Polk County observer. (Monmouth, Polk County, Or.) 1888-1927, 1915-10-22
EXAMINES THE BRIDGE
EXPERT DECLARES STRUCTURE
OVER WILLAMETTE UNSAFE.
Prohibition of Vehicles Such As Now
Make Daily Use Of Bridge Rec
ommended By Holmes.

Willamette river at Salem is unsafe
to travel and traffic thereon should be
prohibited, according to a report OF
Howard W. Holmes, assistant state
engineer, and bridge expert. The
structure has outlived all practical
usefulness, and should be condemned
without further delay, says the en-
gineer after having made an exhaus-
tive examination of it's physical con-
dition. The principal feature of the
report refers to the deterioration of
the metal at the connections, which
has deprecated so that the bridge is
in danger when carrying heavy loads.
With the report of the engineer it
looks as though Polk and Marion
counties would be compelled to join
in the construction of the proposed
new bridge, the estimated cost OF
which is around $250,000, although
Polk is desirous of evading any un-
necessary expense, which would be IN
cluded in the Forthcoming budget. The
report of the engineer in detail is as
follows:
Top Cords-These members are
built up of plates and angles with
double lacing on the lower side. Con-
siderable deterioration has taken place
throughout these members, particular
ly at the connections, where rust pits
greater than one-sixteenth inch in
depth were noted. Water has also
percolated between the splice plates,
which, originally, had not been
brought to proper bearing fit, caus-
ing rust and scale which now is full
ly one-eighth inch in depth. Between
connecting points, the metal is in a
fair state of preservation, particular
ly considering the apparent lack OF
maintenance during the early life of
the structure. Generally the reduc-
tion of sectional area is not over
5 per cent of the original section.
At the connections, however, the re-
duction in area of effective metal may
be considered as high as 10 per cent.
A few cases were noted where the
metal had deteriorated to the extent
of 20 per cent of the original area.
The principal weakness in the top
chords is that caused by excessive sag
or bending at the third and fifth pan
ell points from each shoe, this de-
Election varying from one to two inch
es. A detection from one-fourth to
three-fourths was also noted at mid
section and directly over the sub
posts. This bending is accompanied
by slight DETECTION in the subver-
teal located directly above the star
connections. The bending above re-
ferred to could be slightly remedied
by the adjustable counters, but as the
trouble is caused primarily by exces-
sive loading which, undoubtedly, has
caused severe stress in the extreme
outer fibers Of the metal, the ADJUST
ment mentioned would afford only un-
certain and temporary relief, with
reference to the top chords, under
regular traffic conditions.
Bottom Chords and Web-Members.
The bottom chords and web-mem-
bers in both spans are fairly well pre-
served excepting in the immediate Vi
cinity of the connections, where rust
pits and a general reduction of about
Is per cent in the original effective
area of metal was observed. All in
termediate and end posts were found
to be badly rusted below the floor
level. Five of the main end posts and
the plates connecting them to the
shoe. as well as the shoes themselves,
show large reduction in area of met
al due to excessive rust.
Sub-posts which tend to support
and maintain the top chord in line
show considerable DETECTION and
clearly indicate that they are carry
ing greater loads than that for which
they were originally designed. As an
indication of the deteriorated eondi-
tion of the end posts and other mem
bers above mentioned, it may be of
interest to state that in determining
the depth of rust and scale on the
main end posts a wire nail was inad-
verteutly driven, without effort,
through the metal with the aid of a
common clawhammer.
Laterals and Wind Bracing.-The
top lateral system WIS lOuuu W W
in good condition and well adjusted.
although they offer only small resist
ance. extending as they do, over two
panel lengths. All wind bracing mem
bers are in fair condition. excepting
at their connections, which latter
show a marked depreciation in origi-
nal strength.
The bottom lateral system is en-
tirely out of adjustment and the con-
Meeting plates at the shoes are almost
rusted away. 1t was found that the
lateral connections at the end of floor
beams in both spans are held in posi-
tion bv an Sxs inch timber on top of
the floor beam. As this timber is
shorter than the length required. the
connections have shifted toward the
center Of the bridge, resulting IN a
sag Of from three to four inches at
the center of the lateral rods in ques-
ton
Approaehes-Tbe timber trestle aP-