Variable-message sign

Such signs warn of traffic congestion, accidents, incidents such as terrorist attacks, AMBER/Silver/Blue Alerts, 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, inform of the traffic conditions, or display general public safety messages.

In recent years, some newer LED variable message signs have the ability to display colored text and graphics.

[citation needed] A complete message on a panel generally includes a problem statement indicating incident, roadwork, stalled vehicle etc.

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.

Increasingly, signs have been used to remind drivers to buckle seat belts ("Click it or ticket"), obey the speed limit, and stay off the road if impaired ("Drive sober or get pulled over").

[7] Examples[7][9][10][11][12][13][14] of humorous signs seen in New Jersey, Arizona, Texas, Pennsylvania, Delaware, Iowa, New York, Minnesota and Ohio include: In 2024, concerns that these messages were distracting drivers led the Federal Highway Administration to strongly discourage signs with "obscure meanings, references to pop culture" or humor.

An optional third truck, the team leader, may be utilized for driving by and monitoring the incident itself, traffic patterns and delay times, to make strategic decisions for minimizing delays—analogous to spotter planes used in fighting forest fires.

Trailer-mounted VMS can be equipped with radar, cameras, and other sensing devices as part of a smart work zone deployment.. A variable-message sign figures significantly into the plot of the 1991 film L.A. Story.