The Quebec Bridge CollapseThe Quebec Bridge CollapseAugust 29, 1907August 29, 1907

By: Dan Ford

Purpose for the bridgePurpose for the bridge

– The St. Lawrence River became a barrier to east-west transportation

– Montreal’s success was appealing– So in 1887, the Quebec Bridge Company

was formed

The Hired HelpThe Hired Help

The Phoenix Bridge Company of Phoenixville, Pennsylvania was given the contract

The Head Engineer of the project was Theodore Cooper- One of the most respected bridge builders

at the time

The Original DesignThe Original Design

Cantilever superstructure with two main supports placed 1600 feet apart

Weighed a total of 62 million poundsCooper said that this would be the best and

cheapest plan and proposal

A Change in PlansA Change in Plans

Before construction was to begin Cooper lengthened the span from 1600 ft to 1800 ft

He also modified specifications that would allow for higher unit stresses

There was no preliminary tests or research studies conducted to check these design changes

ConstructionConstruction

Erection of the superstructure got underway in the summer of 1904

Due to Cooper’s health issues he only visited the site of the bridge 3 times

This left a lack of authority on the construction site

Troubles During ConstructionTroubles During Construction

The actual weight of steel put into the bridge had far exceeded the original weight

compressive chords 7-L and 8-L of the south cantilever arm were bent

On August 27, 1907, it was reported that the deflection in chord 9-L had increased from three-quarters of an inch out of line to two and one-quarter inches in just a weeks time

Yet construction continued!!

The Collapse: August 29, 1907The Collapse: August 29, 1907

Reasons for failureReasons for failure

Financial troubles with the Quebec Company

- Inaccurate theoretical estimates of the bridge's weight

- Unchecked changes i.e. Cooper’s high-regard

The AftermathThe Aftermath

Of the 86 men who were still on the bridge at the time of the collapse only 11 survived

The Royal Commission attributed the failure to defective design and errors in the judgment of Theodore Cooper

Cooper’s career ended, and as a result he retired from public life and died in his home on August 24, 1919, at the age of eighty.

The EndThe End