Burlington weekly free press. [volume] (Burlington, Vt.) 1866-1928, 1883-07-06
The New niagara Bridge.

The Canada Southern Railroad bridge
over Niagara River is to be built at a
point about three hundred feet above the
present suspension bridge. The contractors
have engaged under a very heavy penalty to
complete the whole by the lst of December
next, about eight months from the time of
beginning operations. The time occupied in
building the suspension bridge was three
years. A comparison will give an idea of the
vast progress made in recent years in the
art of bridge building. The new struc-
ture will employ new principle
never before illustrated by any
arge work actually finished. Two SIM
liar bridges, however are now being con-
structcd-one, the new Tay bridge over the
Firth Of Forth, Scotland, aud the second for
The Canadian Pacific Railway over the Fraser
River, British Columbia Bridges after the
new design are known as cantilevcr bridges
Each end is made Of Il section extending from
the shore nearly half way over the chasn.
Each section is supported about its centre by
strong tower. The outer arm, having NJ
support, AN! being subject like thp other 10
the weight Of trains, II counter advantage
is given by the shore arm being anchored
or weighted.
This style Of bridge has been al opted so as
to avoid the very great expense involved in
The construction of the suspension bridge. The
towers on either side will rise from the VIA
ter's edge. Between then will b. n clear
span of tive hundred feel over the river, the
longest doube-lrack truss span in the world.
The shore arm Of each Canlilcvcr having been
built and anchored, the other arm will be
CONSTRUCTED in sections If twenty five feet
the whole beipg made sel-sustaiuiug as each
section is added. The ends of the cautIlevcrs
will reach only 80 feet beyond the towers,
leaving gap Of 12j feet t. he filed. The
link will be supplied 10y an ordinary truss
bridge, which will be swung into place aud
rested on the end of the canlicvtrs. Here
provision will he made tor expansion and
contraction by allowing play between the
ends of the truss bridge and of the cantlevcrs
At the same time the miidge will be thorough
y braced so as to prevent danger from the
lateral pressure of the wind, The wave"
motion perceptible on Il Supeusion bridge
will not be felt on the new structure. Tie
total length OF the bridge will b. S0j feet. 1t
will have double track and will be strong
enough to bear two of the heaviest ireig ut
trains extending the entire length OF the
structure, and under side pressure OF wind
at seventy five miles per hour, aud even then
it is TO be strained to only One-iifth Of its
ultimate strength.
The towers will not rest on bedrock, as
the rush of the river would sweep away any
cassons or other works intended to be used
for excavations, but the foundations will b.
in the large boulders that have dropped from
the cliff during the past ages, the crcvices
being filled in with cement, making II solid
foundation. The pressure will be 50 divided
that upon the foundation rocks it will be only
twenty five pounds per square inch. The TOP
Of the stone structures will be fifty feet above
the water level, and from these the steel tow.
ers supporting the canlleycrs will rise 1870
feet. From the tower foundations up, the
whole bridge will be of steel, every inch of
which will be sub ject 10 the most rigid tests
from the time it leaves the ore to the time ii
enters the structure.