cable
car
crossing
danger
electric
environment
equipment
gate
illuminated
industrial
industry
iron
lamp
light
line
metal
motion
move
nobody
outdoor
power
public
rail
railing
railroad
railway
red
regulations
road
safe
safety
security
semaphore
shiny
sign
signal
sky
station
steel
stop
symbol
track
traffic
train
transport
transportation
travel
vehicle
warning
way