abstract
accident
alert
area
attention
background
banner
barricade
barrier
beware
black
border
caution
construction
cordon
cross
danger
design
forbidden
grunge
hazard
icon
illustration
industrial
isolated
line
police
protection
restricted
ribbon
road
safety
scene
secure
security
sign
signal
site
stop
strip
stripe
symbol
tape
traffic
under
warning
work
yellow
zone