sewer networks underground structures 12 sewerage 11 galleries (mining) 10 tunneling works 8 drfting 6 water mains 6 more ... water tubes 5 utility nets 4 waste water treatment plants 4 combined sewerage system 3 cable networks 3 urban waste water 3 repairs 3 defects 3 pipelines 3 concrete constructions 2 history 2 channels 2 communication networks 2 waste water 2 flow of fluids 2 tunnelling machines 2 reconstruction 2 simulation and modelling 2 site investigation 2 water supply engineering 2 maintenance 2 applications programs 1 automated management systems 1 less ...