Evening star. [volume] (Washington, D.C.) 1854-1972, 1913-10-20
Railway Bridge Building.
By Frederic ]. Haskin.

The twenty-third annual convention OF
the American Railway Bridge Building
Association. which will meet In Montreal
tomorrow. has a peculiar interest because
Of its proximity to the famous Quebec
bridge now being reconstructed. The parts
of the new structure are being made at
the st. Lawrence Bridge Company plant
and a trip through this great establish
ment will be one of the features of the
convention. The newly completed 81
Lawrence bridge also will be inspected
with interest, because of number OF IN
novations introduced in its construction.
The progress I'm bridge building is quite
as notable as In other building operations.
The building of great bridge Is a much
more difficult task than the erection OF
zkyscraper building. Because the most
dtficuIt work Is now sometimes perform
"a under water, or the bridge is a little
m, of the freouented thoroughfares. the
,,uhitc IL not aware Of the enormous risk
and labor called forth In Its building.
The slightest deviation from the omen
sions or the smallest flaw in the materlai
used may cause the failure OF the struc
t1re. involving the loss OF miiilohs vi
dollars and much human life. when the
first Quebec bridge was about nai1 com-
Melted In 1907. II CO. apsed without warn
ing. Eighty persons were killed ano
vast amount OF money was lost.
The failure was due TO faulty materials:
7, was designed to sustain unit Welsht
OF 80 900 pounds and failed under stfees
Of less than LOO. In the erection OF the
new structure every possible precaution
rs taken to guard against repetition OF
the disaster. Every bit of materlal ls
subjected TO the most rigid tests, ana tne
EXPERT bridge builders of the continent
are eager to inspect the metnoas us
which this Is being done in the various
rarts of the structure. The trusses OF
fire new bridge are to be twice as strong
and the bottom cords i've times as stlouS
as the first bridge. This bridge IS TO De
located about eight miles from 0uo ,.",,
and will contain the argest single span
of any bridge yet built. the distance oe-
tween the two main piers being l,soo rect
II IL not so much for it's size, however
as for its design that the Quebec bridge
is r m arkable.
Quebec Bridge Several bridges
in the United
Not the Largest. States are larger
and have cost more to erect. Among
them is the Manhattan bridge in New
York city. recently opened for foot traf-
nc. This bridge is double-deck pate n
Its first deck will have thirty-five-foot
roadway in the center and two subway
tracks and an eleven-foot wide footwalk
upon each side. The top deck will have
four trolley tracks. The total width of
the Manhattan bridge is 40 feet The
land secured for it's building included
16O feet upon each water side, The land
upon the Manhattan side cost SS,OOO,OOO
IL was in the improved tenement district
and Ii was necessary to condemn many
buildings which were paying their own,
ers good profit. The b ooklyn land
was in a poorer district and only half as
valuable.
The development of railroad traffic has
had a great influence upon the methods
and requirements OF bridge construction.
Both cars and locomotives are being built
heavier than formerly In order that they
may ca ry greater loads. The stress upon
the railroad bridges has increased proper
tionally. Upon some roads all freight cars
are required to have a capacity OF 100 600
pounds. An important feature of railroad
bridge construction is strengthening
bridge or replacing II with new one
without interfering with traffic. Some
times this is done by substituting false
work under the bridge while new sup
ports are being built. Sometimes other
means are used. A bridge crossing the
Iowa river at Columbus Junction has
been one of the recent notable recon-
structions. Sometimes II becomes neces-
sary to have a double track in place Of a
single one. A bridge near Montreal has
recently been changed from q single to a
double track without interfering with the
trafi1c. Another track was built next to
the old one. The old bridge was then re-
moved span by span so carefully that
parts of IL could be used elsewhere. Then
a second new track was built onto the
first. thereby making q complete double
track idge.
The Improvement in metal manufactures
has given a greater tensile STRENGTH to
steel and made possible feats which
would not have been undertaken a few
years ago. While some concrete bridges
are being erected. steel is now the most
important bridge-building material. The
first metal bridges were of cast iron and
they came into use near the close of
the eighteenth century. The first of these
was over the Severn river in ENGLAND and
the most celebrated the Southwark
bridge, erected over the Thames river,
which was opened in 1924. Cast iron was
superseded by wrought iron in bridge
construction. The tubular bridges of the
type OF the Britannia bridge in England
and the Victoria bridge in Montreal are
the best examples of the wrought iron
Kind were built in the United States.
The iron girder bridge. the cantilever
bridge and the suspension bridge are the