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The Quebec Bridge after the 1907 collapse, courtesy of Mysteries of Canada

The Engineer

At the age of 19, Theodore Cooper graduated from Rensselaner Institute with a Degree in Civil Engineering. He spent some time in the United States Naval Academy and in 1874 completed the St. Louis Bridge. As a famous consulting engineer, Cooper had three great projects under his belt and was looking to “crown” his career with the completion of the Quebec Bridge.(5)

The First Bridge

The Quebec Bridge Company and Phoenix Bridge Company of Pennsylvania contracted to build the Quebec Bridge over the St. Lawrence River. Theodore Cooper, a world renowned bridge builder from New York, decided to take on the project. The project called for a cantilever bridge with a main span of 1800 feet. This would pass the Forth Bridge and take the title for the longest bridge in the world. “In late 1903, P.L. Szlapaka of the Pheonix Bridge Company, had laid out the initial drawings of the bridge. His design was approved with very few changes by Cooper.”(4) With a tight budget, Cooper needed to test some of the materials, but became seriously ill before completing these tests. Cooper appointed Norman McLure, a recently graduated engineer, to oversee the project. Though at home in New York, Cooper received a letter informing him that the actual bridge weight exceeded the design by 8 million pounds.

The Quebec Bridge in 1916 after the second collapse, courtesy of the National Archives of Canada.

This extra stress was determined to be within tolerances and work continued. McLure discovered that two girders were misaligned by a couple of inches and appeared to be bent(4). He went to New York to report the information to Cooper. The workers progressed without permission and the bridge failed. In the summer of 1907, the south arm of the bridge collapsed taking the lives of 76 workmen.

A Second Disaster

The next year the companies would try again. This time Ralph Mojeski was on board and a different design was implented. This bridge would have anchor arms of 515 feet, cantilever arms of 580 feet, and a center suspended span of 640 feet. This would still be a record breaking bridge. Much more caution was taken in building this bridge.

The Quebec Bridge today, courtesy of AltaVista.com.

For example, the bridge was designed for heavier loads, calculations were checked and rechecked, and the nickel alloy steel bottom chords, although 40 percent stronger than carbon steel, were made several times larger.(3) Close to completion, the bridge's 5000 pound center span was being lifted into place when one of the four rocker arms failed. The span fell to the river below killing 11 workmen. Work commenced almost immediately after the collapse. The Quebec Bridge was finally completed in 1917 and the record still stands that the Quebec Bridge is the longest cantilever bridge in the world.

2. Lienhard, J. Quebec Bridge Failure. Accessed on April 28, 2001 at 3:00 PM. Quebec Bridge Failure.

3. The Quebec Bridge. Accessed on April 30, 2001 at 11:00 PM. The Quebec Bridge.

4. Ricketts, B. The Collapse of the Quebec City Bridge. Accessed on May 2, 2001 at 2:00 PM. Mysteries of Canada

5. Stanford Summer Engineering Academy: The Faces Behind the Bridges. Accessed on May 6, 2001 at 10:00 PM. The Quebec Bridge.




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