The collapsed Quebec Bridge, 1907.
These past years, we’ve seen a lot of bridges collapse. What comes immediatly in my mind is of course the
bridge in Minnesota that fell and that one
in China this year, also the
“de la Concorde” overpass in Laval, and I forget
some.
It happens more often than we tend to remember, and everytime it’s a tragedy. Especially when the bridge is on construction, because more often than not, workers die. Exactly 100 years ago, August 29 1907, it was the case of the Quebec Bridge.
Since we have to
celebrate commemorate that and learn of our mistakes, I though it would be appropriate to write this article.
After four years of construction, the south part of the bridge fell apart and plunged in the Saint-Lawrence river in less than 15 seconds, and less than 20 minutes before the end of the work day, at 17h37. Of the 100 working on the structure, 76 died.
An inquiry revealed that a bad evaluation of the actual weight of components of the structure, an arrogant engineer and inadequate communication contributed to the catastrophe.
By lenghting the cantilever span by 60 meters from the original plans without taking into account the heavier than expected weight of the steel , the engineer Theodore Cooper unknowingly created a structural problem. The bridge was going from 490 m to 550 m.
The official reason: to allow the pillars to be in more shallow waters. The more probable reason: break the record for the longest cantilever bridge currently held by the
Forth Rail Bridge, a Scottish bridge, built a few years before whose
cantilever span measures mesure 520 m.
In 1906, a judgement error by Cooper scealed the tragic destiny of the bridge. He had received a report mentionning that the steel used for the construction, of lesser quality than what was originally planned, was 33% too heavy. The only logical option to fix this problem while keeping on the original plan would have been to stop te construction, demolish the structure and start over again. It was of course out of the question.
In June 1907, the workers noticed a worrisome problem: the holes for the studs were not aligned properly with the steel parts in place. In the morning of Tuesday August 27, they noticed a deformation of a few centimeter of the bridge frame. The foreman in charge of the construction site immediatly went to New York to inform his boss that the bridge could collapse any time now. A telagram was thus sent, demanding an immediate stop to the construction, but this telegram was sent to the headquarters of the company, in Phoenixville instead of Quebec City.
It seems we have a special gift to hire incompetent engineers for big projects in Quebec, don’t you find? The tradition continues.
When we take a look at the
images of the original plan of the bridge, we notice that the frame of the cantilever arms was different than the ones currently in place. Indeed, they were more curved.
It took more than two years to remove the 9000 tons of metal, of which some remains are still visible at low tide.
This first failure wasn’t enough to end the project since the economical impact to building the bridge were too important.
In 1916, the reconstruction of both cantilever arms was completed and all that was left to complete the bridge was the middle span. When it was finished, it was transported to the bridge using barges. It never reached its final intented destination however.
On September 11, 1916, it plunged in the waters of the St-Lawrence river, taking the lives of 13 workers. After the investigation, it was determined that the accident was due to a broken part of the lifting device.
The bridge as we know it nowadays was completed in 1917 and inaugurated by
Edward VIII of the United Kingdom (then Prince of Wals) in 1919. Here’s
a picture of Edward VIII taken during his visit to Canada 1919.
It is still the longest
cantilever bridge in the world.
Further readings:
-
Wikipedia article
-
Mysteries of Canada
-
Canadian Encyclopedia
