Daily tobacco leaf-chronicle. (Clarksville, Tenn.) 1890-1895, 1890-11-06
MoaDeafuL tnaInsfaIna frAr.


afff' N"Nfff ~NNtfffN+f NNtN
Floating she Ohio Connecting Railway
Channel span.
The ta9Ineering and Building Record
gives M interesting account Of tbs work
81 floating the shannel span Of the Ohio
Connecting railway bridge near Pitts
burg Pa., and depositing it IN Ito rest
ing place ON the piers. The Ohio Con-
Meeting railway. about 1900 feet long,
"a essentially belt road. built chiefly as
q transfer between north and North
western and south and southwestern
roads NJ Piltsburg, and includes bridge
4,5J9 feet long across the upper part Of
Brnnots Island and the Ohio river. a
little below Pittsburg.
The channel span Of this bridge is a
steel single track through single inter
section span, with intermediate sub
panels and members. The trusses are
30 feet apart. and have maximum
depth Of 60 feet. They are 523 feet long
and have curved top chords TIN ma
sonry piers arc about 80 feet high, and
between Thorn an enormous river traffic
Of steamboats,. barges and RATS constant
" passes.
To avoid obstructing this traffic, as
well as 10 be somewhat less exposed to
danger from food, II was decided not to
build any false work, trestles or piling
whatever between the piers, but instead
TO assemble the span at the required lev
81, with It's axis perpendicular to the
final position, and far enough removed to
be clear Of tho main waterway, then TO
float II TO its required position and Sc
cure 1t 10 the abutmeut seats IN the
shallow water along the shore of the
island piles were driven on which to
erect tho false work and span.
The piles were arranged in rows cor
responding to tho panel of the bridge.
Each row was cut off and capped about
49, feet above normal water level, and
several lines of 90 inch steel beams were
laid across the caps. These formed
stringers on which timber trestle bents
Of suitable dimensions were erected, and
secured by wooden bracings and special
adjustable iron tic rods. On this false
work the iron and steel bridge members
were hoisted, assembled and connected
in the usual manner from n travelling
wooden erecting tower nearly 100 feet
high. This part Of the work was rapid
ly executed in fifteen working days,
Nine specially constructed barges were
then hoated into position under the 90
inch steel beams and between the rows
Of piles.
Tho barges were 1870 by 95 by feet
deep, strengthened by longitudinal and
transverse bulkheads, and contained in
lot valves through the bottom OF every
chamber. These valves were then closed,
and the water was pumped out in about
five hours by steam pumps ON three ada
cent tug boats, and rs the barges rose
they finally received the entire weight of
the bridge span and supporting false
work and floated it clear above the piles.
The false work was securely connected
together by longitudinal timbers and
temporarily bolted with iron plates to
the piles. Deoked barges We're secured
to the others and TO the false work at
tho ends, and carried four multiple
spoiled hosting engines, besides which
two others were set up on the shore, all
OF them being supplied with about 1000
feet Of lines.
The span was secured against over
turning by heavy steel guy ropes from
each end Of each barge. and guy ropes
were attached to the floating mass, the
barges disconnected from the piles, and
the hosting engines, winding upon
tackles made fast TO the shore, slowly
drew the barges clear Of the piles
Stringors across the rear Of the barges
and extra braces were then placed
where the piles had previously inter
fered, and the barges and their burden
again drawn forward, swung through
an angle of about 90 degs., and drawn
upstream between tho bridge piers,
which had about twenty-five feet clear
ance from the end barges
The movement was very slow, occupy
ing several hours, and was always in
very short stages, preceded by careful
adjustment of the guy lines. The bridge
was thus brought approximately to po-
sition twenty-one inches above the re-
quircd level Guide bolts were passed
directly through the shoes and inserted
in holes prepared in the masonry, and
the valves in the barges being opened
the false work gradually sunk until it
deposited the span safely ON its seats and
left it there free and clear. The total
weight moved by the barges was about
| 800 tons, 9ij of which was the weight
Of the permanent span. The false work
was removed and used TO erect, in its re-
luired position, another span of the
same bridge.