With the recent Interstate Highway bridge collapse in Minneapolis, Minnesota I remembered another tragic one that occurred here in Canada.
The Quebec Bridge across the St. Lawrence River at Quebec City and Levis, Quebec was constructed from 1904 to its opening on December 3, 1919. During this time it suffered two tragic collapses with the first one being the worst.
It is the world’s longest cantilever bridge span at 1800 feet (or 549 metres).
Construction had started in 1904 without the final drawings having been checked and signed off by an engineer. After almost four years of construction engineers suddenly realized that actual weight of the bridge was far in excess of its carrying capacity. An emergency meeting was held and the senior engineer agreed and told the construction engineer not add anymore load. However, the message did not get passed on to the crew at Quebec. On the afternoon of August 29, 1907 near quitting time, the south arm and part of the central section collapsed into the St. Lawrence River in just 15 seconds. The height of the collapse was from 150 feet above the river. At the time 86 workers were on the bridge, 76 were killed and the rest were injured. The Kahnawake reserve near Montreal suffered the most. Of the victims, 33 were Mohawk steelworkers from the reserve.
A Royal Commission of Inquiry was held and then construction begun on a second bridge. The new design was the same except the cantilever span was more massive in design. On September 11, 1916 the central span was being raised into position. It fell into the river killing 13 workers. This collapse was not engineering related, but rather a construction accident. Still the builders must have started to wonder if the bridge was jinxed.
Finally construction was completed in August 1919 at a cost of $25 million dollars and 89 bridgeworkers lives.
This disaster spurred the formation of the modern associations of engineers that today licence and administer the certification of professional engineers. The government was getting ready to do this on their own, but the engineers to their credit took the initiative.
Today the bridge is still the world’s longest cantilever bridge and is considered a major engineering feat. On January 24, 1996 the bridge was declared a National Historic Site of Canada. Also a ceremony was recently held in the Kahnwake reserve to honor the 33 Mohawk casualties of the collapse.
It seems that Theodore Cooper, a renowned bridge builder from New York, who was overseeing the bridge construction made several errors in judgement. When he reviewed the final drawings he saw that there was a critical design error. He rationalized and told himself – no problem. This avoided the embarassing prospect of having to start construction all over again. After all his reputation was a stake. By the time this error manifested at the construction site it was too late. Below is a picture of the bridge when steam locomotives were the primary users.