Why are regulatory signs typically shown as red circles?

Regulatory signs are shown as red circles primarily to indicate mandatory actions that drivers and road users must follow. The use of red in these signs serves to attract attention and conveys a sense of seriousness or urgency about compliance. Regulatory signs often include important regulations such as speed limits, no entry, and prohibited actions, clearly signaling to drivers their obligations on the road.

The red circle format is standardized internationally, making it easier for drivers to understand the rules regardless of language, thereby enhancing road safety. Additionally, the visual prominence of a red circle helps in distinguishing these signs from warning signs and informational signs, which have different color coding and shapes. This clarity is essential for maintaining order and safety on the roads.