37 Installation services of sidewalk bridges, pipes scaffolding, shoring, swing and suspended scaffolding, construction elevators, heavy duty debris netting, material hoists; rental of sidewalk bridges, pipes scaffolding, shoring, swing and suspended scaffolding, construction elevators, heavy duty debris netting, material hoists; repair and maintenance of sidewalk bridges, pipes scaffolding, shoring, swing and suspended scaffolding, construction elevators, heavy duty debris netting, material hoists