aluminum
background
blue
car
drive
enter
entry
environment
forbidden
graphic
green
halt
hand
icon
illustration
isolated
keep
law
nature
no
not
oneway
pass
plate
prevent
prohibit
prohibition
protect
red
regulation
road
roadside
roadsign
round
rule
sign
signal
sky
stop
symbol
technology
traffic
transport
transportation
travel
tree
vehicle
warning
white