broken
central heating
chasm
city
communications
construction
corrosion
damage
digging
dirt
energy
engineering
environment
equipment
ground
heat
hole
industrial
infrastructure
insulation
iron
main
maintenance
mess
metal
metallic
network
new
obsolete
old
one
pipe
pipeline
pipeline network
pipeline system
pipes
pit
protection
reconstruction
repair
replacement
replacing
rust
steam
supply
technology
thermal
trench
underground pipes
work