accident
airport
alert
asphalt
attention
background
blank
boundary
caution
concrete
cone
control
danger
empty
equipment
flat
hazard
highway
icon
mark
marker
object
open
orange
plastic
pole
protection
red
reflective
repair
road
roadwork
safe
safety
security
sign
signal
space
spot
stop
striped
symbol
traffic
transportation
walk
warning
way
white
white space
work