Quebec Bridge

From Freepedia

The Quebec Bridge in Canada crosses the lower Saint Lawrence River to the west of Quebec City, and Levis, Quebec.

The Quebec Bridge is a riveted steel truss structure and is 987 meters (3,239 feet) long, 29 m (94 feet) wide, and 104 m (340 feet) high. Cantilever arms 177 m (580 feet) long support a 195 m (640 feet) central structure, for a total span of 549 m (1800 feet), the longest cantilever bridge span in the world.

The bridge accommodates three highway lanes, one rail line, and a pedestrian walkway; at one time it also carried a streetcar line. It is owned by the Canadian National Railway.

Contents 1 History 1.1 Background 1.2 First design 1.3 Collapse of August 29, 1907 1.4 Second design 1.5 Collapse of September 11, 1916 1.6 Completion 1.7 Post-completion history 2 Trivia 3 External links

History

Background

Before the Quebec Bridge was built, the only way to travel from the south shore of the St. Lawrence in Levis to the north shore at Quebec City was to take a ferry. By the 1890s, a bridge was needed. A March 1897 article in the Quebec Morning Chronicle noted:

The bridge question has again been revived after many years of slumber, and business men in Quebec seem hopeful that something will come of it, though the placing of a subsidy on the statute book is but a small part of the work to be accomplished, as some of its enthusiastic promoters will, ere long, discover. Both Federal and Provincial Governments seem disposed to contribute towards the cost, and the City of Quebec will also be expected to do its share. Many of our people have objected to any contribution being given by the city unless the bridge is built opposite the town, and the CHRONICLE like every other good citizen of Quebec would prefer to see it constructed at Diamond Harbor, and has contended in the interests of the city for this site as long as there seemed to be any possibility of securing it there. It would still do so if it appeared that our people could have it at that site. A bridge at Diamond Harbor would, it estimated, cost at least eight millions. It would be very nice to have, with its double track, electric car track, and roads for vehicles and pedestrians, and would no doubt create a goodly traffic between the two towns, and be one of the show works of the continent.

First design

The bridge was built by the federally-owned Quebec Bridge and Railway Company, as part of the government's National Transcontinental Railway. Construction was contracted to the Phoenix Bridge Company of Pennsylvania and began in 1903 under the direction of famous American engineer Theodore Cooper after the federal government allocated funding. It was designed to span the river's shipping lane and measured 26.5 meters (67 feet) wide, carrying two railway tracks, two streetcar lines, and a two-lane road.

Collapse of August 29, 1907

By 1904, the structure was taking shape. However, preliminary calculations made early in the planning stages were never properly checked when the design was finalized, and the actual weight of the bridge was far in excess of its carrying capacity. All went well until the bridge was nearing completion in the summer of 1907, but then the local engineering team under Norman McLure began noticing increasing distortions of key structural members already in place.

McLure became increasingly concerned and wrote repeatedly to Cooper, who at first replied that the problems were minor. The Phoenix company officials were claiming that the beams must already have been bent before they were installed, but by August 27 it had become clear to McLure that this was wrong. A more experienced engineer might have telegraphed Cooper, but McLure wrote him a letter, then went to New York to meet with him on August 29, 1907. Cooper then agreed that the issue was serious, and promptly telegraphed to the Phoenix Bridge Company: "Add no more load to bridge till after due consideration of facts." The two engineers then went to the Phoenix offices.

But the message had not been passed on to Quebec, and now it was too late. That same afternoon, after four years of construction, the south arm and part of the central section of the bridge collapsed into the St. Lawrence River in just 15 seconds. Of the 86 workers on the bridge that day near quitting time, 75 were killed and the rest were injured. Of these victims, 33 were Mohawk steelworkers from the Kahnawake reserve near Montreal; they were buried at Kahnawake under crosses made of steel beams.

Second design

After a Royal Commission of Inquiry into the collapse, construction started on a second bridge, this time with Ralph Modjeski as Chief Engineer. The new design was still for a bridge with a single long cantilever span, but a much more massive one.

Collapse of September 11, 1916

Disaster struck again on September 11, 1916, when the prefabricated center section was being raised into place between the rebuilt cantilever arms. The collapse killed 11 men. This time the inquiry determined that the fault had been in the construction process, and the replacement span was built to exactly the same design.

Completion

Construction was ultimately completed in August 1919, at a total cost of $25 million. On December 3, 1919, the Quebec Bridge opened for rail traffic, after almost two decades of construction. Its center span of 576 meters (1890 feet) remains the longest cantilevered bridge span in the world and is considered a major engineering feat.

Post-completion history

The bridge was designed and built primarily as a railway bridge, but the streetcar lines and one of the two railway tracks were converted into automobile and pedestrian/cycling lanes in subsequent years.

The bridge was declared an historic monument in 1987 by the Canadian and American Society of Civil Engineers. On January 24, 1996, the bridge was declared a National Historic Site of Canada.

The bridge is privately owned by Canadian National Railway, although CN receives federal and provincial funding to undertake repairs and maintenance on the structure.

Trivia

• The next longest cantilever bridge spans are on the Forth Bridge over the Firth of Forth in Scotland, completed in 1890. This has two main spans each just 90 feet (27 m) shorter than that of the Quebec Bridge.
• Some have claimed that a portion of the collapsed bridge has been used over the past century to smelt rings used in the Iron Ring issued in the Ritual of the Calling of an Engineer ceremonies, administered for graduating Canadian engineering students. This is possibly apocryphal, as the bridge was steel, not raw iron. Nonetheless these rings, voluntarily carried on the little finger of the working hand of professional engineers in Canada, are meant to serve as a reminder to engineers of their social responsibilities to follow the ethical requirements of their profession.
• The Pierre Laporte Suspension Bridge opened in 1970 just upstream to accommodate freeway traffic on Quebec Autoroute 73.

External links

• Familiarity breeds forget
• Ritual of the Calling of an Engineer
• The Iron Ring
• Iron Ring myth and tradition