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above the subgrade of the tunnel. Three rows of piles were next driven on each side of the trench from
the west bank to the middle of the river and on them working platforms were built, forming two wharves
38 feet apart in the clear. Piles w : ere then driven over the area to be covered by the subway, 6 feet 4 inches
apart laterally and 8 teet longitudinally. They were cut oft about I I feet above the center line of each tube
and capped with timbers 12 inches square. A thoroughly-trussed framework was then floated over the piles
and sunk on them. The trusses were spaced so as to come between each transverse row of piles and were
connected by eight longitudinal sticks or stringers, two at the top and two at the bottom on each side. The
four at each side were just far enough apart to allow a special tongue and grooved 12-inch sheet piling to be
driven between them. This sheathing was driven to a depth of 10 to 15 feet below the bottom of the
finished tunnel.

A well-calked roof of three courses of i 2-inch timbers, separated by 2-inch plank, was then floated
over the piles and sunk. It had three timber shafts 7x17 teet in plan, and when it was in place and
covered with earth it formed the top of a caisson with the sheet piling on the sides and ends, the hitter being
driven after the roof was in place. The excavation below this caisson was made under air pressure, part of
the material being blown out by water jets and the remainder removed through the airlocks in the shafts.
When the excavation was completed, the piles were temporarily braced and the concrete and cast-iron lining
put in place, the piles being cut ofFas the concrete bed was laid up to them.

The second or eastern section of this crossing w : as earned on by a modification of the plan just men-
tioned. Instead of using a temporary timber roof on the side walls, the permanent iron and concrete upper
halt of the tunnels was employed as a roof for the caisson. The trench was dredged nearly to sub-grade
and its sides provided with wharves as before, running out to the completed halt ot the work. The
permanent foundation piles were then driven and a timber frame sunk over them to serve as a tjuide tor the
12-inch sheet piling around the site. Steel pilot piles with water jets were driven in advance of the wood-
sheet piles, and it they struck any boulders the latter were drilled and blasted. The steel piles were with-
drawn by a six-part tackle and hoisting engine, and then the wooden piles driven in their place.

When the piling was finished, a pontoon 35 feet wide, 106 feet long, and i 2 feet deep was built between
the wharves, and upon a separate platform or deck on it the upper half of the cast-iron shells were assembled,
their ends closed by steel-plate diaphragms and the whole covered with concrete. The pontoon was then sub-
merged several feet, parted at its center, and each half drawn out endwise from beneath the floating top of
the tunnel. The latter was then loaded and carefully sunk into place, the connection with the shore section



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being made by a diver, who entered the roof through a special opening. When it was finally in place, men
entered through the shore section and cut away the wood bottom, thus completing the caisson so that work
could proceed below it as before. Three of these caissons were required to complete the east end of the
crossing.

The construction of the approaches to the tunnel was carried out between heavy sheet piling. The
excavation was over 40 feet deep in places and very wet, and the success of the work was largely due to the
care taken in driving the I 2-inch sheet piling.

A number of interesting features should be noted in the methods of construction adopted on the Methods of
Brooklyn Extension. Construction

The types of construction on the Brooklyn Extension have already been spoken of. They are (i)
typical flat-roof steel beam subway from the Post-office, Manhattan, to Bowling Green; (2) reinforced
concrete typical subway in Battery Park, Manhattan, and from Clinton Street to the terminus, in Brooklyn;
(3) two single track cast-iron-lined tubular tunnels from Battery Park, under the East River, and under
Joralemon Street to Clinton Street, Brooklyn.



PAGE 66iNTERBOROUGH RAPID TRANSIT



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Under Broadway, Manhattan, the work is through sand, the vehicular and electric street car traffic, the
network of subsurface structures, and the high buildings making this one of the most difficult portions of the
road to build. The street traffic is so great that it was decided that during the daytime the surface of the
street should be maintained in a condition suitable for ordinary traffic. This was accomplished by making
openings in the sidewalk near the curb, at two points, and erecting temporary working platforms over the
street 16 feet from the surface. The excavations are made by the ordinary drift and tunnel method. The
excavated material is hoisted from the openings to the platforms and passed through chutes to wagons. On
the street surface, over and in advance of the excavations, temporary plank decks are placed and maintained
during the drifting and tunneling operations, and after the permanent subway structure has been erected up
to the time when the street surface is permanently restored. The roof of the subway is about 5 feet from the
surface of the street, which has made it necessary to care tor the gas and water mains. This has been done
by carrying the mains on temporary trestle structures over the sidewalks. The mains will be restored to
their former position when the subway structure is complete.

From Bowling Green, south along Broadsvay, State 'Street and in Battery Park, where the subway is of
reinforced concrete construction, the " open cut and cover " method is employed, the elevated and surface
railroad structures being temporarily supported by wooden and steel trusses and finally supported by perma-
nent foundations resting on the subway roof. From Battery Place, south along the loop work, the greater
portion of the excavation is made below mean high-water level, and necessitates the use of heavy tongue and
grooved sheeting and the operation of two centrifugal pumps, day and night.

The tubes under the East River, including the approaches, are each 6,544 feet in length. The tunnel
consists of two cast-iron tubes i 5 T _; feet diameter inside, the lining being constructed of cast-iron plates, cir-
cular in shape, bolted' together and reinforced by grouting outside of the plates and beton filling on the in-
side to the depth of the flanges. The tubes are being constructed under air pressure through solid rock
from the Manhattan side to the middle of the East River by the ordinary rock tunnel drift method, and on
the Brooklyn side through sand and silt by the use of hydraulic shields. Four shields have been installed,
weighing 51 tons each. They are driven by hydraulic pressure of about 2,000 tons. 1 he two shields drift-
ing to the center of the river from Garden Place are in water-bearing sand and are operated under air pres-
sure. The river tubes are on a }.i per cent, grade and in the center of the river will reach the deepest point,
about 94 feet below mean high-water level.

The typical subway of reinforced concrete from Clinton Street to the Flatbush Avenue terminus is being
constructed by the method commonly used on the Manhattan-Bronx route. From Borough Hall to the
terminus the route of the subway is directly below an elevated railway structure, which is temporarily supported
by timber bracing, having its bearing on the street surface and the tunnel timbers. The permanent support
will be masonry piers built upon the roof of the subway structure. Along this portion of the route are street
surface electric roads, but they are operated by overhead trolley and the tracks are laid on ordinary ties. It
has, therefore, been much less difficult to care for them during the construction of the subway. Work is
being prosecuted on the Brooklyn Extension day and night, and in Brooklyn the excavation is made much
more rapidly by employing the street surface trolley roads to remove the excavated material. Spur tracks
have been built and flat cars are used, much of the removal being done at night.



CHAPTER III
POWER HOUSE BUILDING

TH E power house is situated adjacent to the North River on the block hounded by West 5 Nth Street,
West 59th Street, Eleventh Avenue, and Twelfth Avenue. The plans were adopted after a
thorough study by the engineers of Interborough Rapid Transit Company of all the large power
houses already completed and of the designs of the large power houses in process of construction in America
and abroad. The building is large, and when fully equipped it will be capable of producing more power
than any electrical plant ever built, and the study of the designs of other power houses throughout the
world was pursued with the principal object of reducing to a minimum the possibility of interruption of
service in a plant producing the great power required.

The type of power house adopted provides for a single row of large engines and electric generators,
contained within an operating room placed beside a boiler house, with a capacity of producing, approximately,
not less than 100,000 horse power when the machinery is being operated at normal rating.

The work of preparing the detailed plans of the power house structure was, in the main, completed 1 ,0('iltio/l
early in 1902, and resulted in the present plan, which may briefly be described as follows: The structure is and Gcnct'ill
divided into two main parts an operating room and a boiler house, with a partition wall between the two ] ) / i //i of
sections. The face of the structure on Eleventh Avenue is 200 feet wide, of which width the boiler house takes Po-K'C/'
83 feet and the operating section 1 1 7 feet. The operating room occupies the northerly side of the structure
and the boiler house the southerly side. The designers were enabled to employ a contour of roof and wall
section for the northerly side that was identical with the roof and wall contour of the southerly side, so that
the building, when viewed from either end, presents a symmetrical appearance with both sides of the building
alike in form and design. The operating room section is practically symmetrical in its structure, with respect
to its center; it consists of a central area, with a truss roof over same along with galleries at both sides.
The galleries along the northerly side are primarily for the electrical apparatus, while those along the
southerly side are given up chiefly to the steam-pipe equipment. The boiler room section is also practically
symmetrical with respect to its center.

A sectional scheme of the power house arrangement was determined on, by which the structure was to
consist of five generating sections, each similar to the others in all its mechanical details; but, at a later date,
a sixth section was added, with space on the lot for a seventh section. Each section embraces one chimney
along with the following generating equipment: twelve boilers, two engines, each direct connected to a
5,000 kilowatt alternator; two condensing equipments, two boiler-feed pumps, two smoke-flue systems, and
detail apparatus necessary to make each section complete in itself. . The only variation is the turbine plant
hereafter referred to. In addition to the space occupied by the sections, an area was set aside, at the Eleventh
Avenue end of the structure, for the passage of the railway spur from the New York Central tracks. The




CROSS SECTION OF POWER HOL'SE IN' PERSPECTIVE



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total length of the original five-section power house was 585 feet 9^ inches, but the additional section after-
wards added makes the over all length of the structure 693 feet 9^4 inches. In the fourth section it w^as
decided to omit a regular engine with its 5,000 kilowatt generator, and in its place substitute a 5,000 kilowatt
lighting and exciter outfit. Arrangements were made, however, so that this outfit can afterward be replaced
by a regular 5,000 kilowatt traction generator.

The plan of the power station included a method of supporting the chimneys on steel columns, instead
of erecting them through the building, which modification allowed for the disposal of boilers in spaces
which would otherwise be occupied by the chimney bases. By this arrangement it was possible to place all
the boilers on one floor level. The economizers were placed above the boilers, instead of behind them,
which made a material saving in the width of the boiler room. This saving permitted the setting aside ot
the aforementioned gallery at the side of the operating room, closed off from both boiler and engine rooms,
for the reception of the main-pipe systems and tor a pumping equipment below it.

The advantages of the plan can be enumerated briefly as follows : The main engines, combined with
their alternators, lie in a single row along the center line of the operating room with the steam or operating
end of each engine facing the boiler house and the opposite end toward the electrical switching and
controlling apparatus arranged along the outside wall. Within the area between the boiler house and
operating room there is placed, for each engine, its respective complement ot pumping apparatus, all
controlled by and under the operating jurisdiction of the engineer for that engine. Each engineer has thus
full control of the pumping machinery required for his unit. Symmetrically arranged with respect to the
center line of each engine are the six boilers in the boiler room, and the piping from these six boilers forms
a short connection between the nozzles on the boilers and the throttles on the engine. The arrangement of
piping is alike for each engine, which results in a piping system of maximum simplicity that can be
controlled, in the event of difficulty, with a degree of certainty not possible with a more complicated system.
The main parts of the steam-pipe system can be controlled from outside this area.

The single tier of boilers makes it possible to secure a high and well ventilated boiler room with
ventilation into a story constructed above it, aside from that afforded by the windows themselves. The
boiler room will therefore be cool in warm weather and light, and all difficulties from escaping steam will be
minimized. In this respect the boiler room will be superior to corresponding rooms in plants of older
construction, where they are low, dark, and often very hot during the summer season. The placing ot the
economizers, with their auxiliary smoke flue connections, in the economizer room, all symmetrically arranged
with respect to each chimney, removes from the boiler room an element of disturbance and makes it possible
to pass directly from the boiler house to the operating room at convenient points along the length of the
power house structure. The location of each chimney in the center of the boiler house between sets of six
boilers divides the coal bunker construction into separate pockets by which trouble from spontaneous
combustion can be localized, and, as described later, the divided coal bunkers can provide for the storage
of different grades of coal. The unit basis on which the economizer and flue system is constructed will
allow making repairs to any one section without shutting oft" the portions not connected directly to the
section needing repair.

The floor of the power house between the column bases is a continuous mass ot concrete nowhere less
than two feet thick. The massive concrete foundations for the reciprocating engines contain each 1,400 yards



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PAGE 72INTERBOROUGH RAPID TRANSIT



THE SUBWAY



of concrete above mean high water level, and in some cases have twice as much below that point. The
total amount of concrete in the foundations of the finished power house is about 80,000 yards.

Water for condensing purposes is drawn from the river and discharged into it through two monolithic
concrete tunnels parallel to the axis of the building. The intake conduit has an oval interior, iox8 J i feet
in size, and a rectangular exterior cross-section; the outflow tunnel has a horseshoe-shape cross-section and
is built on top of the intake tunnel. These tunnels were built throughout in open trench, which, at the
shore end, was excavated in solid rock. At the river end the excavation was, at some places, almost entirely
through the fill and mud and was made in a cofferdam composed chiefly of sheet piles. As it was impossible
to drive these piles across the old timber crib which formed the old dock front, the latter was cut through
by a pneumatic caisson of wooden-stave construction, which formed part of one side of the cofferdam. At
the river end of the cofferdam the rock was so deep that the concrete could not be carried down to its sur-
face, and the tunnel section was built on a foundation of piles driven to the rock and cut off by a steam saw
19*2 feet below mean hightide. This section of the tunnel was built in a 65 x 48-foot floating caisson 24
feet deep. The concrete was rammed in it around the moulds and the sides were braced as it sunk. After
the tunnel sections were completed, the caisson was sunk, by water ballast, to a bearing on the pile foundation.

Adjacent to the condensing water conduits is the 10 x if-foot rectangular concrete tunnel, through
which the underground coal conveyor is installed between the shore end of the pier and the power house.

Steel Jf^O/'k The steel structure of the power house is independent of the walls, the latter being self-supporting and

used as bearing walls only for a few of the beams in the first floor. Although structurally a single building,
in arrangement it is essentially two, lying side by side and separated by a brick division wall.

There are 58 transverse and 9 longitudinal rows of main columns, the longitudinal spacing being T 8 feet
and 36 feet for different rows, with special bracing in the boiler house to accommodate the arrangement of
boilers. The columns are mainly of box section, made up of rolled or built channels and cover plates. They
are supported by cast-iron bases, resting on the granite capstones of the concrete foundation piers.

Both the boiler house and the engine house have five tiers of floor framing below the flat portion of the
roof, the three upper tiers of the engine house forming galleries on each side ot the operating room, which is
clear for the full height of the building.

The boiler house floors are, in general, framed with transverse plate girders and longitudinal rolled
beams, arranged to suit the particular requirements of the imposed loads ot the boilers, economizers, coal,
etc., while the engine room floors and pipe and switchboard galleries are in general framed with longitudinal
plate girders and transverse beams.

There are seven coal bunkers in the boiler house, of which five are 77 feet and two 41 feet in length by
60 feet in width at the top, the combined maximum capacity being 18,000 tons. The bunkers are separated
from each other by the six chimneys spaced along the center line of the boiler house. The bottom ot the
bunkers are at the fifth floor, at an elevation of about 66 feet above the basement. The bunkers are con-
structed with double, transverse, plate girder frames at each line of columns, combined with struts and ties,
which balance the outward thrust of the coal against the sides. The frames form the outline of the bunkers
with slides sloping at 45 degrees, and carry longitudinal I-beams, between which are built concrete arches,
reinforced with expanded metal, the whole surface being filled with concrete over the tops of the beams and
given a two-inch granolithic finish.



11 T H. AVENUE



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PAGE 74INTERBOROUGH



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TRANSIT



THE SUBWAY



HoUSC
Superstructure



The six chimneys, spaced 108 feet apart, and occupying the space between the ends of the adjacent
coal bunkers, are supported on plate-girder platforms in the fifth floor, leaving the space below clear for a
symmetrical arrangement of the boilers and economizers from end to end of the building. The platforms
are framed of single-web girders 8 feet deep, thoroughly braced and carrying on their top flanges a grillage
of 2O-inch I-beam. A system of bracing for both the chimney platforms and coal bunkers is carried down to
the foundations in traverse planes about 30 feet apart.

The sixth tier of beams constitute a flat roof over a portion of the building at the center and sides.
In the engine room, at this level, which is 64 feet above the engine-room floor, are provided the two longi-
tudinal lines of crane runway girders upon which are operated the engine-room cranes. Runways for
lO-ton hand cranes are also provided for the full length of the boiler room, and for nearly the full length of
the north panel in the engine room.

Some ot the loads carried by the steel structure are as follows: In the engine house, operating on the
longitudinal runways as mentioned, are one 6o-ton and one 25-ton electric traveling crane of 75 feet span.
The imposed loads of the steam-pipe galleries on the south side and the switchboard galleries on the north
side are somewhat irregularly distributed, but are equivalent to uniform loads of 250 to 400 pounds per
square foot. In the boiler house the weight of coal carried is about 45 tons per longitudinal toot of the
building; the weight of the brick chimneys is 1,200 tons each; economizers, with brick setting, about 4'.,
tons per longitudinal foot; suspended weight ot the boilers 96 tons each, and the weight ot the boiler
setting, carried on the first floor framing, 1 60 tons each. The weight of structural steel used in the com-
pleted building is about 11,000 tons.

The design of the facework of the power house received the personal attention of the directors
f th e company, and its character and the class of materials to be employed were carefully considered.
The influence of the design on the future value of the property and the condition ot the environment in
general were studied, together with the factors relating to the future ownership of the plant by the city.
Several plans were taken up looking to the construction of a power house of massive and simple design, but
it was finally decided to adopt an ornate style of treatment by which the structure would be rendered
architecturally attractive and in harmony with the recent tendencies of municipal and city improvements
from an architectural standpoint. At the initial stage of the power house design Mr. Stanford White, of
the firm ot McKim, Mead & White, of New York, volunteered his services to the company as an adviser
on the matter ot the design of the facework, and, as his offer was accepted, his connection with the work has
resulted in the development of the present exterior design and the selection of the materials used.

The Eleventh Avenue facade is the most elaborately treated, but the scheme of the main facade is
carried along both the 5 8th and 9th Street fronts. The westerly end of the structure, facing the river, may
ultimately be removed in case the power house is extended to the Twelfth Avenue building line for the
reception of fourteen generating equipments; and for this reason this wall is designed plainly ot less costly
material.

The general style of the facework is what may be called French Renaissance, and the color scheme has,
therefore, been made rather light in character. The base of the exterior walls has been finished with cut
granite up to the water table, above which they have been laid up with a light colored buff pressed brick.
This brick has been enriched by the use of similarly colored terra-cotta, which appears in the pilasters, about



INTERBOROUGH RAPID TRANSIT PAGE 75



T H E S U B \V A Y



the windows, in the several entablatures, and in the cornice and parapet work. The Eleventh Avenue facade
is further enriched by marble medallions, framed with terra-cotta, and by a title panel directly over the front
of the structure.

The main entrance to the structure is situated at its northeast corner, and, as the railroad track passes
along just inside the building, the entrance proper is the doorway immediately beyond the track, and opens


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