The sun., 1916-09-16
POSSIBLE CAUSES AND LESSONS or
THE QUEBEC BRIDGE DISASTER.
A Thorousheoins Examination Of the Structure by Witnesses Of the FAN
Of the Central Span Leads to OptinisaLe Conclusions.


to start at the root. Total f,iip,.
would readily follow.
Now that the accident has occn,,.,
1t is easy to suggest that thc shoe
might better have been built OF ro,lo,
sections and plates; that the bearinp,
instead Of being in semi-cylindr,c,,
halves. might have been pin hole'
that some auxiliary support mIpb.
have been provided TO supplement, ,bs
main supporting detail. But the se,,
judgment Of the best bridge engines,s
IN this continent said that tho do
tail was amply sufficient for tho in.
tended service Something won,
wrong. but 1t was not through lacl =,
ability Of those responsible for IN,
work, nor can IL he said that ,bo
They were tested, and Under yrest,r
loads thar they were presumahlv
carrying when the crash came. 70,
they supported the span at SiIlcry.
1t Is natural to look for some Undue.
ing cause, even IL the breakare NJ
casting he accepted as tho most plaus,
ible explanation: some swaying " tho
structure. induced by "a puff of v,na
the unequal working Of the Jacks Sc
Suffice II to a that there is no ,y
dencc of such An inducing cause. \,
freshening Of the wind. which was ycrg
light. was felt. The jacks were no,
operating. the structure had h,o,
pinned fast for a full two minutes no.
fore the drop came. Vibration from
a or hoists on tho can,iloyer
arms. II any were working at the tim,
may be considered negligible.
The loss Of the span. while ii NAV q
the lay mind cast discrclit on ,bo.s
responsible for the work. m rcal,r
put the remaining parts of the sfruc.
ture to a most extraordinary test. and
SO proved the ability Of the de- sne,,
and builders. The suspension " tie
span from the cantilever arms de.
flected their ends between nine and
ten inches. The application Of tn
load was gradual. Its release. un n.
contrary. was sudden. Men on n.
ends were thrown down. whlc lie
vibration lasted long enough for or,
nan to run about $50 feet toward Oh.
anchorage. AT least the fun deiicct.on
must have beer recovered. and rto,,.
ably the momentum carried tho ends
above the normal unloadcd position.
Yet the cantilevers stood and Ar.
parently unchanged. F'urthcrmpre.
the known details as to the siicrcs.Iv.
steps in the plunge, combined witt 'h,
evidence Of the two diagonal, upp,.
site overstresscd hangers. show .Aa,
the very large overloads must ha,,
been thrown into at least the dow.
stream truss on the south cant.'.y
and the upstream truss OF the nor
cantilever. But there is no appa-. r.
evidence OF distress.
The bridge. which has TINS -.
ceived n setback. for it is only a -.
back. is extraordinary in So many u.
spects that Il, Is a pitv IL should ~
have come through with a clean g.
ord. The K-truss design. the nav.
lous precision and finish of the sh.'
work. the ingenious and highly sr.
cessful erection methods-cach won't
have made the %structur" ro,lh
among steel bridges even thoUsN 49,
span were less than the record.
Engineers. who must constor''v . .
unknown factors in breahir. PEN
paths. will not lose faith in Their lre'
rem at Quebec. Backed hy thor
termination and ability. tho span y
he rebuilt and successfully erected