What sign advises drivers about an upcoming traffic control device?

The diamond-shaped sign is specifically used to indicate caution and alert drivers to potential hazards or changes in road conditions ahead. When it comes to advising drivers about an upcoming traffic control device, this shape is particularly significant because it signals the need for increased awareness and attention. These signs often warn about conditions like intersections, pedestrian crossings, or changes in roadway structure, which are crucial for safely navigating approaching traffic control devices like stop signs or signals.

This shape is standardized in traffic signage to ensure that drivers can quickly and easily recognize the sign's purpose, allowing for timely decision-making to adjust their driving accordingly.