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March 14, 2002 Building bridges over the St. Lawrence River was challenging



Hugh McQueen

Professor Emeritus Hugh McQueen

Photo by Andrew Dobrowolskyj

by Lisa Harding

The bridges of Montreal and Quebec City look great on postcards and feel as though they have been part of our landscape forever, but they were notable for technological achievement — and major disaster.

No one is more fascinated with the history of these bridges than Hugh McQueen, professor emeritus of mechanical engineering, who taught about them as part of the social aspects of engineering course at Concordia. He spoke about them on March 5 as part of Engineering Week.

Although it’s hard to imagine the Island of Montreal without bridges, he said, before 1859, when the Victoria Bridge was opened, there was only a ferry to and from the South Shore. “Bridges were considerable triumphs, and Canadians did these bigger bridges very well,” he said.

The Victoria Bridge was initially a box girder or tubular bridge, and a vital railway link to Montreal’s South Shore, where there were four major railway lines.

McQueen showed what an enormous undertaking building the Victoria Bridge was. “Nine thousand tons of wrought iron were brought from England, already pre-drilled and ready for the 1.5 million rivets it took to hold the 2.5-km structure together.”

This bridge had a relatively good safety record, for the time. Only two men died during the five years it took to build the structure, by drowning in the St. Lawrence River. In 1898, the single-track tube was replaced by a double-track steel truss bridge with twin roadways, the first road across the river.

The Quebec Bridge over the St. Lawrence at Quebec City had a much more dramatic history. In 1907, a half-finished bridge designed by the U.S.-based Phoenix Bridge Company collapsed into a heap of twisted steel soon after its completion, taking 86 lives.

The federal government investigated, and found that the design had been changed to add extra length, but it failed to increase the buckling resistance of the lower beams.

In the second attempt, taken by a Canadian company, the two diamond-shaped cantilevers upporting a mid-span adopted a novel K design used around the world. Unfortunately, one of the jacks broke while raising the middle section. It fell into the river, killing 16 people. However, since its repair, it has been operating successfully, and is the longest cantilever span in the world.

Some fascinating photos illustrating the construction of the bridges, some of them quite old, are part of a display on the second floor of the downtown Webster Library.

McQueen believes that if more bridges are built in the Montreal area, they would increase traffic congestion. Instead, he would like to see a ring road along the South Shore with a bridge far to the west, so that those who want to can bypass Montreal altogether.