Omaha daily bee., 1883-06-26
THE NEW NIAGARA BRIDGE.
A Novel Principle in It's C~onstruc'
tion-To be Done in Eight
Months.

Aotonto pioDc'
The Canada Southern railway bridge
over Niagara river is to be built at a
point about 300 feet above the present
suspension bridge. The contractors have
engaged, under a heavy penalty, to com
plete the whole work by LIST December
next, about eight months from the time of
beginning operations. The time occu-
pied in building the suspension bridge
was three years. A comparison will give
an idea of the vast progress made in re.
cent years in the art of bridge building.
The new structure will embody a new
principle never before illustrated by any
large work actually finished. Two SINH
lar bridges, however, are now being
contradictions the new Tay bridge
over the Firth of Forth, Scot
land, and the second for the
Canadian Pacific railway over the Fraser
River, British Columbia. Bridges built
after the new design are known MS canti-
lever bridges. Each end is made UP of q
section extending from the shore nearly
halfway over the chasm. Each section
is supported about its centre by q strong
tower. The outer arm having no sup
port, and being subject like the other to
the weight of trains, a counter-advantage
is given by the shore arm being anchored
or weighted.
This style of bridge has been adopted
so rs to avoid the very great expense in
volved in the construction of a suspension
bridge. The towers on either side will
rise from the waters edge. Between
them will be n clear span of 500 feet over
the river, the longest double-track truss
span in the world. The shore arm of
each cantilever having been built and an
chored, the other arm will be constructed
in sections of % feet, the whole being
made self-sustaining as each section is
added. The ends of the cantilevers
will reach only 1916 feet beyond
the towers, leaving a gap of 1876 feet
to be filled. The link will be supplied
by an ordinary truss bridge, which will
be swung into place and rested on the
ends of the cantilevers. Here provision
will be made for expansion and c~ontrac.
ton by allowing play between the ends
of the truss bridge and of the cantiley.
ers. AT the same time the bridge will
be thoroughly braced soas toprevent dan
ger from the lateral pressure of the wind.
Inc wave mOtlOn pereeptlble on q
suspension bridge will not be felt on the
new structure. The total length of the
bridge will be 800 feet. 1t win have q
double track and win be strokg enough t,
bear two Of the heaviest freight trains OK
tending the entire length of the structure
and under a side pressure of wind a
seventy-fve miles per hour, and aver
then it is to be strained to only one-fftl
of its ultimate strength.
The towers will not rest on bed rock
as the rush of the river would sweey
away any caissins or other works in.
tended to be used for excavations but the
foundations will be in the large boulderl
that have dropped from the cliff during
the past ages, the crevices being flleG
in white cement, making a solid founda.
ton. The pressure will be so divided
that upon the foundation rocks it will b,
only 20 pounds per square inch. Tn,
top of the stone structures will be 90 fee
above the water level and from these the
steel towers supporting the cantilever,
will rise 100 feet. From the tower
foundations up the whole bridge will b,
of steel, every inch of which will be sub
ject to the most rigid tests from the time
it leaves the ore to the time it enters tn,
structura