Evening times-Republican. [volume] (Marshalltown, Iowa) 1890-1923, 1899-09-06
THE Mo1NGoNA BRIDGE.

ClIlZ6u can SHRINK. 81
THE MOINGONA BRIDGE.
The Chicago & Northwestern railroad
has received considerable publicity on
account of the Improvements that it
has under way on it's Iowa lines, but
none of it's undertakings has attracted
the attention or is of as much interest
as the bridging of the Des Moines river
few miles west of Boone. At this point
the river runs between very high and
precipitous bluffs, which were consd-
cred mbassable obstacles when the
road was first built. 1t is now the inten-
ton of the road to straighten its line
the river as though nothing We're there
to prevent. The undertaking is a stu
pendous one, a description of which will
be of interest to most readers.
The type of the bridge is that com
monty known as the steel trestle, which
consists of a series of steel bents rest
ing on masonry piers, and supporting
steel girders at the top. These Orders
are forty-f1ye feet and seventy-five feet
long, alternately, SO that each bent
supports one end of a forty-tive foot
and one end of a seventy-five foot
girder. The two bents under each
forty five foot girder are rigidly braced
together forming tower There is
bracing between the two bents support
ing the seyenty-tive foot girders also.
1 a side view of the bridge will there
fore present the appearance of a sue
cession of towers with a seventy-five
foot girder spanning from one to the
other. Each of the bents spoken of
consists of two steel posts leaning to-
wards each other and braced together.
They are about nineteen feet apart at
the top and spread to an extreme width
of about seventy feet at the bottom.
There are forty-one of these bents in
all. Across the channel of the river
there is a truss span of 800 feet long
which also rests on steel towers, but of
different construction from those sup
porting the girder spans. The extreme
length of the bridge is 2,6S5 feet and
the greatest height is 1855 feet above
the water 1t will carry two tracks,
thirteen feet between centers, and is de-
signed to carry the heaviest modern en-
gines and loads. There are number of
steel trestles in the world, higher than
this one, and several in the United
States that are higher, but they are all
built for single track and are generally
lighter in construction. 1t is believed
that this Will be the highest double
track steel trestle in existence.
| The foundations preSAnf one of
the most interesting engineering
problems, and great amount
Iof preliminary investigation has
been made to determine the
nature of the material underlying the
river bed. Two gasoline engine drills
have been kept running for five months
and about seventy holes varying from
! fifty to $50 feet deep have been drilled
down into the underlying material and
samples of the same brought to the
Surface for examination and the thick
! ness of each stratum noted.
The structure is being built for all
time and every possible means is being
taken to make it permanent. 1t has
been computed to take about 5000 tons
iteresting features of this work are two
:
| five feet in depth and about 800 feet
4 from grade to grade, which are to be
filed To do this temporary trestle
which the dirt is dumped to make the
entertainments. There are two trestles
at each of these canons eighty feet
apart and parallel 10 each other. Each
/ trestle carries double track upon
a.
ldra wn by horses and the dirt is dumped
on movable aprons by which the dirt is
spread over the bases of the hills
These aprons spread the dirt to a Width
of about ITO feet but as the extreme
4 width of the hills at the bases is about
go feet there is still about sixty feel
lon each side which is spread by scrap
lers. These trestles will be buried il
the I'LL. There is one cut in the line
forty feet deep. another thirty-two feet
a besides some smaller ones, necessitatlni
the removal in ali of about 500 0oi
yards Of earth. The whole length OF
4 the new line is seven and a half miles
and will shorten the length of the roaC
Iabout three miles. A temporary bridge
is being built across the river on piline
to convey material across for that par
ioI unt DflGSe. ltniS material ana tina
A for the temporary bridge is run dowr
an inclined plane about 100 feet at al
angle of about forty-tive degrees in car
ATTACHED to a shaft, the loaded car i,
descending draws the empty one up
The material of the foundation is aimee
to be of the best quality. The stone i!
4. from the Mankato quarries and tn,
strength of the cement is tested by ma
chinery.
The engineer in charge of the work
from whom this Information has beer
gained is Mr.. w. c. Armstrong, son o
j. G. Armstrong, an old resident o
Marshall county. He was born ant
raised in Marshall county, educated a
, the Agricultural College at Anles in tn,
class of 81 in the class of civil engi
neers and has spent the greater portion
of his time since in railroad work
IOWA PRESS COMMENT.
The Council Bluffs Nonpareil believe
that those who are giving comfor
and aid to Aguinaldo and encouragin
} him to prolong the contest are not onl
disloyal but they are inhuman. Aguin
aldo has among his followers not NOR