The Palatka news and advertiser. [volume] (Palatka, Fla.) 1908-19??, 1915-03-05

cost of steel or iron.
The first cost alone should not gov
ern in selecting bridge but rather
structure should be adopted that
| is long-lived, durable and of low
maintenance cost, for justice to fu-
ture generations demands that they
should not be burdened with excess
sive bridge levies. 1t is, therefore,
the more reasonable procedure to Sc
lect such a type that the cost per
year for each year of the life OF the
structure will be a small as possible,
so that inspection, depreciation and
sinking fund, painting and interest on
first cost may all serve as guides in
arriving at a final conclusion
Reinforced concrete bridges can be
designed to withstand the actions of
swift currents, providing care has
been taken in the design to avoid the
possibility of scour, and to keep the
pressure on the soil within allowable
limits. Of all the bridges built across
the Great Miami River, at Dayton,
Ohio. the ones which withstood the
action of the tremendous floods dur
ing the spring of 1913 were con-
structed of concrete, and the ones
which were washed away were of
steel. The only failures in the con-
crete structures were due to the rail
ings giving way, caused by driftwood
and houses that were swept over
them.
In Sandusky, Ohio, one concrete
bridge was buried under IS feet of
swiftly moving water. The only
damage sustained was few feet of
ratings carried away and these were
repaired for a few hundred dollars.
Comparative estimates were made
on the Vermillion Bridge at Wake
man. Ohio. The concrete arch was
estimated at--------------S $4,000
A steel bridge would costs 14,S00
The life of the steel bridge would
have been about 25 years, at the most;
the concrete bridge will last for gen.
erations.
Countless communities have now
turned to reinforced concrete for gen.
.eral bridge construction among
which may be mentioned the Kings
Highway Viaduct in st. Louis, 1857
fit. long and 90 #. wide, erected at a
cost of 100000; the Sandy Hill
Bridge across the Hudson, 984 #.
long and 35 #. wide, made up of
spans of 60 it.; this bridge was faced
with concrete blocks and the total
cost was $4,000; the Dallas, Texas,
Viaduct. 5105 ft. long, erected at
cost of S575000 and the magnificent
Connecticut Avenue Bridge in Wash
81 +Ot Of
100000.
The cities OF Pittsburg and Phila-
delphia have now turned TO the use
of concrete for structures of great
magnitude rivaling the most magni-
ficent ones of the Old World.
There is still another feature of
the selection of a type of bridge
which is of prime importance to a
community that is considering this
problem, and that is whether or not
the materials can be supplied by local
dealers, and whether the labor can,
to a large extent, be furnished by
the men of the community. In the
case of the steel bridge, the skilled
labor comes from out of town, the
steel is supplied from Pittsburg, or
Birmingham and the false work is
fabricated, in most instances, at a
distance from the job. With con-
crete bridge the gravel, sand, broken
stone, cement, lumber, teams, and help
usually come from local sources.
The comparisons between the two
types of structures may be aptly
summarized;
When built the steel bridge is un-
slightly, costly to maintain in road
way and painting, constantly in need
of inspection, and there is danger Of
rusting; it is also noisy and unsteady
under traffic.
1t is in general used only because,
up to the introduction of the plain and
reinforced concrete structures, it was
tire only fairly durable, low-priced
bridge.
The reinforced concrete bridge
when built is the most graceful bridge
made; there is no maintenance eX-
pense; little inspection is necessary;
lit grows stronger with age; is free
from vibration and it is quiet under
traffic.
HILL nFFn