Which traffic sign shape is typically used for regulatory signs?

The octagon is specifically used for stop signs, which are regulatory signs that instruct drivers to come to a complete stop at an intersection. These regulatory signs are critical for maintaining traffic flow and ensuring the safety of all road users. The distinct shape of the octagon is universally recognized and helps convey the stop command effectively, making it an essential design choice for this type of sign.

Other shapes like the triangle are associated with warnings, indicating caution or the need to yield, while rectangles are often used for guide signs that provide directions or information. The pentagon shape is designated for school zone signs, alerting drivers to the presence of children and the need for extra caution. Each shape has its specific connotation, which helps drivers quickly understand the message being conveyed without the need for excessive reading, further emphasizing the importance of the octagon in regulatory contexts.