The sun. [volume] (New York [N.Y.]) 1833-1916, 1894-12-09
THE NORTH RIVER BRIDGE.
ENGINEER HILDBNBRAND,s PEA
FOR THE s~USPENSION PLAN

foot tant1erer with n River r~ier-douid
he Buit as ouickly and Wouis Be SAFER.
Engineer w. Hildenbrand, who prepared plans
for a clear span suspension bridge across the
North River. does not think there is much in
the objections made by the New York and New
Jersey Bridge Company to the two Government
reports in which a clear span suspension bridge
Is favored, instead Of a 2.00O-foot cantileyer
with one pier In the river. The Commission
appointed by the President said that such A
bridge would cost $4,000, 900 mere than the
cantilever. Mr.. Hildenbrand. In a subsequent
report to the Chamber of Commerce, cut the
estimate down to s24,o0 900, or $4,000
600 less than the cantilever, and showed
that the cost might be kept down to s2i, OOO,-
900. Lastly the Board Of Engineers appointed
by Secretary Lamont put its cost at 500, OOO.-
600. the span to be 5000 feet. In reply the
bridge company's representatives said that a
single span suspension bridge would cost three
times as much as a z. 0OO-foot cantileyer; that its
erection would occupy FIVE years longer; that
II could barely sustain Its own weight, and that
fast heavy trains upon II would be out of the
question; that 1t was impossible financially. and
that It was q question of having q 2,0O0-foot
cantilever or no bridge at all.
"If Secretary Lamont" Engineer Hide brand
said in reply TO these arguments. should decide
against q pier, and II the bridge company should
refuse TO build q bridge without q pier, Il IL by
no means proved that the public would forever
be deprived Of . bridge. Undoubtedly another
company would speedily be formed to take up
the matter, and other capitalists will have faith
H. the new company II the present prospective
capitalists should withdraw their patronage
from any design differing from that Of the cngi-
neer of the bridge company. II there is money
in n see, 900. 900 cantilever bridge there is GER
tainly money In q $23, 900, 900 suspension bridge.
ITO make the matter fully understood / beg
TO remark that this Is not a discussion on the
comparative merits OF a cantilever and a sus-
pension bridge. 1t is merely a question whether
the proposed North River bridge shall be built
with or without q pier in the river. II the
Bridge Committee would contemplate a bridge
without a river pier, the type of construction
would be exclusively their own business, and
nobody would attempt to interfere. It is,
however. universally conceded by engineers
that the suspension type would be the only
practical plan for q single span bridge.
The practicability of q 2,000-foot canti-
lever has never been doubted by any
body. but the Chamber of Commerce, with
tho object to preserve the New York harbor
from obstruction, has attempted to prove that a
single span suspension bridge is also safe and
practical. and can be built at reasonable cost.
AN argument against q suspension bridge
put forth by the company is that towers and
butuoEokCo 70 hnlshCu btlOTo Cuult-
making can begin. while In q cantilever bridge
the erection of the truss can be commenced
upon merely finishing the tower, saving there
with the interest for a certain time of the CAPT.
tai required for building the anchorages. This
when we examine the matter2 Referring TO
the report OF the Board of Engineers. they place
bridge at 1000 900. the cost Of the west tower
foundation at $4,000, OoO, and the cost OF the
river pier foundation for the cantilever at So
Nl0 ono In other words In addition In
what Is common to both structures, the
suspension plan requires the expenditure Of
SiO,00O,0O and the cantilever plan the expendi-
trre. OF S0,00O,0 900 before the superstructure
can be commenced. Assuming that the excess
tlre would be necess AIRY during the whole time
OF cable making. or for eighteen months, the
600: but n greater loss Of interest will fall on
the cantilcyer plan. II will certainly take more
make one OF 100 feet. Placing this difference
OF tiTne very moderately at six months, the
FOR hall a Year or $4,000. subtracting there.
from the suspension plans loss OF $4,000, there
and none To the suspension bridge.
The argument OF triple the cost for a suspen-
sion bridge over a cantilever Is made by the
bridge company without any PROOF by figures.
The calculations OF the TWO boards Of engineers
show conclusively that the suspension bridge OF
1900 Ieet span will cost less than q cantilever
bridge OF 1000 feet span, with "a pier requiring
a foundation $50 feet deep.
In regard tn the time Of erection, would not
venture to give the actual time for either struc-
ture, but the following figures will give a correct
take at least six months more than that Of the
suspension bridge. The time for the construc-
.iE stoned of the be susR Shsasn G montb was which Si,
gives an ample margin over the probable
time, Judging from the precedent Of the
brooklyn bridge, according To which II should
not require over eight or nine months. After
the cables are finished, it is absolutely certain
will require much less time than the erection Z
the cantilever superstructure, The cantileyer
Piece, while the finished cables form n bridge
which enables the erection OF the superstruc-
desired. II is, therefore, possible, though It is
not probable, that such ideal arrangements
sreet DC mnae: = o . w Snnaps trm u IN less Than
one-tenth the tire necessary for erecting the
cantilever superstructurs. Sonsiaerlng the
excess of time, and the erection OF the other
parts of the superstructure to be equal In both
for the suspension bridge; but considering
that the erection of the floor system OF the sus.
pension will &c, on much quicker than that OF
the cantilever, there is no reason to suppose that
To bnild a suspension bridge will take more time
Is that IL will require even less time.
The Brooklyn company has also assaiied lie
:peaHin 9. both P types Of P'' STidse' "i Il properly
ssis The question on q I %Srs s e. Tssi
Conditions. and IN this respect a suspen,
sion bridge is the safest OF all eonstTuctions, as
Is stated also In the report of the Government
engineers. A suspension bridge, is In a stable
equilibrium; 1t may he subjected to any degree
OF distortion or side oscillations and will come
back to its original position, while a little or lesser
degree OF distortion would prove fatal 10 any
other type OF bridge. The Engineering Ners
has in each number IA record OF bridge accidents
amounting to two or three. every week. High
way and railroad bridges of different construc-
lions are reported TO have fallen down for a va
rlety of reasons, but, though there are many
suspension bridges in this country, such acct
dents never refer 10 suspension bridges. The
only accidents that happened 10 suspension
bridges are the destruction of the Wheeling
bridge In 1854, that of the Clifton Niagara
bridge In 1850 or Whereabouts. OF a small foot
bridge AZ Brunswick. Me, in lS02, and OF the
Milford. Pa, bridge in 1855. The last was car
ried away BY an ice gorge. The first three were
destroyed by violent tornadOes, but in each case
only the floor WAS torn away, while the towers,
anchorages, and cables. so to say, the backbone
and most expensive part of the bridge, remained
Intact. This is different from the well-knOwn
iay bridge disaster in Scotland, where nothing
was left to indicate that there ever was a bridge
Ut that place.