Red regulatory signs are primarily used to indicate what?

Red regulatory signs are primarily used to indicate stop or prohibition. These signs are designed to convey important rules that must be followed to ensure road safety. For example, a red stop sign clearly instructs drivers to come to a complete stop at an intersection, while other red signs may indicate prohibition, such as "No Turn" or "Do Not Enter."

The use of red for these types of signs is standardized in traffic control measures because red is universally recognized as a color that indicates danger or the need for caution. This helps to ensure that drivers immediately recognize the importance of the message being conveyed. The clear and authoritative nature of red regulatory signs is critical for maintaining order and preventing accidents on the roadways.