The New York Subway

r 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 consideratio

lved the prime c

and rel

f the lines consist

er necessarily restricted

ll 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 i

ted 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 si

t before attempted upon a railway line of similar length, and the contract for its installat

sually 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 mode

nitude of the electric currents employed, and experience with existing track circuit control systems led

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

AL POST, SHOWING LIGHTS,

sidered from the standpoint of maximum safety and maximum traffic capacity, as it was realized that the rap

trolled 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

nsideration was the use of automatic train stops. These stops are placed at the home signals, and it is thus essential that a stopping distanc

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

T, SHOWING TRANSFORMER AND IN

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 diagramat

, SHOWING STOP TRIGG

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

5 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 b

IGGER ON TRUCK IN POSITION

rangement of signals is illustrated on pa

op 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 tr

he third home signal in the rear; this signal can be passed under caution, and this distance between t

ock 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

NTERLOCKING MACHINE

IGNAL CABIN SOUTH OF B

of Block Sig

ack 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 t

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

used. The signal lighting is supplied by a special alternating curr

ing 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 dang

iability of operation under the most adverse conditions, and to provide for accessibility to all the parts for conve

ient 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 s

icate. These batteries are located in the subway at the various interlocking towers, and are charged by motor generators, one of which is pla

14, 16, and 17. Three of these are reserve compressors. They are motor-driven by direct-current motors, taking current fr

R BLOCK AND INTERLOCKING SYSTEM

mined 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 spe

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 arra

er 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 de

ODS OF BLO

L SYSTEM ILLUSTRATING POSSIBLE POS

ocking

y 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 restric

through the medium of power-operated interlocking plants. These plants in the subway portions of the line are in all case

nts installed will be inte

n. Inte

nes.

ve

N L

Hall,

Stree

Stree

Stree

treet

treet

Stree

SIDE

Stre

Stree

Street

Street

an Viad

Street

Street

n Stre

Street

SIDE

Stre

Juncti

Stre

venue Y

chester Avenue

a Avenu

n Stre

Street

-

l, 3

als, both block and inte

signa

signal

t sign

al,

ber of sw

, 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