The Indianapolis journal. [volume] (Indianapolis [Ind.]) 1867-1904, 1903-01-18
TRAIN SIGNAL SYSTEM
BRANCH OF RAILROAD OPERATION
LITTLE KNOWN 70 PUBLIC.
Method Taught by a Miniature Train
ut Massachusetts Institute Of
Technology.

BOSTON, Jan. 16.-In one Of the labora-
| tories of the Massachusetts, Institute of
| Technology there is little train of cars,
running along a little railroad. When the
| little train is set in motion it automatically
| opens and closes number of electric cir
cults connected with a series of railroad
| signals, and person following its course
sees in miniature exact reproduction of
a regular train. passing from one city to
another and automatically signaling its
] position on the track to any other train
that may be following behind it.
| This miniature railroad at first glance
suggesting a toyshop in Christmas time, is
| part Of a regular course in the signaling
! given for the benefit of the institutes stu
dents of railroad and electrical engineering,
covering department of railroad operation
! of supreme Importance to the safety of
travellers but very little known by those
| who are thus safeguarded. The actual sig
nails. as they string along beside the tracks,
| are, of course, nearly as familiar the
telegraph poles that separate them, and
the presence of a signal tower, perched in
the air at every important terminal is
much a matter of course as the station
clock. What goes on in the signal tower,
1
ments of every car locomotive that
tiers or leaves the station, are among the
familiar mysteries of every DAY existence,
| and the little railroad in the institute lab
oratory is an object lesson for initiating
future railroad operators. builders and
perts into the very complicated secrets of
| their profession.
Railroad signaling is a department of
! comparatively small number of men are
| directly concerned but with which a much
larger number have to be definitely &C
quainted. The young American who is pre-
pairing himself for the profession of railroad
engineering, the engineering that plans and
erects great railroad systems, bridges rivers,
tunnels mountains and lays out terminal
stations with all their bewildering multi
plicity of tracks, may never have to stand
in the signal tower and actually direct the
movements of the trains. But every big
station must have it's signal system, manu-
featured especially to solve the problems
connected with the running of its own
trains. and it is the railroad signal engineer
upon whom devolves the duty of selecting
this mechanism, not only deciding the ex-
penditure of thousands of dollars for sim
gle piece of apparatus but assuming indi-
rectly the responsibility for the safety of the
persons whom the apparatus is designed to
protect. The engineer, again, may be called
upon to repair, or even to manufacture for
temporary service signaling system neces-
STATED by some piece of work upon which
he is engaged, often many days journey
from any regular manufacturer. His knowl-
edge must be even more exact, and very
much more comprehensive, than that of the
man who lives in the signal house and oper-
ates the levers of a single system with
which he is perfectly familiar
BASIS OF THE SYSTEM.
The student of railroad signaling be-
gins with the automatic signals which
any given train operates for itself. Every
railroad system is divided into blocks or
sections, varying in length from a quarter
of a mile, in the neighborhood of a big
city where trains are frequent, to 10 miles
or more in outlying places where trains are
few and widely separated. No two trains
are permitted on any one block at the
same time. The purpose of the signals.
of which there several varites all
working on the same general principle is
to keep each train informed to the con-
dition of the block ahead of it, Anybody
wooden arm that rises as If by magic when
a train has just passed-has noticed that
the does not fall until some little time
after the train Is we'll out of sight When
the falls the train is not only out of
sight but has left the particular block of
which the semaphore is the guardian, so
that the in the cab of an approaching
locomotive knows that his train can enter
without danger of collision.
The semaphore is worked by the train
itself. AS it passes over the track it
breaks an electric circuit at one end of
the block and connects ii again at the
other. When the circuit is broken the hid
den mechanism connected with the sema-
phore releases the arm, which rises by the
force Of gravity and remains at right angles
to the post until the train passes out of
the block and the mechanism again forces
the arm to the position of safety. But if
this mechanism gets out of order the signal
Immediately sets itself at danger and no
train is allowed to enter except by special
orders and with additional precautions
Near a large city station the blocks are
shortest to allow the passage of trains
close together; far away from the city they
increase in length until on some of the
Canadian and far Western railroads they
are as far apart as the railroad stations.
In some cases these signals are so ar
ranged that they cannot be disregarded
even If locomotive engineer should be
willing to take chances. When, for ex-
ample, such disregard OF signal might
precipitate an approaching train into an
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