hatch

steam

protection

water

manhole

street

hot

city

main

vapor

hole

smoke

urban

pressure

metal

technology

sewer

damage

emergency

forbidden

iron

central

inspection

chamber

heat

loss

energy

construction

circle

crime

stop

zone

tape

red

police

security

caution

warning

barricade

barrier

hazard

danger

safety

striped

restricted

sign

symbol

restriction

attention

protect

dangerous

secured

heating

conduit

pipeline

supply

line

industrial

pit

pipework

old

crash

well

shaft

system