Ключевые слова: asphalt, cement, city, cold, concentration, concrete, construction, cover, design, dirt, drain, drainage, environment, flowing, grate, grid, gutter, heavy, hole, industrial, infrastructure, iron, line, maintenance, manhole, marking, natural, old, pattern, perspective, plant, rain, repair, road, safety, sewage, sewer, sidewalk, steel, storm, street, surface, urban, waste, water,