New-York tribune., 1908-05-12
NEED OF INQUIRY INTO
NEW UEIGHTS IMPOSED.
Uhen mplcted Carrying Members
Must Bear Much Greater Stress
than That Under H'hich the
Quebec Bridge Cola psed.


sS242as5. and a few weeks ago the Board Of
Aldermen authorized the expenditure of S1,2o0.-
90 more TO complete the work. The fact that
This s231o0G0 in excess OF the contract price
represents additional weight Of material put into
the superstructure has aroused the interest and
apprehension Of bridge engineers and those
customed 10 figure upon bearing strains and
stresses in bridge construction.
From competent engineer, in a position TO
know what he is talking about, The Tribune has
obtained facts which tend to show that the addi
tioual load imposed upon the superstructure may
seriously interfere with the safety of the bridge.
These facts have been substantiated in a gen.
eraI way through g subsequent investigation
made by The Tribune into the amount of money
expended upon the superstructure in excess Of
the contract price. This excess expenditure.
amounting TO S2.31oopo, represents additional
weight OF material put into the sUperstructure Of
the bridge. If the terms Of the contract have
been lived up 10 by the contractors.
The report Of the commission Of engineers ap-
pointed investigate the failure of the cantilever
bridge at Quebec Canada, which resulted in its
fall last August, shows that the cause of the
disaster overlooking of the structure
beyond its carrying capacity by the weight of
material used in its construction II looks as If
similar course had been followed in the erec-
tion Of the Blackwell's Island Bridge, which is
also q csntilever structure.
The question whether the Blackwell's Island
Bridge is being overloaded beyond the safety
point is essentially one for bridge engineers to
determine. But in view Of the disaster which
heteu the Quebec bridge from an exactly similar
cause, and the divergent views expressed by
competent saIthorities about the safety of the
Brooklyn Bridge il z heavier load than Il is at
present carrying IS imposed upon it the facts
obtained given 10 the public In order that
structure by competent engineers entirely inde
pendent Of the Bridge Department of the city
may be secured.
Az ENGINEERS VIEW.
The facts alleged from an engineering point Of
view In connection with the Blackwells Island
Bridge are outlined in the following statement
made The Tribune by engineer Of such
experience as to command respectful attention:
The engineering papers of a few weeks ago
published the report Of tie Canadian engineers
upon the fall OF the Quebec Bridge. 1t VIII be
recalled that this bridge over the St Lawrence
River was to be the largest bridge III the world
II designed and built by the Phoenix Bridge
Company, and the main span Was being erected
when II fell on August p l9OI. About seventy
five men were killed or drowned and the bridge
total loss The report in question Is
striking example Of what report should be.
and quite unlike the whitewashins reports We
are familiar with in this country
The engineers who investigated this bridge
failure went into the matter fairly and fully,
and their conclusion was that the entire fault
az ir7 choosing or allowing unit stresses that
were high. In other words. Mr.. Cooper, as
consulting engineer, permitted to be fabricated
md erected srrrIct1IraI members of this bridge
that we're too light for the load imposed upon
them The investigation disclosed that the
member which failed and allowed the bridge TO
fall loaded with about $4,000 pounds d
square inch, and that this only three-Quar
Of the calculated load
Furthermore. a quarter sized model OF the
member which failed was tested in the Phenix-
vile shops. and il also failed at $4,000 pounds
square inch.
five Of this report which states that Mr.. Cooper
"UnquestionabIy increased the unit stresses, but
20 a poin: beyond those already adopted by
the Bridge Department cf the City of New York
The onlv New York bridge comparable in size
and type to the Quebec Bridge is the BlackweIs
Island Bridge. whose spans have recently been
Joined. Who designed and calculated the Black
wells Island Bridge ! do not know, but GER
tainly the New York Bridge Department never
had in its employ an engineer compare bic in
-eputation with Theodore Cooper; and when It
: undertaken TO defend bolster up fatal
error of Mr. Coopers by saying that he followed 1
p precedent Of our city Bridge Department such |
support Is Ike leaning upon broken reed
Z appears from the Canadian Commissions : |
report that when erected the Quebec Bridge eX- |
oeeded the calculated weight as follows:
Suspended arnl.................18Go
tsutileyer arm -----...-..-..... $50
Anchor rarIn....................S
I IS well known that the BlackWells Island |
Bridge a. erected exceeds its estimated weight |
myself in this report and it's surprising figures |
SO far to check Up and compare calculated |
stresses in that member of the Quebec Bridge |
which failed with the corresponding member or
the Blac<uelIs Island Bridge, and { find that |
tne latter exceed the former by more than a |
thousand pounds square inch.
can therefore view the situation aS regards |
The safet, Of the BIackwells Island Bridge in |
none other than the most serious light. and 1 |
fhsnk tho public should be assured by those in |
charge # the bridge just what the stresses are |
ih the lower chord Of the bridge erected. and |
What the ultimate stress VIII be and how far |
These exceed the calculated stresses used in the |
resisn q the members.
The financial record in connection with the
erection n the steel superstructure Of this bridge
tcars ort in ? general way the conclusions
iived - by this engineer in his statement The
original estimated cost Of the bridge with ap
breaches Was s1245e 500 The actual cost when
completed vii he about s23 100000. The con-
tract for tho steel superstructure awarded
Nag s5.s2o cg5 The amount expended upon the
'1I,erstruct7sre to date has been $6.242.S95 and
'hore has been authorized 70 complete the work
S-9a,J0J tha. las not yet been expended.
GREAT INCREASE N WEIGHTS.
'rha original contract FOR the superstructure
aas awarded TO the Pennsylvania Steel Com
Ia1y on Noyernbe: 90 1908 Tie specification
ipon which tenders aere asked called for the
erection Of the superstrueture at 50 much a
Pound of material supplied 1t was. therefore.
upon the basis OF tn weight of material put into
lie bridge that the contract was awarded.
The record shows that eerly In 1907 the Board
~ Aldermen authorized the awarding of a sup
Elemental contract 20 the original contractors,
without public letting for S3601D. This Was
i9r The specific purpose Of providing additional
ridley tracks and foot passenger walk upon
lie bridge The money has used, now es CT.