The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1883-12-22
The Great Cantilever Bridge over
the Niagara River.

This double track railroad bridge, lust
completed, is located about 300 feet above
the old railroad suspension bridge. SPAN
ming chasm $40 feet wide between the
bluffs, and over 200 feet deep.
As the foaming rapids at this point rem
dered it impossible to build piers in the
river or erect temporary supports, it was
necessary to design structure which
could be erected without such false work
to attain this end a bridge Of the cantilever
type was adopted, which would be self
supporting during erection. The principle
of the cantilever is that of beam sup
ported at or near its centre, with arms ex-
tending both ways, one arm being held
down by an anchorage or counterweight,
SO that the load on the overhanging arm
produces an uplifting force in the opposite
end which is resisted by the counterweight
The designs of this structure were worked
out Jointly by G. c. Schneider, chief engi-
neer in charge of the work, and Edmund
Hayes, engineer of the Central Bridge
Works
The structure consists of two immense
steeltowers, 132 feet 81 inches high, resting
on stone piers 80 feet high Each of these
towers supports caniileyer 395 feet 5-16
inches long. One end of each tower rests
upon an abutment at the edge of the bluff,
while the other end extends out over the
river. The shore ends of the cantilevers
are anchored to the abutment masonry or
anchorage piers, and both river arms are
connected by an intermediate span of 100
feet, which is suspended from the extreme
ends of the river arms The total length
of the bridge proper is 910 feet 4 { inches
between the centres of theanchorage piers
the clear span between towers being 470
feet. The height from surface of water to
base of rail is 239 feet.
The towers are braced steel structures,
containing four columns each, which are
made up of plates and angles riveted to-
gether, braced with horizontal struts and
tic rods. The batter of the columns at
right angles to the centre line of the bridge
is | in s. and parallel to the centre line l
in "a.
The trusses are two in number, % feet
apart between centres; the various mem
bers being connected with steel pins Z J
inches, 81 inches, and 81 inches in dame
ter, turned accurately so as to fit the bored
pin holes within 1-64 of an inch. The
depth of the cantilever trusses over the
towers is sc feet, and at the shore ends 21
feet, and at the river ends 26 feet. The
lower chords and centre posts are made Of
plates and angles riveted together and
latticed, the intermediate posts being of
u by 15-inch channels, latticed The upper
chords of the cantileyers are S-inch eye
bars, the shore arm having compression
member Is inches deep, composed Of plates
and angles packed between the chord bars.
The shore ends of the cantilevers are at
tached to short links, oscillating on pins
anchored to the abutment masonry, which
serve as anchorages and also as rockers to
allow for expansion and contraction of the
shore arms produced by changes of tenn
perature. Expansion joints are also pro-
vided for at the connection Of the inter
mediate span with the river ends of the
two cantilevers,
The material used in the superstructure
is steel and wrought iron Towers and
heavy compression members, such as lower
chords and centre posts, are of steel, as are
all pins All tension members are of
double refined wrought iron. The only
use made of cast iron is in the pedestals on
the masonry and in filling rings; the cast
ings at the top of the towers are all steel.
All materials were carefully inspected at
the mills, and none was allowed to go into
the structure without being properly tested
and found to possess the strength, elasti-
city, etc, called for by the specifications.
Scientific Ame1icdn.