New-York tribune. [volume] (New York [N.Y.]) 1866-1924, 1908-11-20
CALLS IT A BLUNDER
The Scientific American Comments
on BIackzceIPs Island Bridge.

on BLack1celPS Island Bridge.
Following the publication of the reports Of the
engineering experts, appointed to investigate the
charges made in The Tribune five months ago that
the BlackweIrs Island CQueensboro) Bridge was
being dangerously overloaded. The Scientific Amer
ican'' in its current issue. commenting upon these
reports under the heading. "A Monumental Blum
der says:
And so it seems that our worst fears regarding
se Gr we are oW assured thaf this the greatest
engineering work OF Us KIND IN me o S4Tq b II
was designed to carry. A little more than year
bee Bridge across the ST. Lawrence crumpled up
under its weight and fell into the river eeio%
the Biackweiis Island Bridge and ii was de-
signed same general principles wIlcl ndd
been he faulty, in some partic9naTs as qe
yeloped IN Lhe ue9ec BTase; te Rl the actual
strength of the structure be made by lndependennI
ed and Professor Burr of Columbia University and
Messrs Boiler & Hodge, bridge engineers OF this
Their reports which have recently been made pu5,-
jected the loads which it was designed to CARR
TIE abns: IN see es q ft s rgee rgs designed he
in the 9f member rising to u per ceH aoo's 'He
Very wisely. when the construction Of the bridge
%s 81 aI 3, a5sg 10 carry the great
est possible consested loading that could De Be- pqt
would be carrying $4,000 pounds Of moving weight weight
every linear foot of its length SUDSeqIeitlt.
to the completion Of the plans IL was decided that
to the demands OF the future II would be de-
accoT9no9Iare FOUR elevated Tracks upon IT'S upper
deck two extra tracks being added r 70 the in6 1--we as
very large increase in the live loads say nothing
Of an Increase IN the Strength ana ana weight u 'N
gGnS would haTf o sg e f6 b4 al fS ad
and new strain sheet drawn up showing the exact
ing throughout the whole bridge As far as we
strain sheet being accepted as correct, and pro
rata increase being made in the section OF the Var
w Wien hem Messrs Boiler & Hodge began their in
thing to do was to ascertain what were the actual
conditions of stress in the structure as built Ac-
cordingIy, they secured the shipping bills, show
ing the weight of every piece OF steel that nad
been built into the bridge checking these weights
by careful measurement OF the various members.
and from the weights as so received Dy them ana
checked. and upon the specification Ioaalng OF
Borunttu to inspect sSoWing the actual condi-
tons in the structure as IL stands to-day. -,
The results are simply appalling. Ihey maT mars l NJ
bridge as the most monumental case OF fauIty Ge-
sign in the whole history OF the art OF sa
understand that when the maximum stress s. 20
subjected determined upon no allowances were
made Tor secondary stresses IN te - TIs nam
bers (due to tendency 10 dlsIOrlI0h IA L-o i9
I bers themselves or for snow load The OMISSION
OF snow load Is Simply aIazlh 1 TOT b ~ s 1SS in
in the event OF a blizzard IKE IlaO o 1872 G1 he
which the vast floors of the bridge and al Inc me
a SrCn ~ fhfs Lad 5roTG NOT be represented By
any corresponding increase OF material In tne
members TO carry the additional burden mus I'M
say that the bridge might not be congested WITH
traffic at such time fQ TaIf b t5a cze Of
stalIing of trains and cars and olocAaae OF
That our estimate OF the magnitude Of the blum
/ der committed IN this bridge is not overdrawn
/ two reports: Professor Burr says. The result OF
! these computations shows that some OF the
carry about . per cent more than Is perInltte79
Ies also some similar overstresses in riveted
sion members in the same parts OF the bridge:
Professor Burr exhibits here as elsewhere in mis-
report tender conlIniseraflon tor Inc ne ~ ms
Gonmltted; Tor ne IallS 70 rses as shown
/ than n per cent above what Is allowed by con-
When Messrs Boiler & Hodge had proved that
the bridge if subjected TO the loading for wncn Il
had been calculated rather iscaIcuIated. by the
! Bridge Department must inevitably collapse into
the East River, they set about the calculation or a
strain sheet showing what loads the bridge actually
/ could carry without exceeding the safe limits OF
the specification and by all good engineering prac
/ tice. And what did they fnd2 That instead OF oe-
per Iiueal foot bridge Il stands today can
and hat erea ms Ire load can be safeIy GIotoed
on the bridge, oriy II the tTGgc IS caFsJ'y TTgT7
distance be maintained between the trolley cars
/ This last restriction: being Interpreted means ans
| spacing between cars be not maintained. and. as
become punched together the safety Of the bridge.
even under a lXe load z neTis IN ne iy,5e=.dI
] But how is the loading 10 be reduced 20 InIs
! extent Boiler & Hodge in their report show that
/ n can he done only bS removing from the bridge
/ the whole of the four elevated tracks which II
was designed. supposed TO be designed, u carry
/ In other words. this S24.ot0GF1 structure whose
! greatest usefulness ultimately would have con-
/ sisted in its serving d a link between the heavy
/ electric train service. whether subway OF surface
/ of greater New York, is found To De totally unnt
! for such a purpose. and must be limited TO the
/ service of trOIleys, trucks and pedestrians NO
/ elevated trains on a bridge for whose approaches
nearly half a mile Of elevated structure has al
{ ready been built
( II is the mark for apOOgtsTs, IN the en-
deavor 10 tighten gravity OF the situation. 70
/ suggest that $500 pounds foot Is a loading
/ which may never occur. That loading was adopt
1 ed as a measure of safety and as means OF COW
erfn the nevtabI growth Of traffic in me future
As measure precautton L does not lose IT'S I'M
/ DOrtance in eyes because some enc mas COM
/ T1ftted A costly blu1der in the Bridge Depart