What is one of the primary functions of changeable message signs?

Changeable message signs (CMS) are primarily designed to display variable information. These signs are crucial in providing real-time updates and alerts to drivers regarding road conditions, detours, speed limits, and other vital traffic messages. The ability to change the displayed information depending on current conditions is what differentiates changeable message signs from fixed information signs, which provide static data that does not vary according to situational changes.

By effectively communicating changing traffic conditions and instructions, changeable message signs help improve safety and enhance traffic flow by informing drivers of necessary adjustments in behavior or routes. This adaptability is essential during events such as road closures, accidents, or construction work, where timely information can prevent congestion and potential incidents.