The alternators for which the new Interborough Power House are designed will deliver to the bus bars 100,000 electrical horse power. The current delivered by these alternators reverses its direction fifty times per second and in connecting dynamos just coming into service with those already in operation the allowable difference in phase relation at the instant the circuit is completed is, of course, but a fraction of the fiftieth of a second. Where the power to be controlled is so great, the potential so high, and the speed requirements in respect to synchronous operation so exacting, it is obvious that the perfection of control attained in some of our modern plants is not their least characteristic.

[Sidenote: Switching Apparatus]

The switch used for the 11,000 volt circuits is so constructed that the circuits are made and broken under oil, the switch being electrically operated. Two complete and independent sets of bus bars are used, and the connections are such that each alternator and each feeder may be connected to either of these sets of bus bars at the will of the operator. From alternators to bus bars the current passes, first, through the alternator switch, and then alternatively through one or the other of two selector switches which are connected, respectively, to the two sets of bus bars.



Provision is made for an ultimate total of twelve sub-stations, to each of which as many as eight feeders may be installed if the development of the company's business should require that number. But eight sub-stations are required at present, and to some of these not more than three feeders each are necessary. The aggregate number of feeders installed for the initial operation of the subway system is thirty-four.

Each feeder circuit is provided with a type H-oil switch arranged to be open and closed at will by the operator, and also to open automatically in the case of abnormal flow of current through the feeder. The feeders are arranged in groups, each group being supplied from a set of auxiliary bus bars, which in turn receives its supply from one or the other of the two sets of main bus bars; means for selection being provided as in the case of the alternator circuits by a pair of selector switches, in this case designated as group switches. The diagram on page 93 illustrates the essential features of the organization and connections of the 11,000 volt circuits in the power house.



Any and every switch can be opened or closed at will by the operator standing at the control board described. The alternator switches are provided also with automatic overload and reversed current relays, and the feeder switches, as above mentioned, are provided with automatic overload relays. These overload relays have a time attachment which can be set to open the switch at the expiration of a predetermined time ranging from .3 of a second to 5 seconds.



The type H-oil switch is operated by an electric motor through the intervention of a mechanism comprising powerful springs which open and close the switch with great speed. This switch when opened introduces in each of the three sides of the circuit two breaks which are in series with each other. Each side of the circuit is separated from the others by its location in an enclosed compartment, the walls of which are brick and soapstone. The general construction of the switch is illustrated by the photograph on page 94.



Like all current-carrying parts of the switches, the bus bars are enclosed in separate compartments. These are constructed of brick, small doors for inspection and maintenance being provided opposite all points where the bus bars are supported upon insulators. The photographs on pages 95 and 96 are views of a part of the bus bar and switch compartments.



The oil switches and group bus bars are located upon the main floor and extend along the 59th Street wall of the engine room a distance of about 600 feet. The main bus bars are arranged in two lines of brick compartments, which are placed below the engine-room floor. These bus bars are arranged vertically and are placed directly beneath the rows of oil switches located upon the main floor of the power house. Above these rows of oil switches and the group bus bars, galleries are constructed which extend the entire length of the power house, and upon the first of these galleries at a point opposite the middle of the power house are located the control board and instrument board, by means of which the operator in charge regulates and directs the entire output of the plant, maintaining a supply of power at all times adequate to the demands of the transportation service.



[Sidenote: The Control Board]

The control board is shown in the photograph on page 97. Every alternator switch, every selector switch, every group switch, and every feeder switch upon the main floor is here represented by a small switch. The small switch is connected into a control circuit which receives its supply of energy at 110 volts from a small motor generator set and storage battery. The motors which actuate the large oil switches upon the main floor are driven by this 110 volt control current, and thus in the hands of the operator the control switches make or break the relatively feeble control currents, which, in turn, close or open the switches in the main power circuits. The control switches are systematically assembled upon the control bench board in conjunction with dummy bus bars and other apparent (but not real) metallic connections, the whole constituting at all times a correct diagram of the existing connections of the main power circuits. Every time the operator changes a connection by opening or closing one of the main switches, he necessarily changes his diagram so that it represents the new conditions established by opening or closing the main switch. In connection with each control switch two small bull's-eye lamps are used, one red, to indicate that the corresponding main switch is closed, the other green, to indicate that it is open. These lamps are lighted when the moving part of the main switch reaches approximately the end of its travel. If for any reason, therefore, the movement of the control switch should fail to actuate the main switch, the indicator lamp will not be lighted.



The control board is divided into two parts—one for the connections of the alternators to the bus bars and the other for the connection of feeders to bus bars. The drawing on page 97 shows in plain view the essential features of the control boards.

[Sidenote: The Instrument Board]

A front view of the Instrument Board is shown on page 97. This board contains all indicating instruments for alternators and feeders. It also carries standardizing instruments and a clock. In the illustration the alternator panels are shown at the left and the feeder panels at the right. For the alternator panels, instruments of the vertical edgewise type are used. Each vertical row comprises the measuring instruments for an alternator. Beginning at the top and enumerating them in order these instruments are: Three ammeters, one for each phase, a volumeter, an indicating wattmeter, a power factor indicator and a field ammeter. The round dial instrument shown at the bottom of each row of instruments is a three-phase recording wattmeter.

A panel located near the center of the board between alternator panels and feeder panels carries standard instruments used for convenient calibration of the alternator and feeder instruments. Provision is made on the back of the board for convenient connection of the standard instruments in series with the instruments to be compared. The panel which carries the standard instruments also carries ammeters used to measure current to auxiliary circuits in the power house.

For the feeder board, instruments of the round dial pattern are used, and for each feeder a single instrument is provided, viz., an ammeter. Each vertical row comprises the ammeters belonging to the feeders which supply a given sub-station, and from left to right these are in order sub-stations Nos. 11, 12, 13, 14, 15, 16, 17, and 18; blank spaces are left for four additional sub-stations. Each horizontal row comprises the ammeter belonging to feeders which are supplied through a given group switch.

This arrangement in vertical and horizontal lines, indicating respectively feeders to given sub-stations and feeders connected to the several group switches, is intended to facilitate the work of the operator. A glance down a vertical row without stopping to reach the scales of the instruments will tell him whether the feeders are dividing with approximate equality the load to a given sub-station. Feeders to different sub-stations usually carry different loads and, generally speaking, a glance along a horizontal row will convey no information of especial importance. If, however, for any reason the operator should desire to know the approximate aggregate load upon a group of feeders this systematic arrangement of the instruments is of use.



[Sidenote: Alternating Current Distribution to Sub-Stations Power House Ducts and Cables]

From alternators to alternator switches the 11,000 volt alternating currents are conveyed through single conductor cables, insulated by oil cambric, the thickness of the wall being 12/32 of an inch. These conductors are installed in vitrified clay ducts. From dynamo switches to bus bars and from bus bars to group and feeder switches, vulcanized rubber insulation containing 30 per cent. pure Para rubber is employed. The thickness of insulating wall is 9/32 of an inch and the conductors are supported upon porcelain insulators.

[Sidenote: Conduit System for Distribution]

From the power house to the subway at 58th Street and Broadway two lines of conduit, each comprising thirty-two ducts, have been constructed. These conduits are located on opposite sides of the street. The arrangement of ducts is 8 x 4, as shown in the section on page 96.



The location and arrangement of ducts along the line of the subway are illustrated in photographs on pages 98 and 99, which show respectively a section of ducts on one side of the subway, between passenger stations, and a section of ducts and one side of the subway, beneath the platform of a passenger station. From City Hall to 96th Street (except through the Park Avenue Tunnel) sixty-four ducts are provided on each side of the subway. North of 96th Street sixty-four ducts are provided for the West-side lines and an equal number for the East-side lines. Between passenger stations these ducts help to form the side walls of the subway, and are arranged thirty-two ducts high and two ducts wide. Beneath the platform of passenger stations the arrangement is somewhat varied because of local obstructions, such as pipes, sewers, etc., of which it was necessary to take account in the construction of the stations. The plan shown on page 98, however, is typical.

The necessity of passing the cables from the 32 x 2 arrangement of ducts along the side of the tunnel to 8 x 8 and 16 x 4 arrangements of ducts beneath the passenger platforms involves serious difficulties in the proper support and protection of cables in manholes at the ends of the station platforms. In order to minimize the risk of interruption of service due to possible damage to a considerable number of cables in one of these manholes, resulting from short circuit in a single cable, all cables except at the joints are covered with two layers of asbestos aggregating a full 1/4-inch in thickness. This asbestos is specially prepared and is applied by wrapping the cable with two strips each 3 inches in width, the outer strip covering the line of junction between adjacent spirals of the inner strip, the whole when in place being impregnated with a solution of silicate of soda. The joints themselves are covered with two layers of asbestos held in place by steel tape applied spirally. To distribute the strains upon the cables in manholes, radical supports of various curvatures, and made of malleable cast iron, are used. The photograph on page 100 illustrates the arrangement of cables in one of these manholes.



In order to further diminish the risk of interruption of the service due to failure of power supply, each sub-station south of 96th Street receives its alternating current from the power house through cables carried on opposite sides of the subway. To protect the lead sheaths of the cables against damage by electrolysis, rubber insulating pieces 1/6 of an inch in thickness are placed between the sheaths and the iron bracket supports in the manholes.

[Sidenote: Cable Conveying Energy from Power House to Sub-Stations]

The cables used for conveying energy from the power house to the several sub-stations aggregate approximately 150 miles in length. The cable used for this purpose comprises three stranded copper conductors each of which contains nineteen wires, and the diameter of the stranded conductor thus formed is 2/5 of an inch. Paper insulation is employed and the triple cable is enclosed in a lead sheath 9/64 of an inch thick. Each conductor is separated from its neighbors and from the lead sheath by insulation of treated paper 7/16 of an inch in thickness. The outside diameter of the cables is 2-5/8 inches, and the weight 8-1/2 pounds per lineal foot. In the factories the cable as manufactured was cut into lengths corresponding to the distance between manholes, and each length subjected to severe tests including application to the insulation of an alternating current potential of 30,000 volts for a period of thirty minutes. These cables were installed under the supervision of the Interborough Company's engineers, and after jointing, each complete cable from power house to sub-station was tested by applying an alternating potential of 30,000 volts for thirty minutes between each conductor and its neighbors, and between each conductor and the lead sheath. The photographs on page 98 illustrates the construction of this cable.

[Sidenote: Sub-Station]

The tri-phase alternating current generated at the power house is conveyed through the high potential cable system to eight sub-stations containing the necessary transforming and converting machinery. These sub-stations are designed and located as follows:



Sub-station No. 11—29-33 City Hall Place.

Sub-station No. 12—108-110 East 19th Street.

Sub-station No. 13—225-227 West 53d Street.

Sub-station No. 14—264-266 West 96th Street.

Sub-station No. 15—606-608 West 143d Street.

Sub-station No. 16—73-77 West 132d Street.

Sub-station No. 17—Hillside Avenue, 301 feet West of Eleventh Avenue.

Sub-station No. 18—South side of Fox Street (Simpson Street), 60 feet north of Westchester Avenue.



The converter unit selected to receive the alternating current and deliver direct current to the track, etc., has an output of 1,500 kilowatts with ability to carry 50 per cent. overload for three hours. The average area of a city lot is 25 x 100 feet, and a sub-station site comprising two adjacent lots of this approximate size permits the installation of a maximum of eight 1,500 kilowatts converters with necessary transformers, switchboard and other auxiliary apparatus. In designing the sub-stations, a type of building with a central air-well was selected. The typical organization of apparatus is illustrated in the ground plan and vertical section on pages 101, 102 and 103 and provides, as shown, for two lines of converters, the three transformers which supply each converter being located between it and the adjacent side wall. The switchboard is located at the rear of the station. The central shaft affords excellent light and ventilation for the operating room. The steel work of the sub-stations is designed with a view to the addition of two storage battery floors, should it be decided at some future time that the addition of such an auxiliary is advisable.



The necessary equipment of the sub-stations implies sites approximately 50 x 100 feet in dimensions; and sub-stations Nos. 14, 15, 17, and 18 are practically all this size. Sub-stations Nos. 11 and 16 are 100 feet in length, but the lots acquired in these instances being of unusual width, these sub-stations are approximately 60 feet wide. Sub-station No. 12, on account of limited ground space, is but 48 feet wide and 92 feet long. In each of the sub-stations, except No. 13, foundations are provided for eight converters; sub-station No. 13 contains foundations for the ultimate installation of ten converters.



The function of the electrical apparatus in sub-stations, as has been stated, is the conversion of the high potential alternating current energy delivered from the power house through the tri-phase cables into direct current adapted to operate the motors with which the rolling stock is equipped. This apparatus comprises transformers, converters, and certain minor auxiliaries. The transformers, which are arranged in groups of three, receive the tri-phase alternating current at a potential approximating 10,500 volts, and deliver equivalent energy (less the loss of about 2 per cent. in the transformation) to the converters at a potential of about 390 volts. The converters receiving this energy from their respective groups of transformers in turn deliver it (less a loss approximating 4 per cent. at full load) in the form of direct current at a potential of 625 volts to the bus bars of the direct current switchboards, from which it is conveyed by insulated cables to the contact rails. The photograph on page 102 is a general view of the interior of one of the sub-stations. The exterior of sub-stations Nos. 11 and 18 are shown on page 107.



The illustration on page 108 is from a photograph taken on one of the switchboard galleries. In the sub-stations, as in the power house, the high potential alternating current circuits are opened and closed by oil switches, which are electrically operated by motors, these in turn being controlled by 110 volt direct current circuits. Diagramatic bench boards are used, as at the power house, but in the sub-stations they are of course relatively small and free from complication.

The instrument board is supported by iron columns and is carried at a sufficient height above the bench board to enable the operator, while facing the bench board and the instruments, to look out over the floor of the sub-station without turning his head. The switches of the direct current circuits are hand-operated and are located upon boards at the right and left of the control board.

A novel and important feature introduced (it is believed for the first time) in these sub-stations, is the location in separate brick compartments of the automatic circuit breakers in the direct current feeder circuits. These circuit breaker compartments are shown in the photograph on page 93, and are in a line facing the boards which carry the direct feeder switches, each circuit breaker being located in a compartment directly opposite the panel which carries the switch belonging to the corresponding circuit. This plan will effectually prevent damage to other parts of the switchboard equipment when circuit-breakers open automatically under conditions of short-circuit. It also tends to eliminate risk to the operator, and, therefore, to increase his confidence and accuracy in manipulating the hand-operated switches.



The three conductor cables which convey tri-phase currents from the power house are carried through tile ducts from the manholes located in the street directly in front of each sub-station to the back of the station where the end of the cable is connected directly beneath its oil switch. The three conductors, now well separated, extend vertically to the fixed terminals of the switch. In each sub-station but one set of high-potential alternating current bus bars is installed and between each incoming cable and these bus bars is connected an oil switch. In like manner, between each converter unit and the bus bars an oil switch is connected into the high potential circuit. The bus bars are so arranged that they may be divided into any number of sections not exceeding the number of converter units, by means of movable links which, in their normal condition, constitute a part of the bus bars.

Each of the oil switches between incoming circuits and bus bars is arranged for automatic operation and is equipped with a reversed current relay, which, in the case of a short-circuit in its alternating current feeder cable opens the switch and so disconnects the cable from the sub-station without interference with the operation of the other cables or the converting machinery.



[Sidenote: Direct Current Distribution from Sub-Stations]

The organization of electrical conductors provided to convey direct current from the sub-stations to the moving trains can be described most conveniently by beginning with the contact, or so-called third rail. South of 96th Street the average distance between sub-stations approximates 12,000 feet, and north of 96th Street the average distance is about 15,000 feet. Each track, of course, is provided with a contact rail. There are four tracks and consequently four contact rails from City Hall to 96th Street, three from 96th Street to 145th Street on the West Side, two from 145th Street to Dyckman Street, and three from Dyckman Street to the northern terminal of the West Side extension of the system. From 96th Street, the East Side has two tracks and two contact rails to Mott Avenue, and from that point to the terminal at 182d Street three tracks and three contact rails.



Contact rails south of Reade Street are supplied from sub-station No. 11; from Reade Street to 19th Street they are supplied from sub-stations Nos. 11 and 12; from 19th Street they are supplied from sub-stations Nos. 12 and 13; from the point last named to 96th Street they are supplied from sub-stations Nos. 13 and 14; from 96th Street to 143d Street, on the West Side, they are supplied from sub-stations Nos. 14 and 15; from 143d Street to Dyckman Street they are supplied from sub-stations Nos. 15 and 17; and from that point to the terminal they are supplied from sub-station No. 17. On the East Side branch contact rails from 96th Street to 132d Street are supplied from sub-stations Nos. 14 and 16; from 132d to 165th Street they are supplied from sub-stations Nos. 16 and 18; and from 165th Street to 182d Street they are supplied from sub-station No. 18.

Each contact rail is insulated from all contact rails belonging to adjacent tracks. This is done in order that in case of derailment or other accident necessitating interruption of service on a given track, trains may be operated upon the other tracks having their separate and independent channels of electrical supply. To make this clear, we may consider that section of the subway which lies between Reade Street and 19th Street. This section is equipped with four tracks, and the contact rail for each track, together with the direct current feeders which supply it from sub-stations Nos. 11 and 12, are electrically insulated from all other circuits. Of each pair of track rails one is used for the automatic block signaling system, and, therefore, is not used as a part of the negative or return side of the direct current system. The other four track rails, however, are bonded, and together with the negative feeders constitute the track return or negative side of the direct current system.

The diagram on page 109 illustrates the connections of the contact rails, track rails and the positive and negative feeders. All negative as well as positive feeders are cables of 2,000,000 c. m. section and lead sheathed. In emergency, as, for example, in the case of the destruction of a number of the cables in a manhole, they are, therefore, interchangeable. The connections are such as to minimize "track drop," as will be evident upon examination of the diagram. The electrical separation of the several contact rails and the positive feeders connected thereto secures a further important advantage in permitting the use at sub-stations of direct-current circuit-breakers of moderate size and capacity, which can be set to open automatically at much lower currents than would be practicable were all contact rails electrically connected, thus reducing the limiting current and consequently the intensity of the arcs which might occur in the subway in case of short-circuit between contact rail and earth.

The contact rail itself is of special soft steel, to secure high conductivity. Its composition, as shown by tests, is as follows: Carbon, .08 to .15; silicon, .05; phosphorus, .10; manganese, .50 to .70; and sulphur, .05. Its resistance is not more than eight times the resistance of pure copper of equal cross-section. The section chosen weighs 75 pounds per yard. The length used in general is 60 feet, but in some cases 40 feet lengths are substituted. The contact rails are bounded by four bonds, aggregating 1,200,000 c. m. section. The bonds are of flexible copper and their terminals are riveted to the steel by hydraulic presses, producing a pressure of 35 tons. The bonds when in use are covered by special malleable iron fish-plates which insure alignment of rail. Each length of rail is anchored at its middle point and a small clearance is allowed between ends of adjacent rails for expansion and contraction, which in the subway, owing to the relatively small change of temperature, will be reduced to a minimum. The photographs on pages 110 and 111 illustrate the method of bonding the rail, and show the bonded joint completed by the addition of the fish-plates.

The contact rail is carried upon block insulators supported upon malleable iron castings. Castings of the same material are used to secure the contact rail in position upon the insulators. A photograph of the insulator with its castings is shown on page 113.

[Sidenote: Track Bonding]

The track rails are 33 feet long, of Standard American Society Civil Engineers' section, weighing 100 pounds a yard. As has been stated, one rail in each track is used for signal purposes and the other is utilized as a part of the negative return of the power system. Adjacent rails to be used for the latter purpose are bonded with two copper bonds having an aggregate section of 400,000 c. m. These bonds are firmly riveted into the web of the rail by screw bonding presses. They are covered by splice bars, designed to leave sufficient clearance for the bond.

The return rails are cross-sectioned at frequent intervals for the purpose of equalizing currents which traverse them.

[Sidenote: Contact Rail Guard and Collector Shoe]

The Interborough Company has provided a guard in the form of a plank 8-1/2 inches wide and 1-1/2 inches thick, which is supported in a horizontal position directly above the rail, as shown in the illustration on page 113. This guard is carried by the contact rail to which it is secured by supports, the construction of which is sufficiently shown in the illustration. This type of guard has been in successful use upon the Wilkesbarre and Hazleton Railway for nearly two years. It practically eliminates the danger from the third rail, even should passengers leave the trains and walk through a section of the tunnel while the rails are charged.

Its adoption necessitates the use of a collecting shoe differing radically from that used upon the Manhattan division and upon the elevated railways employing the third rail system in Chicago, Boston, Brooklyn, and elsewhere. The shoe is shown in the photograph on page 114. The shoe is held in contact with the third rail by gravity reinforced by pressure from two spiral springs. The support for the shoe includes provision for vertical adjustment to compensate for wear of car wheels, etc.



CHAPTER VI

ELECTRICAL EQUIPMENT OF CARS

In determining the electrical equipment of the trains, the company has aimed to secure an organization of motors and control apparatus easily adequate to operate trains in both local and express service at the highest speeds compatible with safety to the traveling public. For each of the two classes of service the limiting safe speed is fixed by the distance between stations at which the trains stop, by curves, and by grades. Except in a few places, for example where the East Side branch passes under the Harlem River, the tracks are so nearly level that the consideration of grade does not materially affect determination of the limiting speed. While the majority of the curves are of large radius, the safe limiting speed, particularly for the express service, is necessarily considerably less than it would be on straight tracks.

The average speed of express trains between City Hall and 145th Street on the West Side will approximate 25 miles an hour, including stops. The maximum speed of trains will be 45 miles per hour. The average speed of local and express trains will exceed the speed made by the trains on any elevated railroad.

To attain these speeds without exceeding maximum safe limiting speeds between stops, the equipment provided will accelerate trains carrying maximum load at a rate of 1.25 miles per hour per second in starting from stations on level track. To obtain the same acceleration by locomotives, a draw-bar pull of 44,000 pounds would be necessary—a pull equivalent to the maximum effect of six steam locomotives such as were used recently upon the Manhattan Elevated Railway in New York, and equivalent to the pull which can be exerted by two passenger locomotives of the latest Pennsylvania Railroad type. Two of these latter would weigh about 250 net tons. By the use of the multiple unit system of electrical control, equivalent results in respect to rate of acceleration and speed are attained, the total addition to train weight aggregating but 55 net tons.

If the locomotive principle of train operation were adopted, therefore, it is obvious that it would be necessary to employ a lower rate of acceleration for express trains. This could be attained without very material sacrifice of average speed, since the average distance between express stations is nearly two miles. In the case of local trains, however, which average nearly three stops per mile, no considerable reduction in the acceleration is possible without a material reduction in average speed. The weight of a local train exceeds the weight of five trail cars, similarly loaded, by 33 net tons, and equivalent adhesion and acceleration would require locomotives having not less than 80 net tons effective upon drivers.

[Sidenote: Switching]

The multiple unit system adopted possesses material advantages over a locomotive system in respect to switching at terminals. Some of the express trains in rush hours will comprise eight cars, but at certain times during the day and night when the number of people requiring transportation is less than during the morning and evening, and were locomotives used an enormous amount of switching, coupling and uncoupling would be involved by the comparative frequent changes of train lengths. In an eight-car multiple-unit express train, the first, third, fifth, sixth, and eighth cars will be motor cars, while the second, fourth, and seventh will be trail cars. An eight-car train can be reduced, therefore, to a six-car train by uncoupling two cars from either end, to a five-car train by uncoupling three cars from the rear end, or to a three-car train by uncoupling five cars from either end. In each case a motor car will remain at each end of the reduced train. In like manner, a five-car local train may be reduced to three cars, still leaving a motor car at each end by uncoupling two cars from either end, since in the normal five-car local train the first, third, and fifth cars will be motor cars.



[Sidenote: Motors]

The motors are of the direct current series type and are rated 200 horse power each. They have been especially designed for the subway service in line with specifications prepared by engineers of the Interborough Company, and will operate at an average effective potential of 570 volts. They are supplied by two manufacturers and differ in respect to important features of design and construction, but both are believed to be thoroughly adequate for the intended service.



The photographs on this page illustrate motors of each make. The weight of one make complete, with gear and gear case, is 5,900 pounds. The corresponding weight of the other is 5,750 pounds. The ratio of gear reduction used with one motor is 19 to 63, and with the other motor 20 to 63.



[Sidenote: Motor Control]

By the system of motor control adopted for the trains, the power delivered to the various motors throughout the train is simultaneously controlled and regulated by the motorman at the head of the train. This is accomplished by means of a system of electric circuits comprising essentially a small drum controller and an organization of actuating circuits conveying small currents which energize electric magnets placed beneath the cars, and so open and close the main power circuits which supply energy to the motors. A controller is mounted upon the platform at each end of each motor car, and the entire train may be operated from any one of the points, the motorman normally taking his post on the front platform of the first car. The switches which open and close the power circuits through motors and rheostats are called contactors, each comprising a magnetic blow-out switch and the electro magnet which controls the movements of the switch. By these contactors the usual series-multiple control of direct-current motors is effected. The primary or control circuits regulate the movement, not only of the contactors but also of the reverser, by means of which the direction of the current supplied to motors may be reversed at the will of the motorman.



The photograph on this page shows the complete control wiring and motor equipment of a motor car as seen beneath the car. In wiring the cars unusual precautions have been adopted to guard against risk of fire. As elsewhere described in this publication, the floors of all motor cars are protected by sheet steel and a material composed of asbestos and silicate of soda, which possesses great heat-resisting properties. In addition to this, all of the important power wires beneath the car are placed in conduits of fireproof material, of which asbestos is the principal constituent. Furthermore, the vulcanized rubber insulation of the wires themselves is covered with a special braid of asbestos, and in order to diminish the amount of combustible insulating material, the highest grade of vulcanized rubber has been used, and the thickness of the insulation correspondingly reduced. It is confidently believed that the woodwork of the car body proper cannot be seriously endangered by an accident to the electric apparatus beneath the car. Insulation is necessarily combustible, and in burning evolves much smoke; occasional accidents to the apparatus, notwithstanding every possible precaution, will sometimes happen; and in the subway the flash even of an absolutely insignificant fuse may be clearly visible and cause alarm. The public traveling in the subway should remember that even very severe short-circuits and extremely bright flashes beneath the car involve absolutely no danger to passengers who remain inside the car.

The photograph on page 120 illustrates the control wiring of the new steel motorcars. The method of assembling the apparatus differs materially from that adopted in wiring the outfit of cars first ordered, and, as the result of greater compactness which has been attained, the aggregate length of the wiring has been reduced one-third.

The quality and thickness of the insulation is the same as in the case of the earlier cars, but the use of asbestos conduits is abandoned and iron pipe substituted. In every respect it is believed that the design and workmanship employed in mounting and wiring the motors and control equipments under these steel cars is unequaled elsewhere in similar work up to the present time.



The motors and car wiring are protected by a carefully planned system of fuses, the function of which is to melt and open the circuits, so cutting off power in case of failure of insulation.

Express trains and local trains alike are provided with a bus line, which interconnects the electrical supply to all cars and prevents interruption of the delivery of current to motors in case the collector shoes attached to any given car should momentarily fail to make contact with the third rail. At certain cross-overs this operates to prevent extinguishing the lamps in successive cars as the train passes from one track to another. The controller is so constructed that when the train is in motion the motorman is compelled to keep his hand upon it, otherwise the power is automatically cut off and the brakes are applied. This important safety device, which, in case a motorman be suddenly incapacitated at his post, will promptly stop the train, is a recent invention and is first introduced in practical service upon trains of the Interborough Company.

[Sidenote: Heating and Lighting]

All cars are heated and lighted by electricity. The heaters are placed beneath the seats, and special precautions have been taken to insure uniform distribution of the heat. The wiring for heaters and lights has been practically safe-guarded to avoid, so far as possible, all risk of short-circuit or fire, the wire used for the heater circuits being carried upon porcelain insulators from all woodwork by large clearances, while the wiring for lights is carried in metallic conduit. All lamp sockets are specially designed to prevent possibility of fire and are separated from the woodwork of the car by air spaces and by asbestos.



The interior of each car is lighted by twenty-six 10-candle power lamps, in addition to four lamps provided for platforms and markers. The lamps for lighting the interior are carefully located, with a view to securing uniform and effective illumination.



CHAPTER VII

LIGHTING SYSTEM FOR PASSENGER STATIONS AND TUNNEL

In the initial preparation of plans, and more than a year before the accident which occurred in the subway system of Paris in August, 1903, the engineers of the Interborough Company realized the importance of maintaining lights in the subway independent of any temporary interruption of the power used for lighting the cars, and, in preparing their plans, they provided for lighting the subway throughout its length from a source independent of the main power supply. For this purpose three 1,250-kilowatt alternators direct-driven by steam turbines are installed in the power house, from which point a system of primary cables, transformers and secondary conductors convey current to the incandescent lamps used solely to light the subway. The alternators are of the three-phase type, making 1,200 revolutions per minute and delivering current at a frequency of 60 cycles per second at a potential of 11,000 volts. In the boiler plant and system of steam piping installed in connection with these turbine-driven units, provision is made for separation of the steam supply from the general supply for the 5,000 kilowatt units and for furnishing the steam for the turbine units through either of two alternative lines of pipe.

The 11,000-volt primary current is conveyed through paper insulated lead-sheathed cables to transformers, located in fireproof compartments adjacent to the platforms of the passenger stations. These transformers deliver current to two separate systems of secondary wiring, one of which is supplied at a potential of 120 volts and the other at 600 volts.

The general lighting of the passenger station platforms is effected by incandescent lamps supplied from the 120-volt secondary wiring circuits, while the lighting of the subway sections between adjacent stations is accomplished by incandescent lamps connected in series groups of five each and connected to the 600-volt lighting circuits. Recognizing the fact that in view of the precautions taken it is probable that interruptions of the alternating current lighting service will be infrequent, the possibility of such interruption is nevertheless provided for by installing upon the stairways leading to passenger station platforms, at the ticket booths and over the tracks in front of the platforms, a number of lamps which are connected to the contact rail circuit. This will provide light sufficient to enable passengers to see stairways and the edges of the station platforms in case of temporary failure of the general lighting system.

The general illumination of the passenger stations is effected by means of 32 c. p. incandescent lamps, placed in recessed domes in the ceiling. These are reinforced by 14 c. p. and 32 c. p. lamps, carried by brackets of ornate design where the construction of the station does not conveniently permit the use of ceiling lights. The lamps are enclosed in sand-blasted glass globes, and excellent distribution is secured by the use of reflectors.

The illustration on page 122 is produced from a photograph of the interior of one of the transformer cupboards and shows the transformer in place with the end bell of the high potential cable and the primary switchboard containing switches and enclosed fuses. The illustration on page 123 shows one of the secondary distributing switchboards which are located immediately behind the ticket booths, where they are under the control of the ticket seller.



In lighting the subway between passenger stations, it is desirable, on the one hand, to provide sufficient light for track inspection and to permit employees passing along the subway to see their way clearly and avoid obstructions; but, on the other hand, the lighting must not be so brilliant as to interfere with easy sight and recognition of the red, yellow, and green signal lamps of the block signal system. It is necessary also that the lights for general illumination be so placed that their rays shall not fall directly upon the eyes of approaching motormen at the head of trains nor annoy passengers who may be reading their papers inside the cars. The conditions imposed by these considerations are met in the four-track sections of the subway by placing a row of incandescent lamps between the north-bound local and express tracks and a similar row between the southbound local and express tracks. The lamps are carried upon brackets supported upon the iron columns of the subway structure, successive lamps in each row being 60 feet apart. They are located a few inches above the tops of the car windows and with reference to the direction of approaching trains the lamps in each row are carried upon the far side of the iron columns, by which expedient the eyes of the approaching motormen are sufficiently protected against their direct rays.

[Sidenote: Lighting of the Power House]

For the general illumination of the engine room, clusters of Nernst lamps are supported from the roof trusses and a row of single lamps of the same type is carried on the lower gallery about 25 feet from the floor. This is the first power house in America to be illuminated by these lamps. The quality of the light is unsurpassed and the general effect of the illumination most satisfactory and agreeable to the eye. In addition to the Nernst lamps, 16 c. p. incandescent lamps are placed upon the engines and along the galleries in places not conveniently reached by the general illumination. The basement also is lighted by incandescent lamps.



For the boiler room, a row of Nernst lamps in front of the batteries of boilers is provided, and, in addition to these, incandescent lamps are used in the passageways around the boilers, at gauges and at water columns. The basement of the boiler room, the pump room, the economizer floor, coal bunkers, and coal conveyers are lighted by incandescent lamps, while arc lamps are used around the coal tower and dock. The lights on the engines and those at gauge glasses and water columns and at the pumps are supplied by direct current from the 250-volt circuits. All other incandescent lamps and the Nernst lamps are supplied through transformers from the 60-cycle lighting system.

[Sidenote: Emergency Signal System and Provision for Cutting Off Power from Contact Rail]

In the booth of each ticket seller and at every manhole along the west side of the subway and its branches is placed a glass-covered box of the kind generally used in large American cities for fire alarm purposes. In case of accident in the subway which may render it desirable to cut off power from the contact rails, this result can be accomplished by breaking the glass front of the emergency box and pulling the hook provided. Special emergency circuits are so arranged that pulling the hook will instantly open all the circuit-breakers at adjacent sub-stations through which the contact rails in the section affected receive their supply of power. It will also instantly report the location of the trouble, annunciator gongs being located in the sub-stations from which power is supplied to the section, in the train dispatchers' offices and in the office of the General Superintendent, instantly intimating the number of the box which has been pulled. Automatic recording devices in train dispatchers' offices and in the office of the General Superintendent also note the number of the box pulled.

The photograph on page 120 shows a typical fire alarm box.



CHAPTER VIII

ROLLING STOCK—CARS, TRUCKS, ETC.

The determination of the builders of the road to improve upon the best devices known in electrical railroading and to provide an equipment unequaled on any interurban line is nowhere better illustrated than in the careful study given to the types of cars and trucks used on other lines before a selection was made of those to be employed on the subway.

All of the existing rapid transit railways in this country, and many of those abroad, were visited and the different patterns of cars in use were considered in this investigation, which included a study of the relative advantages of long and short cars, single and multiple side entrance cars and end entrance cars, and all of the other varieties which have been adopted for rapid transit service abroad and at home.

The service requirement of the New York subway introduces a number of unprecedented conditions, and required a complete redesign of all the existing models. The general considerations to be met included the following:

High schedule speeds with frequent stops.

Maximum carrying capacity for the subway, especially at times of rush hours, morning and evening.

Maximum strength combined with smallest permissible weight.

Adoption of all precautions calculated to reduce possibility of damage from either the electric circuit or from collisions.

The clearance and length of the local station platforms limited the length of trains, and tunnel clearances the length and width and height of the cars.

The speeds called for by the contract with the city introduced motive power requirements which were unprecedented in any existing railway service, either steam or electric, and demanded a minimum weight consistent with safety. As an example, it may be stated that an express train of eight cars in the subway to conform to the schedule speed adopted will require a nominal power of motors on the train of 2,000 horse power, with an average accelerating current at 600 volts in starting from a station stop of 325 amperes. This rate of energy absorption which corresponds to 2,500 horse power is not far from double that taken by the heaviest trains on trunk line railroads when starting from stations at the maximum rate of acceleration possible with the most powerful modern steam locomotives.

Such exacting schedule conditions as those mentioned necessitated the design of cars, trucks, etc., of equivalent strength to that found in steam railroad car and locomotive construction, so that while it was essential to keep down the weight of the train and individual cars to a minimum, owing to the frequent stops, it was equally as essential to provide the strongest and most substantial type of car construction throughout.

Owing to these two essentials which were embodied in their construction it can safely be asserted that the cars used in the subway represent the acme of car building art as it exists to-day, and that all available appliances for securing strength and durability in the cars and immunity from accidents have been introduced.

After having ascertained the general type of cars which would be best adapted to the subway service, and before placing the order for car equipments, it was decided to build sample cars embodying the approved principles of design. From these the management believed that the details of construction could be more perfectly determined than in any other way. Consequently, in the early part of 1902, two sample cars were built and equipped with a variety of appliances and furnishings so that the final type could be intelligently selected. From the tests conducted on these cars the adopted type of car which is described in detail below was evolved.

After the design had been worked out a great deal of difficulty was encountered in securing satisfactory contracts for proper deliveries, on account of the congested condition of the car building works in the country. Contracts were finally closed, however, in December, 1902, for 500 cars, and orders were distributed between four car-building firms. Of these cars, some 200, as fast as delivered, were placed in operation on the Second Avenue line of the Elevated Railway, in order that they might be thoroughly tested during the winter of 1903-4.



In view of the peculiar traffic conditions existing in New York City and the restricted siding and yard room available in the subway, it was decided that one standard type of car for all classes of service would introduce the most flexible operating conditions, and for this reason would best suit the public demands at different seasons of the year and hours of the day. In order further to provide cars, each of which would be as safe as the others, it was essential that there should be no difference in constructional strength between the motor cars and the trail cars. All cars were therefore made of one type and can be used interchangeably for either motor or trail-car service.

The motor cars carry both motors on the same truck; that is, they have a motor truck at one end carrying two motors, one geared to each axle; the truck at the other end of the car is a "trailer" and carries no motive power.



Some leading distinctive features of the cars may be enumerated as follows:

(1.) The length is 51 feet and provides seating capacity for 52 passengers. This length is about 4 feet more than those of the existing Manhattan Elevated Railroad cars.

(2.) The enclosed vestibule platforms with sliding doors instead of the usual gates. The enclosed platforms will contribute greatly to the comfort and safety of passengers under subway conditions.

(3.) The anti-telescoping car bulkheads and platform posts. This construction is similar to that in use on Pullman cars, and has been demonstrated in steam railroad service to be an important safety appliance.

(4.) The steel underframing of the car, which provides a rigid and durable bed structure for transmitting the heavy motive power stresses.

(5.) The numerous protective devices against defects in the electrical apparatus.

(6.) Window arrangement, permitting circulation without draughts.

(7.) Emergency brake valve on truck operated by track trip.

(8.) Emergency brake valve in connection with master-controller.

The table on page 133 shows the main dimensions of the car, and also the corresponding dimensions of the standard car in use on the Manhattan Elevated Railway.

The general arrangement of the floor framing is well shown in the photograph on page 132. The side sills are of 6-inch channels, which are reinforced inside and out by white oak timbers. The center sills are 5-inch I-beams, faced on both sides with Southern pine. The end sills are also of steel shapes, securely attached to the side sills by steel castings and forgings. The car body end-sill channel is faced with a white-oak filler, mortised to receive the car body end-posts and braced at each end by gusset plates. The body bolster is made up of two rolled steel plates bolted together at their ends and supported by a steel draw casting, the ends of which form a support for the center sills. The cross-bridging and needle-beams of 5-inch I-beams are unusually substantial. The flooring inside the car is double and of maple, with asbestos fire-felt between the layers, and is protected below by steel plates and "transite" (asbestos board).

The side framing of the car is of white ash, doubly braced and heavily trussed. There are seven composite wrought-iron carlines forged in shape for the roof, each sandwiched between two white ash carlines, and with white ash intermediate carlines. The platform posts are of compound construction with anti-telescoping posts of steel bar sandwiched between white ash posts at corners and centers of vestibuled platforms. These posts are securely bolted to the steel longitudinal sills, the steel anti-telescoping plate below the floor, and to the hood of the bow which serves to reinforce it. This bow is a heavy steel angle in one piece, reaching from plate to plate and extending back into the car 6 feet on each side. By this construction it is believed that the car framing is practically indestructible. In case of accident, if one platform should ride over another, eight square inches of metal would have to be sheared off the posts before the main body of the car would be reached, which would afford an effective means of protection.



The floor is completely covered on the underside with 1/4-inch asbestos transite board, while all parts of the car framing, flooring, and sheathing are covered with fire-proofing compound. In addition, all spaces above the motor truck in the floor framing, between sills and bridging, are protected by plates of No. 8 steel and 1/4-inch roll fire-felt extending from the platform end sill to the bolster.

[Sidenote: Car Wiring]

The precautions to secure safety from fire consists generally in the perfected arrangement and installation of the electrical apparatus and the wiring. For the lighting circuits a flexible steel conduit is used, and a special junction box. On the side and upper roofs, over these conduits for the lighting circuits, a strip of sheet iron is securely nailed to the roof boards before the canvas is applied. The wires under the floor are carried in ducts moulded into suitable forms of asbestos compound. Special precautions have been taken with the insulation of the wires, the specifications calling for, first, a layer of paper, next, a layer of rubber, and then a layer of cotton saturated with a weather-proof compound, and outside of this a layer of asbestos. The hangers supporting the rheostats under the car body are insulated with wooden blocks, treated by a special process, being dried out in an oven and then soaked in an insulating compound, and covered with 1/4-inch "transite" board. The rheostat boxes themselves are also insulated from the angle iron supporting them. Where the wires pass through the flooring they are hermetically sealed to prevent the admission of dust and dirt.

At the forward end of what is known as the No. 1 end of the car all the wires are carried to a slate switchboard in the motorman's cab. This board is 44 x 27 inches, and is mounted directly back of the motorman. The window space occupied by this board is ceiled up and the space back of the panels is boxed in and provided with a door of steel plate, forming a box, the cover, top, bottom, and sides of which are lined with electrobestos 1/2-inch thick. All of the switches and fuses, except the main trolley fuse and bus-line fuse, which are encased and placed under the car, are carried on this switchboard. Where the wires are carried through the floor or any partition, a steel chute, lined with electrobestos, is used to protect the wires against mechanical injury. It will be noted from the above that no power wiring, switches, or fuses are placed in the car itself, all such devices being outside in a special steel insulated compartment.

A novel feature in the construction of these cars is the motorman's compartment and vestibule, which differs essentially from that used heretofore, and the patents are owned by the Interborough Company. The cab is located on the platform, so that no space within the car is required; at the same time the entire platform space is available for ingress and egress except that on the front platform of the first car, on which the passengers would not be allowed in any case. The side of the cab is formed by a door which can be placed in three positions. When in its mid-position it encloses a part of the platform, so as to furnish a cab for the motorman, but when swung parallel to the end sills it encloses the end of the platform, and this would be its position on the rear platform of the rear car. The third position is when it is swung around to an arc of 180 degrees, when it can be locked in position against the corner vestibule post enclosing the master controller. This would be its position on all platforms except on the front of the front car or the rear of the rear car of the train.

The platforms themselves are not equipped with side gates, but with doors arranged to slide into pockets in the side framing, thereby giving up the entire platform to the passengers. These doors are closed by an overhead lever system. The sliding door on the front platform of the first car may be partly opened and secured in this position by a bar, and thus serve as an arm-rest for the motorman. The doors close against an air-cushion stop, making it impossible to clutch the clothing or limbs of passengers in closing.



Pantagraph safety gates for coupling between cars are provided. They are constructed so as to adjust themselves to suit the various positions of adjoining cars while passing in, around, and out of curves of 90 feet radius.

On the door leading from the vestibule to the body of the car is a curtain that can be automatically raised and lowered as the door is opened or closed to shut the light away from the motorman. Another attachment is the peculiar handle on the sliding door. This door is made to latch so that it cannot slide open with the swaying of the car, but the handle is so constructed that when pressure is applied upon it to open the door, the same movement will unlatch it.

Entering the car, the observer is at once impressed by the amount of room available for passengers. The seating arrangements are similar to the elevated cars, but the subway coaches are longer and wider than the Manhattan, and there are two additional seats on each end. The seats are all finished in rattan. Stationary crosswise seats are provided after the Manhattan pattern, at the center of the car. The longitudinal seats are 17-3/4 inches deep. The space between the longitudinal seats is 4 feet 5 inches.

The windows have two sashes, the lower one being stationary, while the upper one is a drop sash. This arrangement reverses the ordinary practice, and is desirable in subway operation and to insure safety and comfort to the passengers. The side windows in the body of the car, also the end windows and end doors, are provided with roll shades with pinch-handle fixtures.



The floors are covered with hard maple strips, securely fastened to the floor with ovalhead brass screws, thus providing a clean, dry floor for all conditions of weather.

Six single incandescent lamps are placed on the upper deck ceiling, and a row of ten on each side deck ceiling is provided. There are two lamps placed in a white porcelain dome over each platform, and the pressure gauge is also provided with a miniature lamp.



The head linings are of composite board. The interior finish is of mahogany of light color. A mahogany handrail extends the full length of the clerestory on each side of the car, supported in brass sockets at the ends and by heavy brass brackets on each side. The handrail on each side of the car carries thirty-eight leather straps.

Each ventilator sash is secured on the inside to a brass operating arm, manipulated by means of rods running along each side of the clerestory, and each rod is operated by means of a brass lever, having a fulcrum secured to the inside of the clerestory.

All hardware is of bronze, of best quality and heavy pattern, including locks, pulls, handles, sash fittings, window guards, railing brackets and sockets, bell cord thimbles, chafing strips, hinges, and all other trimmings. The upright panels between the windows and the corner of the car are of plain mahogany, as are also the single post pilasters, all of which are decorated with marquetry inlaid. The end finish is of mahogany, forming a casing for the end door.



[Sidenote: Steel Cars]

At the time of placing the first contract for the rolling stock of the subway, the question of using an all-steel car was carefully considered by the management. Such a type of car, in many respects, presented desirable features for subway work as representing the ultimate of absolute incombustibility. Certain practical reasons, however, prevented the adoption of an all-steel car in the spring of 1902 when it became necessary to place the orders mentioned above for the first 500 cars. Principal among these reasons was the fact that no cars of this kind had ever been constructed, and as the car building works of the country were in a very congested condition all of the larger companies declined to consider any standard specifications even for a short-time delivery, while for cars involving the extensive use of metal the question was impossible of immediate solution. Again, there were a number of very serious mechanical difficulties to be studied and overcome in the construction of such a car, such as avoidance of excessive weight, a serious element in a rapid transit service, insulation from the extremes of heat and cold, and the prevention of undue noise in operation. It was decided, therefore, to bend all energies to the production of a wooden car with sufficient metal for strength and protection from accident, i. e., a stronger, safer, and better constructed car than had heretofore been put in use on any electric railway in the world. These properties it is believed are embodied in the car which has just been described.



The plan of an all-metal car, however, was not abandoned, and although none was in use in passenger service anywhere, steps were immediately taken to design a car of this type and conduct the necessary tests to determine whether it would be suitable for railway service. None of the car-building companies was willing to undertake the work, but the courteous cooeperation of the Pennsylvania Railroad Company was secured in placing its manufacturing facilities at Altoona at the disposal of the Interborough Rapid Transit Railway Company. Plans were prepared for an all-metal car, and after about fourteen months of work a sample type was completed in December, 1903, which was in every way creditable as a first attempt.

The sample car naturally embodied some faults which only experience could correct, the principal one being that the car was not only too heavy for use on the elevated lines of the company, but attained an undesirable weight for subway operation. From this original design, however, a second design involving very original features has been worked out, and a contract has been given by the Interborough Company for 200 all-steel cars, which are now being constructed. While the expense of producing this new type of car has obviously been great, this consideration has not influenced the management of the company in developing an equipment which promised the maximum of operating safety.



[Sidenote: The General Arrangements]

The general dimensions of the all-steel car differ only slightly from those of the wooden car. The following table gives the dimensions of the two cars, and also that of the Manhattan Railway cars:

Wooden All-Steel Manhattan Cars. Cars. Cars.

Length over body corner posts, 42' 7" 41' 1/2" 39' 10"

Length over buffers, 51' 2" 51' 2" 47' 1"

Length over draw-bars, 51' 5" 51' 5" 47' 4"

Width over side sills, 8' 8-3/8" 8' 6-3/4" 8' 6"

Width over sheathing, 8' 10" 8' 7" 8' 7"

Width over window sills, 8' 11-7/8" 9' 1/2" 8' 9"

Width over battens, 8' 10-3/4" 8' 7-1/4" 8' 7-7/8"

Width over eaves, 8' 8" 8' 8" 8' 9-1/2"

Height from under side of sill to top of plate, 7' 3-1/8" 7' 1" 7' 3"

Height of body from under side of center sill to top of roof, 8' 9-7/8" 8' 9-7/8" 9' 5-7/8"

Height of truck from rail to top of truck center plate (car light), 2' 8" 2' 8" 2' 5-3/4"

Height from top of rail to underside of side sill at truck center (car light), 3' 1-1/8" 3' 2-1/8" 3' 3-1/4"

Height from top of rail to top of roof not to exceed (car light), 12' 3/4" 12' 0" 12' 10-1/2"

The general frame plan of the all-steel car is clearly shown by the photograph on page 128. As will be seen, the floor framing is made up of two center longitudinal 6-inch I-beams and two longitudinal 5 x 3-inch steel side angles, extending in one piece from platform-end sill to platform-end sill. The end sills are angles and are secured to the side and center sills by cast-steel brackets, and in addition by steel anti-telescoping plates, which are placed on the under side of the sills and riveted thereto. The flooring is of galvanized, corrugated sheet iron, laid across the longitudinal sills and secured to longitudinal angles by rivets. This corrugated sheet holds the fireproof cement flooring called "monolith." On top of this latter are attached longitudinal floor strips for a wearing surface. The platform flooring is of steel plate covered with rubber matting cemented to the same. The side and end frame is composed of single and compound posts made of steel angles or T's and the roof framing of wrought-iron carlines and purlines. The sides of the cars are double and composed of steel plates on the outside, riveted to the side posts and belt rails, and lined with electrobestos. The outside roof is of fireproof composite board, covered with canvas. The headlinings are of fireproof composite, faced with aluminum sheets. The mouldings throughout are of aluminum. The wainscoting is of "transite" board and aluminum, and the end finish and window panels are of aluminum, lined with asbestos felt. The seat frames are of steel throughout, as are also the cushion frames. The sash is double, the lower part being stationary and the upper part movable. The doors are of mahogany, and are of the sliding type and are operated by the door operating device already described.



[Sidenote: Trucks]

Two types of trucks are being built, one for the motor end, the other for the trailer end of the car. The following are the principal dimensions of the trucks:

Motor Truck. Trailer Truck.

Gauge of track,............................. 4' 8-1/2" 4' 8-1/2" Distance between backs of wheel flanges,.... 4' 5-3/8" 4' 5-3/8" Height of truck center plate above rail, car body loaded with 15,000 pounds,....... 30" 30" Height of truck side bearings above rail, car body loaded,.......................... 34" 34" Wheel base of truck,........................ 6' 8" 5' 6" Weight on center plate with car body loaded, about............................. 27,000 lbs. Side frames, wrought-iron forged,........... 2-1/2" x 4" 1-1/2" x 3" Pedestals, wrought-iron forged,......................... Center transom, steel channel,.......................... Truck bolster,.............................. cast steel. wood and iron. Equalizing bars, wrought iron,.......................... Center plate, cast steel,............................... Spring plank, wrought iron,................. 1" x 3" white oak. Bolster springs, elliptic, length, ......... 30" 32" Equalizing springs, double coil, outside dimensions,................... 4-7/8" x 7-1/2" 3-5/8" x 6" Wheels, cast steel spoke center, steel tired, diameter,.................... 33-3/4" 30" Tires, tread M. C. B. Standard,......... 2-5/8" x 5-1/4" 2-5/8" x 5-1/4" Axles, diameter at center,.................. 6-1/2" 4-3/4" Axles, diameter at gear seat,............... 7-13/16" Axles, diameter at wheel seat,.............. 7-3/4" 5-3/4" Journals,................................... 5" x 9" 4-1/4" x 8" Journal boxes, malleable iron, M. C. B. Standard,....................................

Both the motor and the trailer trucks have been designed with the greatest care for severe service, and their details are the outcome of years of practical experience.



CHAPTER IX

SIGNAL SYSTEM

Early in the development of the plans for the subway system in New York City, it was foreseen that the efficiency of operation of a road with so heavy a traffic as is being provided for would depend largely upon the completeness of the block signaling and interlocking systems adopted for spacing and directing trains. On account of the importance of this consideration, not only for safety of passengers, but also for conducting operation under exacting schedules, it was decided to install the most complete and effective signaling system procurable. The problem involved the prime consideration of:

Safety and reliability.

Greatest capacity of the lines consistent with the above.

Facility of operation under necessarily restricted yard and track conditions.

In order to obtain the above desiderata it was decided to install a complete automatic block signal system for the high-speed routes, block protection for all obscure points on the low-speed routes, and to operate all switches both for line movements and in yards by power from central points. This necessarily involved the interconnection of the block and switch movements at many locations and made the adoption of the most flexible and compact appliances essential.

Of the various signal systems in use it was found that the one promising entirely satisfactory results was the electro-pneumatic block and interlocking system, by which power in any quantity could be readily conducted in small pipes any distance and utilized in compact apparatus in the most restricted spaces. The movements could be made with the greatest promptness and certainty and interconnected for the most complicated situations for safety. Moreover, all essential details of the system had been worked out in years of practical operation on important trunk lines of railway, so that its reliability and efficiency were beyond question.

The application of such a system to the New York subway involved an elaboration of detail not before attempted upon a railway line of similar length, and the contract for its installation is believed to be the largest single order ever given to a signal manufacturing company.

In the application of an automatic block system to an electric railway where the rails are used for the return circuit of the propulsion current, it is necessary to modify the system as usually applied to a steam railway and introduce a track circuit control that will not be injuriously influenced by the propulsion current. This had been successfully accomplished for moderately heavy electric railway traffic in the Boston elevated installation, which was the first electric railway to adopt a complete automatic block signal system with track circuit control.

The New York subway operation, however, contemplated traffic of unprecedented density and consequent magnitude of the electric currents employed, and experience with existing track circuit control systems led to the conclusion that some modification in apparatus was essential to prevent occasional traffic delays.

The proposed operation contemplates a possible maximum of two tracks loaded with local trains at one minute intervals, and two tracks with eight car express trains at two minute intervals, the latter class of trains requiring at times as much as 2,000 horse power for each train in motion. It is readily seen, then, that combinations of trains in motion may at certain times occur which will throw enormous demands for power upon a given section of the road. The electricity conveying this power flows back through the track rails to the power station and in so doing is subject to a "drop" or loss in the rails which varies in amount according to the power demands. This causes disturbances in the signal-track circuit in proportion to the amount of "drop," and it was believed that under the extreme condition above mentioned the ordinary form of track circuit might prove unreliable and cause delay to traffic. A solution of the difficulty was suggested, consisting in the employment of a current in the signal track circuit which would have such characteristic differences from that used to propel the trains as would operate selectively upon an apparatus which would in turn control the signal. Alternating current supplied this want on account of its inductive properties, and was adopted, after a demonstration of its practicability under similar conditions elsewhere.



After a decision was reached as to the system to be employed, the arrangement of the block sections was considered from the standpoint of maximum safety and maximum traffic capacity, as it was realized that the rapidly increasing traffic of Greater New York would almost at once tax the capacity of the line to its utmost.

The usual method of installing automatic block signals in the United States is to provide home and distant signals with the block sections extending from home signal to home signal; that is, the block sections end at the home signals and do not overlap each other. This is also the arrangement of block sections where the telegraph block or controlled manual systems are in use. The English block systems, however, all employ overlaps. Without the overlap, a train in passing from one block section to the other will clear the home signals for the section in the rear, as soon as the rear of the train has passed the home signal of the block in which it is moving. It is thus possible for a train to stop within the block and within a few feet of this home signal. If, then, a following train should for any reason overrun this home signal, a collision would result. With the overlap system, however, a train may stop at any point in a block section and still have the home signal at a safe stopping distance in the rear of the train.

Conservative signaling is all in favor of the overlap, on account of the safety factor, in case the signal is accidentally overrun. Another consideration was the use of automatic train stops. These stops are placed at the home signals, and it is thus essential that a stopping distance should be afforded in advance of the home signal to provide for stopping the train to which the brake had been applied by the automatic stop.

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.



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.



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.



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.



[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.



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.



[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: