CONFEDERATION BRIDGE MAP
Extreme ice and the well-being of lobsters determined the bridge design.
In 1997 the Confederation Bridge, one of the world’s longest continuous multispan bridges, opened, crossing the Northumberland Strait between Prince Edward Island and New Brunswick. At the time it was built, it was the only bridge of its class to be subjected to conditions as harsh as those prevailing in the frigid and windy strait. And, to meet federal criteria, it had to stand for a hundred years without retrofit, twice as long as the typical lifetime of a bridge built in more hospitable climes.
The builder, Strait Crossing, a consortium of Canadian, Dutch, and French firms, faced formidable natural and governmental obstacles in constructing the bridge. With ice migrating back and forth across the strait for a good part of the year, a phalanx of engineers had to consider not only what would happen when ice encountered the bridge, but how the bridge might affect the flow of the ice. The biggest questions concerned the bridge’s impact on “ice-out,” when the ice leaves the straits in the spring, and on local fisheries and aquaculture. The project’s environmental impact was paramount and continues to be closely monitored; even the lobsters were considereddredging of the sea bottom was timed to avoid interrupting their peak molting season. You never know what peace is until you walk on the shores or in the fields or along the winding red roads of Abegweit on a summer twilight when the dew is falling and the old, old stars are peeping out and the sea keeps its nightly tryst with the little land it loves.
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The bridge consists of 44 spans, which form 22 portals, in effect 22 individual bridges. Each of the main girders weighs 7,500 tons (6,804 tonnes) and measures 630 feet (192 meters), longer than two football fields. Placing the colossal girders down required hairbreadth precision and the loan of the Svanen, the giant swanlike (hence its Dutch name) crane used to construct the Great Belt Fixed Link in Denmark (see here). The girders are joined by drop-in spans, which are alternately hinged to avoid a “progressive collapse,” or domino effect, should the bridge be hit.
Enjoying Prince Edward Island’s short summer season once required a forty-five-minute ferry trip; the new bridge reduces crossing time to ten minutes. In operation since 1917, the ferry service ended the day before the bridge opened. For nearly seven hundred ferry employees, who received job retraining and stress counseling, the loss of the ferries was acute. For islanders and mainlanders alike, the opening of the bridge marked the passing of a way of life. Since its opening, the number of tourists is up, but given the convenience of getting to the island, their visits are shorter. Testing over the past two decades shows that the Confederation Bridge’s pioneering deep-ocean technologies are significantly effective, but determinations as to how it will shape the island’s more intangible human dimensions are still in flux.
Prince Edward Island, or Abegweit, as it is called by the native Mi’kmaq, is a tiny gem of rocky shores and picturesque fishing villages. Many visit, inspired by the writing of the island’s most famous daughter, Lucy Maud Montgomery, author of Anne of Green Gables.
To limit the brunt of the massive chunks of ice that move across the strait, each pier base is flared and surrounded by a partially submerged ice shield, forcing ice floes to ride up the side of the pier and crack into pieces. To further counter such impacts, the distance between the piers was increased from 574 feet (175 meters) to 820 feet (250 meters).