Traffic Message Boards and What They Are?

A lot of people do not know what traffic message boards are.  Well, they are those blinking signs on the side of the highway, those large boards that have messages on them, telling you to slow down or that traffic is near.  Sometimes they care called arrow boards or advisory arrows.

Traffic message boards can be attached to trailers, mounted on trucks, or just simply sit there on the side of the highway.  Something not known about a traffic message board (at least not commonly known) is that it can cost as much as $20k.  Some of them have laptops to help with putting up the message.