page_title: Extradosed bridge
section_title: Canada
hierarchical_section_title: Extradosed bridge / By country / Canada
caption_attribution_description: English: en:North Arm Bridge as seen from the front of a SkyTrain in Richmond about to traverse the bridge.
context_page_description: An extradosed bridge employs a structure that combines the main elements of both a prestressed box girder bridge and a cable-stayed bridge. The name comes from the word extrados, the exterior or upper curve of an arch, and refers to how the "stay cables" on an extradosed bridge are not considered as such in the design, but are instead treated as external prestressing tendons deviating upward from the deck. In this concept, they remain part of the main bridge superstructure.
  Compared to a cable-stayed or cantilever-girder bridge of comparable span, an extradosed bridge uses much shorter stay-towers or pylons than the cable-stayed bridge, and a significantly shallower deck/girder structure than used on the girder bridge. This arrangement results in the typical extradosed "look" of a fan of low, shallow-angle stay cables, usually with a pronounced "open window" region extending from the sides of each tower.
  The extradosal bridge form is mostly suited to medium-length spans between 100 m and 250 m, and over fifty such bridges had been constructed around the world as of 2012.
context_section_description: The North Arm Bridge is a transit-only bridge of SkyTrain Canada Line, connecting Vancouver with its suburb of Richmond crossing over the Fraser River. The bridge went into service on August 17, 2009, coinciding with the opening of the Canada Line.
  The Golden Ears Bridge, crosses the Fraser River between the municipalities of Pitt Meadows / Maple Ridge and Langley. It is the longest extradosed bridge in North America. The bridge opened to traffic on June 16, 2009.
caption: North Arm Bridge, Canada 2009
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