Anonymous - The New York Subway
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Anonymous >> The New York Subway
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Ordinarily, the arrangement of overlap sections increases the length
of block sections by the length of the overlap, and as the length of
the section fixed the minimum spacing of trains, it was imperative to
make the blocks as short as consistent with safety, in order not to
cut down the carrying capacity of the railway. This led to a study of
the special problem presented by subway signaling and a development of
a blocking system upon lines which it is believed are distinctly in
advance of anything heretofore done in this direction.
[Illustration: REAR VIEW OF BLOCK SIGNAL POST, SHOWING TRANSFORMER AND
INSTRUMENT CASES WITH DOORS OPEN]
Block section lengths are governed by speed and interval between
trains. Overlap lengths are determined by the distance in which a
train can be stopped at a maximum speed. Usually the block section
length is the distance between signals, plus the overlap; but where
maximum traffic capacity is desired the block section length can be
reduced to the length of two overlaps, and this was the system adopted
for the Interborough. The three systems of blocking trains, with and
without overlaps, is shown diagramatically on page 143, where two
successive trains are shown at the minimum distances apart for
"clear" running for an assumed stopping distance of 800 feet. The
system adopted for the subway is shown in line "C," giving the least
headway of the three methods.
[Illustration: PNEUMATIC TRACK STOP, SHOWING STOP TRIGGER IN UPRIGHT
POSITION]
The length of the overlap was given very careful consideration by the
Interborough Rapid Transit Company, who instituted a series of tests
of braking power of trains; from these and others made by the
Pennsylvania Railroad Company, curves were computed so as to determine
the distance in which trains could be stopped at various rates of
speed on a level track, with corrections for rising and falling to
grades up to 2 per cent. Speed curves were then plotted for the trains
on the entire line, showing at each point the maximum possible speed,
with the gear ratio of the motors adopted. A joint consideration of
the speeds, braking efforts, and profile of the road were then used to
determine at each and every point on the line the minimum allowable
distance between trains, so that the train in the rear could be
stopped by the automatic application of the brakes before reaching a
train which might be standing at a signal in advance; in other words,
the length of the overlap section was determined by the local
conditions at each point.
In order to provide for adverse conditions the actual braking
distances was increased by 50 per cent.; for example, the braking
distance of a train moving 35 miles an hour is 465 feet, this would be
increased 50 per cent. and the overlap made not less than 697 feet.
With this length of overlap the home signals could be located 697 feet
apart, and the block section length would be double this or 1394 feet.
The average length of overlaps, as laid out, is about 800 feet, and
the length of block sections double this, or 1,600 feet.
[Illustration: VIEW UNDER CAR, SHOWING TRIGGER ON TRUCK IN POSITION TO
ENGAGE WITH TRACK STOP]
The protection provided by this unique arrangement of signals is
illustrated on page 143. Three positions of train are shown:
"A." MINIMUM distance between trains: The first train has
just passed the home signal, the second train is stopped by
the home signal in the rear; if this train had failed to stop
at this point, the automatic stop would have applied the air
brake and the train would have had the overlap distance in
which to stop before it could reach the rear of the train in
advance; therefore, under the worst conditions, no train can
get closer to the train in advance than the length of the
overlap, and this is always a safe stopping distance.
"B." CAUTION distance between train: The first train in same
position as in "A," the second train at the third home signal
in the rear; this signal can be passed under caution, and
this distance between trains is the caution distance, and is
always equal to the length of the block section, or two
overlaps.
"C." CLEAR distance between trains: First train in same
position as in "A," second train at the fourth home signal in
the rear; at this point both the home and distant signals are
clear, and the distance between the trains is now the clear
running distance; that is, when the trains are one block
section plus an overlap apart they can move under clear
signal, and this distance is used in determining the running
schedule. It will be noted in "C" that the first train has
the following protection: Home signals 1 and 2 in stop
position, together with the automatic stop at signal 2 in
position to stop a train, distant signal 1, 2, and 3 all at
caution, or, in other words, a train that has stopped is
always protected by two home signals in its rear, and by
three caution signals, in addition to this an automatic stop
placed at a safe stopping distance in the rear of the train.
[Illustration: ELECTRO-PNEUMATIC INTERLOCKING MACHINE ON STATION
PLATFORM]
[Illustration: SPECIAL INTERLOCKING SIGNAL CABIN SOUTH OF BROOKLYN
BRIDGE STATION]
[Sidenote: _Description
of Block
Signaling
System_]
The block signaling system as installed consists of automatic
overlapping system above described applied to the two express tracks
between City Hall and 96th Street, a distance of six and one-half
miles, or thirteen miles of track; and to the third track between 96th
and 145th Streets on the West Side branch, a distance of two and
one-half miles. This third track is placed between the two local
tracks, and will be used for express traffic in both directions,
trains moving toward the City Hall in the morning and in the opposite
direction at night; also the two tracks from 145th Street to Dyckman
Street, a distance of two and one-half miles, or five miles of track.
The total length of track protected by signals is twenty-four and
one-half miles.
The small amount of available space in the subway made it necessary to
design a special form of the signal itself. Clearances would not
permit of a "position" signal indication, and, further, a position
signal purely was not suitable for the lighting conditions of the
subway. A color signal was therefore adopted conforming to the adopted
rules of the American Railway Association. It consists of an iron case
fitted with two white lenses, the upper being the home signal and the
lower the distant. Suitable colored glasses are mounted in slides
which are operated by pneumatic cylinders placed in the base of the
case. Home and dwarf signals show a red light for the danger or "stop"
indication. Distant signals show a yellow light for the "caution"
indication. All signals show a green light for the "proceed" or clear
position. Signals in the subway are constantly lighted by two
electric lights placed back of each white lens, so that the lighting
will be at all times reliable.
On the elevated structure, semaphore signals of the usual type are
used. The signal lighting is supplied by a special alternating current
circuit independent of the power and general lighting circuits.
A train stop or automatic stop of the Kinsman system is used at all
block signals, and at many interlocking signals. This is a device for
automatically applying the air brakes to the train if it should pass a
signal in the stop position. This is an additional safeguard only to
be brought into action when the danger indication has for any reason
been disregarded, and insures the maintenance of the minimum distance
between trains as provided by the overlaps established.
Great care has been given to the design, construction, and
installation of the signal apparatus, so as to insure reliability of
operation under the most adverse conditions, and to provide for
accessibility to all the parts for convenience in maintenance. The
system for furnishing power to operate and control the signals
consists of the following:
Two 500-volt alternating current feed mains run the entire length of
the signal system. These mains are fed by seven direct-current
motor-driven generators operated in multiple located in the various
sub-power stations. Any four of these machines are sufficient to
supply the necessary current for operating the system. Across these
alternating mains are connected the primary coils of track
transformers located at each signal, the secondaries of which supply
current of about 10 volts to the rails of the track sections. Across
the rails at the opposite end of the section is connected the track
relay, the moving element of which operates a contact. This contact
controls a local direct-current circuit operating, by compressed air,
the signal and automatic train stop.
Direct current is furnished by two mains extending the length of the
system, which are fed by eight sets of 16-volt storage batteries in
duplicate. These batteries are located in the subway at the various
interlocking towers, and are charged by motor generators, one of which
is placed at each set of batteries. These motor generators are driven
by direct current from the third rail and deliver direct current of 25
volts.
The compressed air is supplied by six air compressors, one located at
each of the following sub-stations: Nos. 11, 12, 13, 14, 16, and 17.
Three of these are reserve compressors. They are motor-driven by
direct-current motors, taking current from the direct-current buss
bars at sub-stations at from 400 to 700 volts. The capacity of each
compressor is 230 cubic feet.
[Illustration: MAIN LINE, PIPING AND WIRING FOR BLOCK AND INTERLOCKING
SYSTEM, SHOWING JUNCTION BOX ON COLUMN]
The motor-driven air compressors are controlled by a governor which
responds to a variation of air pressure of five pounds or less. When
the pressure has reached a predetermined point the machine is stopped
and the supply of cooling water shut off. When the pressure has fallen
a given amount, the machine is started light, and when at full speed
the load is thrown on and the cooling water circulation reestablished.
Oiling of cylinders and bearings is automatic, being supplied only
while the machines are running.
Two novel safety devices having to do especially with the signaling
may be here described. The first is an emergency train stop. It is
designed to place in the hands of station attendants, or others, the
emergency control of signals. The protection afforded is similar in
principle to the emergency brake handle found in all passenger cars,
but operates to warn all trains of an extraneous danger condition. It
has been shown in electric railroading that an accident to apparatus,
perhaps of slight moment, may cause an unreasoning panic, on account
of which passengers may wander on adjoining tracks in face of
approaching trains. To provide as perfectly as practicable for such
conditions, it has been arranged to loop the control of signals into
an emergency box set in a conspicuous position in each station
platform. The pushing of a button on this box, similar to that of the
fire-alarm signal, will set all signals immediately adjacent to
stations in the face of trains approaching, so that all traffic may be
stopped until the danger condition is removed.
The second safety appliance is the "section break" protection. This
consists of a special emergency signal placed in advance of each
separate section of the third rail; that is, at points where trains
move from a section fed by one sub-station to that fed by another.
Under such conditions the contact shoes of the train temporarily span
the break in the third rail. In case of a serious overload or ground
on one section, the train-wiring would momentarily act as a feeder for
the section, and thus possibly blow the train fuses and cause delay.
In order, therefore, to prevent trains passing into a dangerously
overloaded section, an overload relay has been installed at each
section break to set a "stop" signal in the face of an approaching
train, which holds the train until the abnormal condition is removed.
[Illustration: THREE METHODS OF BLOCK SIGNALING]
[Illustration: DIAGRAM OF OVERLAPPING BLOCK SIGNAL SYSTEM
ILLUSTRATING POSSIBLE POSITIONS OF TRAINS RUNNING UNDER SAME]
[Sidenote: _Interlocking
System_]
The to-and-fro movement of a dense traffic on a four-track railway
requires a large amount of switching, especially when each movement is
complicated by junctions of two or more lines. Practically every
problem of trunk line train movement, including two, three, and
four-track operation, had to be provided for in the switching plants
of the subway. Further, the problem was complicated by the restricted
clearances and vision attendant upon tunnel construction. It was
estimated that the utmost flexibility of operation should be provided
for, and also that every movement be certain, quick, and safe.
All of the above, which are referred to in the briefest terms only,
demanded that all switching movements should be made through the
medium of power-operated interlocking plants. These plants in the
subway portions of the line are in all cases electro-pneumatic, while
in the elevated portions of the line mechanical interlocking has been,
in some cases, provided.
A list of the separate plants installed will be interesting, and is
given below:
Location. Interlocking Working
Machines. Levers.
MAIN LINE.
City Hall, 3 32
Spring Street, 2 10
14th Street, 2 16
18th Street, 1 4
42d Street, 2 15
72d Street 2 15
96th Street 2 19
WEST SIDE BRANCH.
100th Street, 1 6
103d Street, 1 6
110th Street, 2 12
116th Street, 2 12
Manhattan Viaduct, 1 12
137th Street, 2 17
145th Street, 2 19
Dyckman Street, 1 12
216th Street, 1 14
EAST SIDE BRANCH.
135th Street, 2 6
Lenox Junction, 1 7
145th Street, 1 9
Lenox Avenue Yard, 1 35
Third and Westchester Avenue Junction, 1 13
St. Anna Avenue, 1 24
Freeman Street, 1 12
176th Street, 2 66
---- ----
Total, 37 393
The total number of signals, both block and interlocking, is as follows:
Home signals, 354
Dwarf signals, 150
Distant signals, 187
----
Total, 691
Total number of switches, 224
It will be noted that in the case of the City Hall Station three
separate plants are required, all of considerable size, and intended
for constant use for a multiplicity of movements. It is, perhaps,
unnecessary to state that all the mechanism of these important
interlocking plants is of the most substantial character and provided
with all the necessary safety appliances and means for rapidly setting
up the various combinations. The interlocking machines are housed in
steel concrete "towers," so that the operators may be properly
protected and isolated in the performance of their duties.
CHAPTER X
SUBWAY DRAINAGE
The employment of water-proofing to the exterior surfaces of the
masonry shell of the tunnel, which is applied to the masonry, almost
without a break along the entire subway construction, has made it
unnecessary to provide an extensive system of drains, or sump pits, of
any magnitude, for the collection and removal of water from the
interior of the tunnel.
On the other hand, however, at each depression or point where water
could collect from any cause, such as by leakage through a cable
manhole cover or by the breaking of an adjacent water pipe, or the
like, a sump pit or drain has been provided for carrying the water
away from the interior of the tunnel.
For all locations, where such drains, or sump pits, are located above
the line of the adjacent sewer, the carrying of the water away has
been easy to accomplish by employing a drain pipe in connection with
suitable traps and valves.
In other cases, however, where it is necessary to elevate the water,
the problem has been of a different character. In such cases, where
possible, at each depression where water is liable to collect, a well,
or sump pit, has been constructed just outside the shell of the
tunnel. The bottom of the well has been placed lower than the floor of
the tunnel, so that the water can flow into the well through a drain
connecting to the tunnel.
Each well is then provided with a pumping outfit; but in the case of
these wells and in other locations where it is necessary to maintain
pumping devices, it has not been possible to employ a uniform design
of pumping equipment, as the various locations offer different
conditions, each employing apparatus best suited to the requirements.
In no case, except two, is an electric pump employed, as the
employment of compressed air was considered more reliable.
The several depressions at which it is necessary to maintain a pumping
plant are enumerated as follows:
No. 1--Sump at the lowest point on City Hall Loop.
No. 2--Sump at intersection of Elm and White Streets.
No. 3--Sump at 38th Street in the Murray Hill Tunnel.
No. 4--Sump at intersection of 46th Street and Broadway.
No. 5--Sump at intersection of 116th Street and Lenox Avenue.
No. 6--Sump at intersection of 142d Street and Lenox Avenue.
No. 7--Sump at intersection of 147th Street and Lenox Avenue.
No. 8--Sump at about 144th Street in Harlem River approach.
No. 9--Sump at the center of the Harlem River Tunnel.
No. 10--Sump at intersection of Gerard Avenue and 149th Street.
In addition to the above mentioned sumps, where pumping plants are
maintained, it is necessary to maintain pumping plants at the
following points:
Location No. 1--At the cable tunnel constructed under the
Subway at 23d Street and Fourth Avenue.
Location No. 2--At the sub-subway at 42d Street and Broadway.
Location No. 3--At the portal of the Lenox Avenue extension
at 148th Street.
Location No. 4--At the southerly end of the Harlem River tube.
Location No. 5--At the northerly end of the Harlem River tube.
Location No. 6--At the portal at Bergen Avenue and 149th Street.
In the case of the No. 1 sump a direct-connected electric
triple-plunger pump is employed, situated in a pump room about 40 feet
distant from the sump pit. In the case of Nos. 2, 4, and 7 sumps,
automatic air lifts are employed. This apparatus is placed in those
sump wells which are not easily accessible, and the air lift was
selected for the reason that no moving parts are conveyed in the
air-lift construction other than the movable ball float and valve
which control the device. The air lift consists of concentric piping
extending several feet into the ground below the bottom of the well,
and the water is elevated by the air producing a rising column of
water of less specific weight than the descending column of water
which is in the pipe extending below the bottom of the sump well.
In the case of Nos. 3 and 5 sumps, and for Location No. 1, automatic
air-operated ejectors have been employed, for the reason that the
conditions did not warrant the employment of air lifts or electric or
air-operated pumps.
In the case of Nos. 6, 8, 9, and 10 sumps and for Locations Nos. 2, 4,
and 5, air-operated reciprocating pumps will be employed. These pumps
will be placed in readily accessible locations, where air lifts could
not be used, and this type of pump was selected as being the most
reliable device to employ.
In the case of Location No. 3, where provision has to be made to
prevent a large amount of yard drainage, during a storm, from entering
the tunnel where it descends from the portal, it was considered best
to employ large submerged centrifugal pumps, operated by reciprocating
air engines. Also for the portal, at Location No. 6, similar
centrifugal pumps will be employed, but as compressed air is not
available at this point, these pumps will be operated by electric
motors.
The air supply to the air-operating pumping devices will be
independent from the compressed air line which supplies air to the
switch and signal system, but break-down connections will be made
between the two systems, so that either system can help the other out
in case of emergency.
A special air-compressor plant is located at the 148th Street repair
shop, and another plant within the subway at 41st Street, for
supplying air to the pumps, within the immediate locality of each
compressor plant. For the more remote pumps, air will be supplied by
smaller air compressors located within passenger stations. In one
case, for the No. 2 sump, air will be taken from the switch and signal
air-compressor plant located at the No. 11 sub-station.
CHAPTER XI
REPAIR AND INSPECTION SHED
While popularly and not inaccurately known as the "Subway System," the
lines of the Interborough Company comprise also a large amount of
trackage in the open air, and hence the rolling stock which has
already been described is devised with the view to satisfying all the
peculiar and special conditions thus involved. A necessary corollary
is the requirement of adequate inspection and repair shops, so that
all the rolling stock may at all times be in the highest state of
efficiency; and in this respect the provision made by the company has
been lavish and liberal to a degree.
The repair and inspection shop of the Interborough Rapid Transit
Company adjoins the car yards of the company and occupies the entire
block between Seventh Avenue on the west, Lenox Avenue and the Harlem
River on the east, 148th Street on the south, and 149th Street on the
north. The electric subway trains will enter the shops and car yard by
means of the Lenox Avenue extension, which runs directly north from
the junction at 142d Street and Lenox Avenue of the East Side main
line. The branch leaves the main line at 142d Street, gradually
approaches the surface, and emerges at about 147th Street.
[Sidenote: _General
Arrangement_]
The inspection shed is at the southern end of the property and
occupies an area of approximately 336 feet by 240 feet. It is divided
into three bays, of which the north bay is equipped with four tracks
running its entire length, and the middle bay with five tracks. The
south bay contains the machine-tool equipment, and consists of
eighteen electrically driven machines, locker and wash rooms, heating
boilers, etc., and has only one track extending through it.
[Sidenote: _Construction_]
The construction of the inspection shops is that which is ordinarily
known as "reinforced concrete," and no wood is employed in the walls
or roof. The building is a steel structure made up of four rows of
center columns, which consist of twenty-one bays of 16 feet each,
supporting the roof trusses. The foundations for these center columns
are concrete piers mounted on piles. After the erection of the steel
skeleton, the sides of the building and the interior walls are
constructed by the use of 3/4-inch furring channels, located 16 inches
apart, on which are fastened a series of expanded metal laths. The
concrete is then applied to these laths in six coats, three on each
side, and termed respectively the scratch coat, the rough coat, and
the fining coat. In the later, the concrete is made with white sand,
to give a finished appearance to the building.
The roof is composed of concrete slabs, reinforced with expanded metal
laths and finished with cement and mortar. It is then water-proofed
with vulcanite water-proofing and gravel.
In this connection it might be said that, although this system of
construction has been employed before, the building under
consideration is the largest example of this kind of work yet done in
the neighborhood of New York City. It was adopted instead of
corrugated iron, as it is much more substantial, and it was considered
preferable to brick, as the later would have required much more
extensive foundations.
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