bar bars building closeup construction hard iron metal scaffold scaffolding stack stacked staging steel stuts texture architecture building work construction work dust protection facade metal work pipes railing rails safety safety mesh steel scaffolding white mesh additions alterations angled angles building-construction building-site building-work construction-site construction-work danger development height high industrial metal-work patterned patterns reinforced reinforcing safe secure security steel-scaffolding tall work concrete project site structure tools worker buildings external heights lifts protected protection work-safe workmen construction helmet sacfety line safety harness safety helmet welder welders welding bridge constructions enginering flyover highway motorway road transport transportation underconstruction crane greyscale building construction construction sites cranes