' information station]]s and [[5-1-1]] lines
*Crashes, including vehicle spin-out or rollover
*Road Works
*Incidents affecting normal traffic flow in a lane or on shoulders
*Non-recurring congestion, often a residual effect of cleared crash
*Closures of an entire road, e.g. over a mountain pass in winter.
*Exit ramp closures
*[[road debris|Debris on roadway]]
*Vehicle fires
*Wildfires
*Short-term maintenance or construction lasting less than three days
*Pavement failure alerts
*[[Amber alert|AMBER]], [[Silver Alert|Silver]], and [[National Blue Alert Act of 2013|Blue Alert]]s, as well as weather warnings via the warning infrastructure of [[NOAA Weather Radio All Hazards|NOAA Weather Radio]]'s [[Specific Area Message Encoding|SAME]] system
*Travel times
*Variable [[speed limit]]s
*Car park occupancy levels
*[[speed sign]], for recommending a speed to approach the next traffic light in its green phase.

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 motorists' route selection, reduce travel time, mitigate the severity and duration of incidents and improve the performance of the transportation network.

===United Kingdom===
<gallery mode="packed" heights="100" caption="Examples of variable message signs in the UK">
File:UK traffic sign 6001.jpg|Temporary advisory speed limit of 50 mph.
File:UK traffic sign 6006.10.jpg|End of temporary restrictions.
File:UK traffic sign 6006.5.jpg|Lane 2 is closed ahead.
File:UK traffic sign 6006.1.jpg|Lane 2 and 3 are closed ahead.
File:UK traffic sign 6006.3.jpg|Lane 1 is closed ahead.
File:UK traffic sign 6006.7.jpg|Lane 1 is closed ahead.
File:UK traffic sign 6003.jpg|Leave the motorway at the next junction.
File:UK traffic sign 6006.4.jpg|Both lanes are closed.*
File:UK traffic sign 6006.2.jpg|All three lanes are closed.*
File:UK traffic sign 6006.6.jpg|All 4 lanes  are closed.*
File:UK traffic sign 6006.8.jpg|Risk of ice ahead.
File:UK traffic sign 6006.9.jpg|Risk of Fog ahead
File:UK traffic sign 6031.1.jpg|Do not use the lane below the signal.
</gallery>
<nowiki>*</nowiki> Do not enter the motorway when the red lamps are flashing in pairs from side to side.

On 27 March 1972, the first motorway computer-controlled warning lights in the UK, with 59 miles on the M6 from [[Broughton, Lancashire]] to [[Barthomley]], on the Cheshire boundary, and 26 miles on the M62 east of Whitefield, was switched on by [[Michael Heseltine]] and [[Baron Grey of Codnor|Charles Legh Shuldham Cornwall-Legh, 5th Baron Grey of Codnor]] at the headquarters of [[Cheshire Constabulary]] on Nuns Road.<ref>''Birmingham Daily Post'' Tuesday 28 March 1972, page 7</ref><ref>''Chester Chronicle'' Thursday 30 March 1972, page 2</ref>

It was centred at a police computer centre at [[Westhoughton]], that connected to police stations in Preston and Chester. The Chester site was soon be connected to the M53 and M57.<ref>''Cheshire Observer'' Friday 31 March 1972, page 21</ref> Four other regional computer centres would be opened at Perry Barr near the M6, [[Scratchwood]] near the M1, at [[Hook, Hart|Hook]] near the M3, and at [[Almondsbury]] near the M4. Most British motorways would be covered by 1975. The system was designed by GEC and had taken five years to design.<ref>''Times'' Tuesday March 28 1972, page 5</ref>