The Idaho Republican. [volume] (Blackfoot, Idaho) 1904-1932, 1913-07-04
which to span rivers.

pec.flcatio;.s and figures, su?h as
is necessary 10 be assured II good
bridge work. Granted that they are
trying to be honest and not unduly
influenced by private interests, there
is too often tendency by the county
commissioners to accept a bid and
take the bridge that is built just as
it comes, hoping that it is good job.
The most important thing at first is
to have the bridge properly designed.
When bids are opened for a certain
bridge a dozen manufacturers will
submit a dozen designs, all at diff
ferent prices, and the layman can
scarcely be expected to know the diff
ference in their quality. The engin-
Ger of the bridge company knows
that the chances are in favor of the
lowest bidder, whose design appears
to be all right, and knowing this he
will take advantage of every point
possible to cut down on the cost of
building it, The novoice who is not
able to see into the various points in
design is very likely to lose in deal
with steel bridge manufacturers. If
the contract is let by schedule, so
that whatever amount of steel is nee
essary is to be paid for, the bridges
will be loaded down with as much
metal as can be fastened on, not in
creasing its strength, but making
more profit on the steel. On the
other hand, if a lump sum is allotted,
every possible detail will be left out.
Bridge designing is a special and in
tricate science, and the service of an
expert will soon pay in proper de-
sign and and understanding of the
necessary conditions.
A relief comes in several states
thru the work of the highway COM
missioner. A force of bridge engin-
GERS as large as can be supported by
their allowance is kept busy inspect
ing bridge designs or making new
ores for various counties in the state
Perhaps the best results have been
obtained where the custom was put
| up to the commission 1T first, and
| their design handed to the contract
or as a standard on which to base his
prices. Then, having given each con
tractor the specifications to fulfill
there is square deal all around and
the contract letting becomes safe. All
that remains is to see that he speci-
ficaions are fulfilled.
One of the most wasteful things
that parades in the guise of economy
is the tendancy to cut costs by skimp-
ing on material. Concrete work
lacking sufficient and proper ingred.
tents, or not thoroughly mixed, is
wholly unreliable and liable to go to
pieces any time. Dirty sand, which
to outward appearances makes as
good job as any other, gives no
strength to the concrete. 1t is de-
cidedly worth while either to wash it
very thoroughly to remove the mud,
or to haul good materials from else
where. The proportion of cement al
so is vitality important. Specifica-
lions furnished, cover this point, and
the township or county authorities in
charge should see to it that they are
strictly adhered to. A barrel of &C.
ment left out now and then will not
show until the emergency comes and
will make neat difference in the
builders profits. A reliable inspect
or should be on the job to see that it
is put in. The honest contractor
will be glad to have an inspector
there to see how we'll the work is
done.
There is also a great tendency to
cut down on the width of small bridg
es. For ordinary wagon traffic, a
narrow bridge is sufficient, particu-
larly if the side walls are built up
for safety. 1t is we'll to remember,
however, in putting up structure
that is to last perhaps 200 years,
that there may be other forms of i'm
plements and machinery to 60 over
it. The massive tractor of today and
the motor truck that carries a small
carload may only be fore-runners of
future types. 1t is safer for the fut-
ure and more comfortable for the
present to build a 16-foot roadway,
except on remote side roads, where
travel is light. Another weak spot
that has wrecked many bridge is
poor foundation work. The base
should be carried down we'll below
the channel level, or, if possible, to
solid rock.
Solid concrete is not the only kind
of bridge that may be permanent and
dependable. A steel bridge, we'll de-
-