New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1875-06-26
GOVERNMENT BRIDGE BUILDING.

WASHINGTON, June 24.-ln June, 1874, Con-
gress passed oh act authorizing and directing the COZ
strucon under the supervision Of the Secretary OF war;
OF substantial iron and masonry bridge across the Ana
costa or eastern branch of the Potomac River near the
NavyYard in Washington and appropriated for the pus
pose ST. 600 The bridge Ia nearly copleted ana
having heard from experienced engineers that the WORK
had been planned OF performed In manner crcotS
BILE to the Judgment skin Of the officers VINO nave
charge of IT, I took with me, recently, an expert
epced practical engineer who has given much time
and study to the subject OF brdgebuildng and tho laws
governing tho strength of materials, and visited tho
work.
From the advertisements inviting bids for the WORK
the following description OF the structure Is obtained
The bridge consist OF ~ Of 102 feet each ana
one draw Of So feet making the entire length 12oo fee@
Tho abutments and piers TO be founded on piles
from IL inches 10 inches In diameter placed three fees
from center to center and driven to refusal uouer NAM
mer weighing 800 pounds The tops OF the piles were
TO be cut of at bottom Of the river so az TO form Level
foundations for the masonry to rest upon The super
structure was composed OF two iron trusses 10 ices
in hight iron beams and wooden floors. The width OF
roadway to be 20 feet between the usses ana
the sidewalks be five feet wide on the outside OF
the rsses All parts OF the bridge were TO be 80 pro-
poroned that tho maximum strain resulting from 10
own weight and an applied load Of 100 pounds to the
,auore foot OF floor surface should exceed onesxth
of the ultimate rength or the iron. The drawspan was
to be what technically known 40 high-draw -thss
s one that raised and not turned to allow vessels To
pass through.
Our Investigations first directed TO defects in the
plan of the work The first defect TO be noticed is thAt
the bridge ia altogether low. The ground on both
sdes OF the river higher than the floor OF tho
structure, that the only extra expense that would
have been incurred by placing it 10 or IL feet higher
would have been In building higher piers and In con-
structing embankmcnt for the approaches. As the
bridge has built it Is the water that even
-boa or n under IL without the
draw being raised. Again, the door Of the bridge "a
stands Ia but little II any above the level OF tho
RIVER In times of high food The Washington end OF the
new bridge only 18 inches higher has the correspond
ing part of the old one. aud assured by persons
familiar with the river at this point that the water has
flowed end OF the old structure The roadway
Of the have been 10 or 10 feet wider Inc
present width 80 feet leaves spare room after 40
commodang the ordinary traffic between Washington
and Unontown But 1t Ia proposed TO extend tho trsks
Of one Of the railroads across this bridge WHOM
will leave the passageway either side Of y very mar
row.
find difference of opinion In regard 70 tho width o.
tho draw The depth OF water In the channel at this
point feet and the bridge is situated very near one
OF the most complete in the country and only
two miles from the Arsenal. AT the time the East
ern Branch has filed up rapidly within the past 50
years that while Bladensburs once had considerable
commerce. IL impossible for vessel OF any kind
to go there But IL SO feet Is sufficient width for draw
that point 1t certainly ought to have been built No
narrower while the truth Is that the opening
tanned by .ual measurement lie only 80 feet. The
form or the draw and It's construction are exceedingly
and awkward, and would not be credtabe 10 the
skill Of ordinary mechanic any time within the last 50
years. But defective the general plan OF the bridge H.
the execution OF it has many respects been even
In the first place tho foundations have properly
constructed The bed Of the river at the point where
| OF mud; but how deep it is nobody knows, as
soundngs appear to have been made For this reason
exact specifications for the foundatons could be pro
pared, and 1t therefore stipulated that proper
number OF piles OF given size should be driven &c 70
none of these requirements were complied with. Ito
II to Is inches in diameter do not average more than
10 inches the surface OF the mud where they
we're cut on to ree Ts 9 so D swaoa6n 5s
the piles which had been sawed on, and largo
ne s 81 not %eTS E seSF
specifications required; OF the between thrr
properly driven. The weight OF the BANNER about
onethrd less than It should have been and zach 81 is
II inches These facts learned from witnesses
OF the work and are abundanty sustained by appear
ance Of the heads OF tho piles which were cut of
The effect OF this failure properly to construct the
One of the piers before 1t was completed, sank UNI
evenly that fret leaned in one direction and then in
down and drive more piles into its foundation Other
placed upon them they leaned badly that the masonry
had be taken down to low water mark and read SO az
TO be evenly balanced on its foundations Finally.
when all Of the piers had been carefully Strengthened mp,
the supeTstuctIre was at once placed upon them and
|
was established between the piers aud the bridge that
b II the superstrucure s strong enough will Keep tho
tain the bridge. The character Of the masonry.
except those parts OF which are e,o aSSSs
too small aud the cement in which they
laid is nearly worthless as IL rapidly dssolves and
all OF has been washed out OF the joints which arc y
BILE above water bnt these have been recently reed by
pointing" probably with better cement The chaIao
ter OF the work IN the retainng-was OF the causews
at the ends Of the bridge Is also very bad Their founa
formed by dropping loose stone the mud bot
tom of the river. From those loose rubbe walls laid
without cement are raised 10 the hight required foe
cannot stand Some 80 40 feet of tie wall tho
south end OF the bridge has already failed was
pletely Frustrated by being showed out bodily by the
pressure Of earth into the water Other parts III also
| badly damaged. These walls In fact exceedingly
ance The engineer who accompanied me gives IL ss ne
professional opinion that the iron bridge proper ~ def
by the speeihcaons While II is possible that the iron
when a0d the arches ss as % ~o s's s
fact that, although theoretically IL will require the
force to crush material rs to pull II apart practically the
detection In the middle OF beam Or rod OF iron or other
material when pressure Is applied 10 It's opposite ods
will IL L. break long before the weight Is sufficient
TO crush IT, Taking this fact into consideration, the en
| neer made rough estimate. from which he concluded
that this bridge would sustain load OF 100 pounds
the strain under such load should not more than ono
sixth Of the ultimate strength Of the iron Public atten
ton has repeatedly been arrested during the past few
10y the breaking of iron bridges aud IL Is therefore
desirable that, wherever is possible. the severe
shall be applied "a these stiucres The Engineer
Department the Army has done excellent work
in Washington and vicinity, and the fact that
structure has been Oulit u,ier s supervision has always
given the people great confidence that the work has been
properly performed In this engineers OF very great
experience doubt that the Navyyarl bridge will sustain
the required load II will be very easy have Of 10
spans publicly tested before the accepted from
the contractors III stands the test that fact Will oe
complete answer To ali future criticisms; II t does not
then the weakness OF the structure will be discovered 10
fore will be too late TO correct its defects The tes
need not OF course be carried lar 10 break tne