What Are Arrow Boards?
An arrow board is a lighted display, usually trailer-mounted, that uses arrows or patterns to direct drivers to merge or shift away from a closed lane. It is commonly used for lane closures. The arrow board gives drivers an early, highly visible cue about which way to move.
Last updated: June 24, 2026
Why It Matters
On higher-speed roads, an arrow board is often what alerts drivers to a merge from a distance. The wrong mode or a poorly placed board can send a confusing message.
Used correctly, it reinforces the lane closure together with signs and channelizing devices.
Where It Shows Up in the Field
Arrow boards appear at lane closures, especially on multi-lane and higher-speed roads such as Southern California arterials and highways.
In the field, the board is positioned so drivers see it in time to merge smoothly.
Common Mistakes
- Using an arrow board where a closure does not call for one, which can confuse drivers.
- Setting the wrong display mode for the situation.
- Placing the board where it is seen too late to merge.
- Leaving the board active when the closure is not in place.
What to Check Before Work Begins
- That the arrow board is used where the plan specifies.
- That the display mode matches the closure.
- That it is positioned for enough merge distance.
- That it is turned off or removed when not needed.
Related Terms
Related Pages
Frequently Asked Questions
When is an arrow board used?
An arrow board is commonly used for lane closures, especially on higher-speed roads, to direct drivers to merge or shift away from a closed lane.
Where should an arrow board be positioned?
It is placed so drivers see it in time to merge smoothly, with enough distance ahead of the closure for the conditions and speed.
Should the arrow board run when the closure is down?
No. The board is turned off or removed when the closure is not in place so it does not give a misleading signal.
Need Project-Specific Support?
Work Zone Compliance provides general educational information about work zone compliance. For project-specific traffic control plan support, permit coordination, or public right-of-way planning in Southern California, visit Public Ready.
Visit Public Ready