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Originally Posted by someone123
It was fine until it got hit by a hurricane type storm, and they come around every 5-10 years or so.
The bridge may not really have been such a tragedy if it was planned as an affordable semi-permanent structure. A bridge like the Brooklyn Bridge would have been a national level megaproject back then, and let's be honest about the chances of 19th century Canada paying for something like that in NS...
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Halifax was still fairly prominent in Canada in the 19th century (though things were changing...), but yeah, the Brooklyn Bridge was not happening in Halifax at the time.
Given that east coast Canada is the only part of the country exposed to hurricanes, and a bridge had never been built across Halifax Harbour previously, one would surmise that the expertise involved with the design and building of the structure would have predicted normal forces (currents, ice, degradation, etc.), but perhaps didn't have enough experience with cyclical wind-driven waves and storm surge to understand what needed to be done to anchor the bridge in extreme conditions.
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Intercolonial Railway engineer P.S. Archibald designed the bridge in a concave form with the convex facing Bedford Basin in the hope this shape would help the bridge withstand ice slides each spring.
A Dartmouth man, Duncan Waddell, was in charge of construction for the huge stone pier upon which the swing section or “draw” of the bridge would rest, so vessels could be allowed to move into Bedford Basin. The stone pier, located near the Dartmouth shore, was constructed in about 35 feet of water, by driving piles into the gravel bottom to a depth of five or six feet. These acted as guides for building the pier, which was to hold the bridge, being built by the Starr Manufacturing Company of Dartmouth.
The wooden trestle-work of the bridge, constructed by M.J. Hogan of Quebec, rested on eight foot stone-filled cribs, spaced on the harbour bottom every 10 feet (3.0 m). The piles were then secured to the cribs. As the depth of the water was about 75 feet the piles had to be built in three sections, and spliced with eight-inch deals (basically an 8″ long plank) spiked into place. This proved to be extremely weak, especially when no form of side-bracing was used.
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https://blog.halifaxshippingnews.ca/...0of%20Halifax.
The linked article (by forum member Ziobrop - who hasn't posted here since 2019) stated that this hurricane also caused damage to "wharves and shipping", so one would surmise that it was a significant storm, as wharves would typically be built as permanent structures.
The second structure disappeared in quiet conditions. Details are in the quote below from the same article.
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Suggestions were put forward by Dartmouth Town Council that it would be better to construct the railway line along the shoreline from Bedford to Dartmouth, rather than rebuild the bridge. However, the federal government decided to rebuild the structure, stating that the land route was not “deemed advisable.” Like the first bridge, it was poorly constructed and not braced. This time it was built in a straight line and thus made much shorter. Completed in 1892, the contractor was Connor’s of Moncton, New Brunswick.
About 2:00am, on July 23, 1893, almost two-thirds of the bridge slipped into the water. The last train had crossed about 6 hours prior. The cause of the breaking away of the Narrows Bridge was to be the result of sea worms. It was discovered that the piles were worm-eaten almost through between high-water and low-water mark. When the last train went over, it is assumed that these rotten supports gave way, but remained resting on the surface. Then, when the tide rose, the bridge desk floated up and the whole thing swept away.
The loss of the second bridge then led to the establishment of the rail line to Windsor Junction in 1896. The third harbour crossing is the Macdonald bridge.
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These two failures and the subsequent line to Windsor Junction are probably why a rail bridge over the harbour was never attempted again. In fact it took over 30 years before any major discussions about a harbour crossing happened again:
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The firm of Monsarrat and Pratley were engaged to carry out studies of a possible high-level highway bridge linking the 2 sides of the harbour as far back as 1928. The bridge location between North Street in Halifax, and Thistle Street in Dartmouth was approved by Dominion Authorities and the British Admiralty in 1933. The 1945 master plan for Halifax assumed that this would be the location for the bridge, and suggested widening North Street to accommodate traffic. Dartmouth’s master plan of 1945 also assumed this would be the location.
The bridge was designed by Philip Louis Pratley, one of Canada’s foremost long-span bridge designers who had also been responsible for the Lions Gate Bridge in Vancouver. By the time design work began in 1950, he was working alone. The contractor was Dominion Bridge Company Ltd. When erected at a cost of CAN $10.75 million, the Macdonald Bridge was the second longest span of any suspension bridge in the British Commonwealth, after only Vancouver’s Lions Gate.
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It's a fascinating article.