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abstract
ahead
air
alert
area
attention
auto
background
black
blue
bright
car
caution
closeup
clouds
cloudscape
construction
danger
dig
driving
dusty
figure
grunge
metal
notice
obstacle
obstruction
orange
outdoors
progress
red
restoration
road
roadworks
safe
safety
sign
signage
signal
site
sky
speed
speed limit
stop
street
symbol
temporary
traffic
triangle
wait
warning
way
white
work
worker
yellow
zone