The New York Rapid-transit Subway

30 PARSONS ON NEW YORK RAPID-TRANSIT SUBWAY. [Minutes of the stations in large part by natural light, by making the overhead pavement of glass, known as “ vault-lights.” After experimenting with two kinds of vault-lights, it was decided to use glass set in reinforced concrete. The main beams of the station-roofs were set at 5-foot intervals; at right angles to them were placed secondary beams of either small steel I section or reinforced concrete, with a 1-inch twisted steel rod on the tension side. These smaller beams were set at intervals of about 5 feet, and between them was laid a sheet of reinforced concrete 2 inches in depth, with circular glass lights 23 inches in diameter, set at about 4 inches between centres. The reinforcement consisted of 1-inch twisted steel rods placed transversely, one between each row of vault-lights. In the event of any light being broken it is quite feasible to cut out. the light and re-set it without damage to the frame. The floors of the stations are of concrete with a granolithic surface, consisting of 1 part Portland cement and 2 parts sand, trowelled smooth. The stairways were first planned to be built in the ordinary manner with metal carriages and supports. Before construction was begun, however, the application of reinforced concrete had been adopted, and practically all the staircases have been built in this material. The steps are supported at intermediate points on columns 6 inches by 8 inches in exterior section and reinforced with -inch square bars tied together with {--inch loops at 12-inch intervals. The steps have a minimum thickness of 5 inches measured at the intersection of the rise and the tread, and these are also reinforced with 3-inch bars set 6 inches apart. The open sides of the stairs are protected by a plain wrought-iron grill, the main vertical bars of which are 12-inch pipe, with intermediate members 4 inch round, set about 5 inches between centres. As the ordinary sewer is about 13 feet below the surface of the street, and as the floors of the stations were usually below the sewers, it was impossible, except in a few cases, to get natural drainage to the sewers. Where natural drainage could not be secured, the stations were equipped with Shone ejectors, by which the water from, the lavatories and platform-washing was lifted into the sewers outside. Junctions. There are three important junctions on the railway. The first is at Bowling Green where the line from Brooklyn joins the line on Manhattan Island, the terminus of the latter being one station