The daily Gate City and constitution-Democrat. (Keokuk, Iowa) 1916-1922, 1916-07-24
Railyay Age Gazette Clues
History of Construction
and Description of .Struc-
ture

The Railway Age Gazette of July
81, contains a very interesting article
on THE Reconstruction of the Keo-
kuk Bridge" This is Illustrated by
number Of excellent pictures Of the
bridge and diagrams Of construction.
The article follows:
The erection OF q new superstruc-
ture for the Keokuk and Hamilton
bridge over the Mississippi river at
Keokuk, Iowa, has just been complet-
ed, thereby replacing II old spans OF
cast and wrought iron which had car
ried railand highway traffic across the
river for more than As years. Con
siderable interest is attached to the
details OF the old structure and the
excellent condition of the material af-
ter its long period OF service. The
bridge carries miscellaneous traffic
consisting OF trains Of the Keokuk
branch of the Wabash, of the Toledo,
Peoria & Western, and OF an interur-
ban line, as we'll as highway traffic.
The steam road traffic consists Of
six trains each way daily and the in.
terurban business Of car each way
every hour
The bridge is located about one-half
mile south Of the dam and power plant
Of the Mississippi River Power COM
pany, and the government lock. The
bridge, exclusive of approaches, is
2.194 feet long and consists of 10 fixed
spans and a draw span. Commencing
at the east abutment there are eight
spans varying from 14s to 1862 feet
in length, followed by two spans OF
254h feet, with draw span adjacent
to the west abutment, having a total
length of $50 feet. The piers and
abutments are all founded on rock at
a minimum depth of SO feet below the
base of rail. All of the piers are on a
slight skew to the northeast.
Interesting Old Spans.
The old structure, built in 1869 and
1S70, and placed in service early in
1871. presented many features OF In
terest. The old spans were all Whip
pie trusses, having parallel chords
with the exception of the draw span.
the top chords OF which were Slight
ly bowed. The end and intermediate
posts were made uD of Carnegie oc-
tagonal columns, the top chords OF
two Ibeans. two channels and
cover plate, the bottom chords Of eye
bars, the diagonals and all latera1s Of
loop bars, and the top lateral struts
of tubular sections of cast iron. Cast
iron joints were provided at the panel
points to facilitate the connection OF
the members. There was almost a
total absence of splice plates or other
means of affording positive coDnsc-
dead load stresses being relied upon
to hold the structure together.
The bridge was a through struc-
ture, carrying all traffic on one deck.
the trusses being placed at 81 feet 6
inches, center to center, to afford an
adequate driveway, with g. single rail
road track in the center; sidewalk
was carried outside the trusses on
either side. The track and driveway
floor was carried on timber cross ties.
supported on two wooden stringers
under, each rail, with jack stringer
next to each truss. The floor beams,
of unusual design for this day, con-
sisted OF two 10-inch channels,
trussed by means of eye-bars and cast
iron posts. The old structure was
built and owned by the Keokuk &
Hamilton Bridge company and was
toll bridge, an arbitrary being i'm
posed on the steam road and interur-
ban traffic The new bridge is bling
financed by the same interests and
the existing traffic arrangements will
continue.
The New Bridge.
The new superstructure for the
eight shorter spans at the east end
of the bridge. consists OF parallel chord
riyeted Pratt trusses. The two 2541a-
foot spans are curved chord Pratt
trusses with riveted top chords and