New York Subway.
Part of the New York Subway is of reinforced concrete. Steel rods, about 11⁄4 inches square were laid at varying distances according to the different roof loads, from six to ten inches apart. Rods 11⁄8 inches in diameter tie the side walls, passing through angle columns in the walls and the bulb-angle columns in the centre. Layers of concrete were laid over the roof rods to a thickness of from eighteen to thirty inches, and carried two inches below the rods, imbedding them. For the sides similar square rods and concrete were used and angle columns five feet apart. The concrete of the side walls is from fifteen to eighteen inches thick.
River des Pêres Bridge, Forest Park, St. Louis.
Memorial Bridge, Washington, D. C.