Ключевые слова: black, brown, canal, civil, communication, concrete, conduit, connect, construction, danger, dig, dirt, distributive, earth, energy, equipment, excavation, frame, gray, ground, heat, industrial, industry, infrastructure, installation, joint, lay, line, network, new, outdoor, pipe, pipeline, plastic, power, protective, pvc, round, sewage, sewer, site, supply, technology, track, trench, tube, underground, valve, work,