How far should a portable changeable message sign (PCMS) be visible both day and night?

The visibility distance of a portable changeable message sign (PCMS) is critical for ensuring that drivers can read and comprehend the information presented on the sign in a safe and timely manner. A distance of 1/2 mile is typically recommended for visibility both during the day and at night due to several factors, including the size of the sign, the brightness of the display, and the speed at which vehicles travel.

At a distance of 1/2 mile, drivers have sufficient time to react to the information displayed, allowing them to adjust their driving accordingly, whether it involves slowing down, changing lanes, or following detour instructions. This distance strikes a balance between ensuring the sign remains legible while accounting for various driving conditions, such as light and weather.

Furthermore, signs must be positioned to ensure maximum visibility. This could include considerations like height and angle of the PCMS, as well as placement in relation to other roadside features. Thus, the recommendation of 1/2 mile is established as a standard to promote safety and effective communication to drivers.