The daily morning journal and courier. [volume] (New Haven, Conn.) 1894-1907, 1901-01-18
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THIRD-RAIL CONSTRUCTION.
Details of the Electric System on the
Manhattan Elevated.


Details of the Electric System on thu
Manhattan Elevated.
Detailed and technical descriptions o.
the new electric power-house OF the
Manhattan railway, and other features
| of the electric equipment now in pro-
| gress, contributed by the officers hav-
| ing the installation in charge, appear
| in the January number of the Street
| Railway Journal w. r.. Baker, gene
| ral superintendent Of the Manhattan
railway describes the steam plant and
the third-rail system, and of the latter
says:
| THE thrd-rail system possesses a
number of important advantages over
| the overhead trolley wire construction,
1t provides conductor Of large current
carrying capacity, thereby greatly re-
| ducing required installation of feeder
| cables. The rail offers a large contact
| surface for transmitting current to
moving trains. The method of support
| ing the rail on substantial insulators
| placed on the track ties obviates use of
| unsightly and dangerous wires and side
| poles. The section Of the third rail
| used on the Manhattan railway is a
standard section of the Lackawanna
Iron and Steel company, weighing one
hundred pounds per yard, and is rolled
in sixty-foot lengths. In order to OBJ
tain a rail having greater conductivity,
an investigation was made of effect of
various compositions on the resistance
of steel and the conclusion was
reached that reduction in percentage
of carbon and manganese tended to in
crease conductivity. The composition
adopted, therefore. was as follows:
Carbon .073 per cent; manganese, ,341
per cent; sulphur, .073 per cent; and
phosphorus, .069 per cent The use of
the above composition results in rail
so soft as to be quite unfit for ordina-
ry railway service, but recent tests
show that the value of this rail as a
conductor has been largely increased.
The resistance measures about eight
times that of copper of equivalent Sec
ton, while similar tests on the ninety
pound traffic rail used by the company
show a resistance of from ten to twelve
times that of copper The third rail
has a cross-sectional area of 9.S square
inches and Is equivalent in conductive
ity to about 1850, 900 circ. mills of cop
per.
Where the length of the track be-
tween sub-stations does not exceed
sixty-ffve hundred feet, and with six
car trains running on a fifteen-mile-
per-hour schedule, at one minute head
way the third rail alone Is sufficient to
maintain, at the end of section, the
voltage to within about 10 per cent. of
the suh-station voltage under average
load conditions. The insulating block
and castings for the third rail are SIM
pie and inexpensive. The design of the
rail clips is such as to allow the rail en-
tire freedom to expand endwise. and a
sufficient clearance is provided to pre-
vent undue strain on the insulators,
which would otherwise result from de-
lection in the structure girders and
Jarflng of the ties. In order to provide
Tor expansion of the third rail, it is d.
Vlded into sections of five-rail lengths.
Or three hundred feet each. These
three hundred feet sections are securely
anchored a the center by sectional an
chor clips. Before leaving the mill, the
rails were provided with seven-eighth-