Arrow Board or Message Board? Picking the Right Signal

Arrow boards and changeable message boards do different jobs in a work zone. Here is how to choose, plus notes on lamp counts and ballast certification.

Arrow boards and changeable message boards are not interchangeable. One tells drivers which way to move; the other tells them what is going on. Picking the right signal, and configuring it correctly, is part of keeping a work zone readable at highway speed.

What each one is for

• Arrow boards: direct traffic to merge left or right, or flash a caution pattern. They come in 15-lamp and 25-lamp configurations.
• Changeable message boards (CMS): display text like reduced speeds, lane closures ahead, or detour information.
• Use an arrow board when the message is a lane change; use a CMS when drivers need context before they reach the taper.

Sizing and certification

A 25-lamp board reads at greater distance than a 15-lamp board, which matters on faster roads. For portable boards, check the ballast requirements. NJ ballast certification is a common reference point, and getting it wrong means a board that can tip or fail to meet spec. Match the board size to the road speed and confirm the ballast is certified for your application.

Can a crash truck carry an arrow board?

Yes. Many TMAs are built with an integrated arrow board so the shadow vehicle signals the lane change and absorbs impacts in one unit.

Do I need both an arrow board and a message board?

Often, yes. The message board sets expectations upstream, and the arrow board delivers the final merge instruction at the taper.