What is the maximum number of lines that can be included in a phase on a Portable Changeable Message Sign?

The maximum number of lines that can be included in a phase on a Portable Changeable Message Sign is three lines. This design criterion is based on the need for readability and the ability to convey clear messages to drivers.

Using three lines helps keep the message concise while still providing enough space for important information, such as messages related to traffic conditions, detours, or warnings. This limitation is established to ensure that messages can be read quickly by motorists, who may only have a few seconds to glance at the sign while driving.

Signs with more than three lines could lead to confusion and increase the time needed for drivers to understand the message, impacting their reaction times and overall road safety. Thus, the three-line maximum strikes a balance between delivering sufficient information and maintaining clarity for effective communication with road users.