Quebec Bridge Collapse
Head Engineer
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Head Engineer: Theodore Cooper
Highly respected reputation
Wanted a monumental project to end his
career
Unrivalled for the tender
Overconfident
The Quebec Bridge company
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Lack of funds
Never built a bridge with a span larger
than 300 feet
Wanted “quickest and cheapest” solution
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Cooper only visited the site 3 times
Cooper appointed, Norman McLure, with
no experience, to be his eyes and ears on
site.
Pre-Construction
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No preliminary tests and research studies
done
Bridge was extended an extra 200 feet
without any calculations
No recalculations of assumed weights for
the bridge after revised specifications
Theoretical estimates of weights used
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Construction continued without dead load
being calculated
Phoenix Bridge Company’s inspector of
materials projected weight of the steel
was 11 million pounds heavier than
previously estimated.
Cooper concluded that Edwards was
wrong by 7 to 10%.
This was after much of the bridge was
fabricated or in place
During Construction
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Horizontal compression members started
deflecting
Unable to line up members for riveting
As span increased many weight-bearing
lower chords were still unriveted
Eventually two of the chords from the
south cantilever arm bent
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Chief engineer in Phoenixville insisted that
these chords were bent when they left the
shop and that they were still serviceable
Cooper sent word to Phenoix Bridge
Company to suspend construction which
was ignored
Collapse
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Two compression cables failed.
Sudden collapse!
75 were killed
2nd Collapse
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A second collapse occurred in 1916
Similar design but two and a half times
heavier than its predecessor
During the construction the central span
which was pre-fabricated dropped into the
river while being lifted into place
11 men died.