Of the forty-eight stations, thirty-three are underground, eleven are on the viaduct portions of the road, and three are partly on the surface and partly underground, and one is partly on the surface and partly on the viaduct.

[Sidenote: _s.p.a.ce Occupied_]

The underground stations are at the street intersections, and, except in a few instances, occupy s.p.a.ce under the cross streets. The station plans are necessarily varied to suit the conditions of the different locations, the most important factor in planning them having been the amount of available s.p.a.ce. The platforms are from 200 to 350 feet in length, and about 16 feet in width, narrowing at the ends, while the center s.p.a.ce is larger or smaller, according to local conditions. As a rule the body of the station extends back about 50 feet from the edge of the platform.

At all local stations (except at 110th Street and Lenox Avenue) the platforms are outside of the tracks. (Plan and photograph on pages 30 and 31.) At Lenox Avenue and 110th Street there is a single island platform for uptown and downtown pa.s.sengers.

[Ill.u.s.tration: 28TH STREET STATION]

[Sidenote: _Island Platforms_]

At express stations there are two island platforms between the express and local tracks, one for uptown and one for downtown traffic. In addition, there are the usual local platforms at Brooklyn Bridge, 14th Street (photograph on page 34) and 96th Street. At the remaining express stations, 42d Street and Madison Avenue and 72d Street, there are no local platforms outside of the tracks, local and through traffic using the island platforms.

The island platforms at Brooklyn Bridge, 14th Street, and 42d Street and Madison Avenue are reached by mezzanine footways from the local platforms, it having been impossible to place entrances in the streets immediately over the platforms. At 96th Street there is an underground pa.s.sage connecting the local and island platforms, and at 72d Street there are entrances to the island platforms directly from the street because there is a park area in the middle of the street. Local pa.s.sengers can transfer from express trains and express pa.s.sengers from local trains without payment of additional fare by stepping across the island platforms.

At 72d Street, at 103d Street, and at 116th Street and Broadway the station platforms are below the surface, but the ticket booths and toilet rooms are on the surface; this arrangement being possible also because of the park area available in the streets. At Manhattan Street the platforms are on the viaduct, but the ticket booths and toilet rooms are on the surface. The viaduct at this point is about 68 feet above the surface, and escalators are provided. At many of the stations entrances have been arranged from the adjacent buildings, in addition to the entrances originally planned from the street.

[Sidenote: Kiosks]

The entrances to the underground stations are enclosed at the street by kiosks of cast iron and wire gla.s.s (photograph on page 33), and vary in number from two to eight at a station. The stairways are of concrete, reinforced by twisted steel rods. At 168th Street, at 181st Street, and at Mott Avenue, where the platforms are from 90 to 100 feet below the surface, elevators are provided.

[Ill.u.s.tration: WEST SIDE OF 23D STREET STATION]

At twenty of the underground stations it has been possible to use vault lights to such an extent that very little artificial light is needed. (Photograph on page 35.) Such artificial light as is required is supplied by incandescent lamps sunk in the ceilings.

Provision has been made for using the track circuit for lighting in emergency if the regular lighting circuit should temporarily fail.

[Ill.u.s.tration: KIOSKS AT COLUMBUS CIRCLE]

The station floors are of concrete, marked off in squares. At the junction of the floors and side walls a cement sanitary cove is placed. The floors drain to catch-basins, and hose bibs are provided for washing the floors.

[Ill.u.s.tration: BROOKLYN BRIDGE STATION]

Two types of ceiling are used, one flat, which covers the steel and concrete of the roof, and the other arched between the roof beams and girders, the lower f.l.a.n.g.es of which are exposed. Both types have an air s.p.a.ce between ceiling and roof, which, together with the air s.p.a.ce behind the inner side walls, permits air to circulate and minimizes condensation on the surface of the ceiling and walls.

[Ill.u.s.tration: PLAQUE SHOWING BEAVER AT ASTOR PLACE STATION]

The ceilings are separated into panels by wide ornamental mouldings, and the panels are decorated with narrower mouldings and rosettes. The bases of the walls are buff Norman brick. Above this is gla.s.s tile or glazed tile, and above the tile is a faience or terra-cotta cornice.

Ceramic mosaic is used for decorative panels, friezes, pilasters, and name-tablets. A different decorative treatment is used at each station, including a distinctive color scheme. At some stations the number of the intersecting street or initial letter of the street name is shown on conspicuous plaques, at other stations the number or letter is in the panel. At some stations artistic emblems have been used in the scheme of decoration, as at Astor Place, the beaver (see photograph on this page); at Columbus Circle, the great navigator's Caravel; at 116th Street, the seal of Columbia University.

The walls above the cornice and the ceilings are finished in white Keene cement.

[Ill.u.s.tration: EXPRESS STATION AT 14TH STREET, SHOWING ISLAND AND MEZZANINE PLATFORMS AND STAIRS CONNECTING THEM]

[Ill.u.s.tration: WEST SIDE OF COLUMBUS CIRCLE STATION (60TH STREET)--ILLUMINATED BY DAYLIGHT COMING THROUGH VAULT LIGHTS]

[Ill.u.s.tration: CARAVEL AND WALL DECORATION]

The ticket booths are of oak with bronze window grills and fittings.

There are toilet rooms in every station, except at the City Hall loop.

Each toilet room has a free closet or closets, and a pay closet which is furnished with a basin, mirror, soap dish, and towel rack. The fixtures are porcelain, finished in dull nickel. The soil, vent and water pipes are run in wall s.p.a.ces, so as to be accessible. The rooms are ventilated through the hollow columns of the kiosks, and each is provided with an electric fan. They are heated by electric heaters.

The woodwork of the rooms is oak; the walls are red slate wainscot and Keene cement.

Pa.s.sengers may enter the body of the station without paying fare. The train platforms are separated from the body of the station by railings. At the more important stations, separate sets of entrances are provided for incoming and outgoing pa.s.sengers, the stairs at the back of the station being used for entrances and those nearer the track being used for exits.

[Ill.u.s.tration: CITY HALL STATION]

An example of the care used to obtain artistic effects can be seen at the City Hall station. The road at this point is through an arched tunnel. In order to secure consistency in treatment the roof of the station is continued by a larger arch of special design. (See photograph on this page.) At 168th Street, and at 181st Street, and at Mott Avenue stations, where the road is far beneath the surface, it has been possible to build ma.s.sive arches over the stations and tracks, with spans of 50 feet.

CHAPTER II

TYPES AND METHODS OF CONSTRUCTION

Five types of construction have been employed in building the road: (1) the typical subway near the surface with flat roof and "I" beams for the roof and sides, supported between tracks with steel bulb-angle columns used on about 10.6 miles or 52.2 per cent. of the road; (2) flat roof typical subway of reenforced concrete construction supported between the tracks by steel bulb-angle columns, used for a short distance on Lenox Avenue and on the Brooklyn portion of the Brooklyn Extension, also on the Battery Park loop; (3) concrete lined tunnel used on about 4.6 miles or 23 per cent. of the road, of which 4.2 per cent. was concrete lined open cut work, and the remainder was rock tunnel work; (4) elevated road on steel viaduct used on about 5 miles or 24.6 per cent. of the road; (5) cast-iron tubes used under the Harlem and East Rivers.

[Sidenote: _Typical Subway_]

The general character of the flat roof "I" beam construction is shown in photograph on page 28 and drawing on this page. The bottom is of concrete. The side walls have "I" beam columns five feet apart, between which are vertical concrete arches, the steel acting as a support for the masonry and allowing the thickness of the walls to be materially reduced from that necessary were nothing but concrete used.

The tops of the wall columns are connected by roof beams which are supported by rows of steel columns between the tracks, built on concrete and cut stone bases forming part of the floor system.

Concrete arches between the roof beams complete the top of the subway.

Such a structure is not impervious, and hence, there has been laid behind the side walls, under the floor and over the roof a course of two to eight thicknesses of felt, each washed with hot asphalt as laid. In addition to this precaution against dampness, in three sections of the subway (viz.: on Elm Street between Pearl and Grand Streets, and on the approaches to the Harlem River tunnel, and on the Battery Park Loop) the felt waterproofing has been made more effective by one or two courses of hard-burned brick laid in hot asphalt, after the manner sometimes employed in constructing the linings of reservoirs of waterworks.

[Ill.u.s.tration: TYPICAL SECTION OF FOUR TRACK SUBWAY]

[Ill.u.s.tration: FOUR-TRACK SUBWAY--SHOWING CROSS-OVER SOUTH OF 18TH STREET STATION]

In front of the waterproofing, immediately behind the steel columns, are the systems of terra-cotta ducts in which the electric cables are placed. The cables can be reached by means of manholes every 200 to 450 feet, which open into the subway and also into the street. The number of these ducts ranges from 128 down to 32, and they are connected with the main power station at 58th and 59th Streets and the Hudson River by a 128-duct subway under the former street.

[Sidenote: _Reinforced Concrete Construction_]

The reinforced concrete construction subst.i.tutes for the steel roof beams, steel rods, approximating 1-1/4 inches square, laid in varying distances according to the different roof loads, from six to ten inches apart. Rods 1-1/8 inches in diameter tie the side walls, pa.s.sing through angle columns in the walls and the bulb-angle columns in the center. Layers of concrete are 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 are used and angle columns five feet apart. The concrete of the side walls is from fifteen to eighteen inches thick. This type is shown by photographs on page 41. The rods used are of both square and twisted form.

[Ill.u.s.tration: LAYING SHEET WATERPROOFING IN BOTTOM]

[Ill.u.s.tration: SPECIAL BRICK AND ASPHALT WATERPROOFING]

[Sidenote: _Methods of Construction Typical Subway_]

The construction of the typical subway has been carried on by a great variety of methods, partly adopted on account of the conditions under which the work had to be prosecuted and partly due to the personal views of the different sub-contractors. The work was all done by open excavation, the so-called "cut and cover" system, but the conditions varied widely along different parts of the line, and different means were adopted to overcome local difficulties. The distance of the rock surface below the street level had a marked influence on the manner in which the excavation of the open trenches could be made. In some places this rock rose nearly to the pavement, as between 14th and 18th Streets. At other places the subway is located in water-bearing loam and sand, as in the stretch between Pearl and Grand Streets, where it was necessary to employ a special design for the bottom, which is ill.u.s.trated by drawing on page 42.

This part of the route includes the former site of the ancient Collect Pond, familiar in the early history of New York, and the excavation was through made ground, the pond having been filled in for building purposes after it was abandoned for supplying water to the city. The excavations through Ca.n.a.l Street, adjacent, were also through made ground, that street having been at one time, as its name implies, a ca.n.a.l.

From the City Hall to 9th Street was sand, presenting no particular difficulties except through the territory just described.

At Union Square rock was encountered on the west side of Fourth Avenue from the surface down. On the east side of the street, however, at the surface was sand, which extended 15 feet down to a sloping rock surface. The tendency of the sand to a slide off into the rock excavation required great care. The work was done, however, without interference with the street traffic, which is particularly heavy at that point.