caution
conceptual
concrete
electric
electrical
equipment
facilities
grass
industrial
industry
infrastructure
junction
lamp
light
line
metal
pole
post
rail
railing
railroad
railway
red
road
roadside
semaphore
shoulder sleeper
sidelines
sign
signal
station
steel
stop
stoplight
track
trackage
tracking
traffic
train
transport
transportation
travel
urban
wait
warning
wayside