sign colors and shapes
regulation
black/white
motorist services guidance
blue
public recreation and scenic guidance
brown
exclusively to warn of existing or possible hazards on roadways or adjacent areas
diamond
exclusively for yield signs
equilateral triangle
indicated movements permitted, direction guidance
green
generally for guide signs
horizontal rectangle
exclusively for stop signs
octogon
construction and maintenance warning
orange
advance warning of no passing zones
pennant
school advance and school crossing signs
pentagon
stop or prohibition
red
railroad advance warning signals
round
generally for regulatory signs
vertical rectangle
general warning
yellow