angle
attention
background
blue
caution
center
clouds
color
communication
concepts
control
danger
direction
forbidden
highway
image
information
isolated
law
low
message
metal
nobody
object
octagon
outdoors
red
road
roadside
roadsign
safety
shape
sign
signal
sky
speed
stop
street
sunlight
symbol
text
traffic
transport
transportation
travel
vertical
view
warning
white
word