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Confederation Bridge: History, Type & Facts

Instructor: Christopher Muscato

Chris has a master's degree in history and teaches at the University of Northern Colorado.

The Confederation Bridge is the longest to span water...of a certain kind. In this lesson, we'll check out the history and design of this structure and see how it came to be.

The Confederation Bridge

Every type of structure presents its own unique engineering challenges. Skyscrapers are hard to build because they have to support so much vertical weight. Auditoriums are challenging because they require immense, open interiors. Palaces are tough because if the king doesn't like it, he'll throw you in the dungeons. So, they each have their obstacles.

However, bridges present an entirely unique challenge: building without a firm surface.

The entire point of a bridge is to cross something that cannot be easily walked across. Some of the hardest construction in the world is that which occurs over water.

In Canada, one such engineering feat was accomplished with the Confederation Bridge, which connects Prince Edward Island to mainland New Brunswick over the Northumberland Strait. Normal maritime construction is hard enough, but this is Canada we're talking about. The Northumberland Strait is often enveloped in ice. At 8 miles long, it's the longest bridge over ice-covered water in the world, making it a uniquely impressive feat of engineering.

The Confederation Bridge
Confederation Bridge

History

Canadians had been debating the best way to cross the Northumberland Strait for a long time. As a condition of joining the newly organized Dominion of Canada in the 1870s, political leaders of Prince Edward Island insisted that the government provide transportation services over the Strait.

Why didn't they want the responsibility? Like many bodies of water that are eventually bridged, ferries across the Strait were often delayed. In this case, however, it wasn't due to high traffic or congestion; it was due to all the ice. Ships could get stuck for days, with no service running between the island and mainland.

Over the years, the quality of ships improved enough to handle the Strait, and no bridge was built. Partly this was because people couldn't agree on how to pay for it, or how to build it. Partly it was motivated by fears that increased transportation would overcrowd the island, straining its resources and easy-going culture.

As complaints about the ferries increased in the 1970s and 1980s, however, the debate over the bridge picked up. After a lengthy campaign to convince the islanders that the structure would mean lots of tourist money without overpopulating the towns, support for a bridge passed with 59.5% of the vote in 1988.

Design

Approving the bridge was one challenge, but designing and building the thing would be an entirely different task. Due to the length of the span that needed crossed, the designers decided on a multi-span box-girder bridge, in which concrete piers would support rectangular steel and concrete girders holding the roadway.

The design was broken into three parts to make it more manageable:

  1. a 14-pier west approach
  2. a 7-pier east approach
  3. a main section of 44 piers over the bulk of the Strait

Beyond the size, there were other considerations for designers to deal with as well, notably driver safety in an area where wind, snow, ice, and rain are all common throughout the year. To deal with these concerns, a special road surface was developed that would reduce the spray of vehicles when water was present. Three foot concrete barriers served as windbreaks, and over 7,000 drain ports were built along the roadway.

In addition, the bridge curves rather than taking a straight line, a design feature that some experts believe helps drivers stay attentive and alert, especially when crossing something as potentially hypnotic as the rolling sea.

As an additional feature, the oddly shaped bases of the piers are supposed to help break up ice sheets
Confederation Bridge piers

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