the shape of a warning sign is a/an _______________.
Standard Sign Shapes. Signs convey information to travelers not only by their messages and color, but through their shape as well. Special shapes are specifically assigned to certain types of signs so that travelers can recognize them quickly and react appropriately. In general, the greater number of sides on a sign, the more critical a message it conveys. This is why a circular shape was adopted for the Railroad Advance warning sign (i.e. infinite number of sides), as a collision between a train and a typical vehicle will nearly always end badly.