A. Murray MacKay Bridge, Halifax, Nova Scotia
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N 44° 40.667 W 063° 36.717
20T E 451499 N 4947339
The A. Murray MacKay Suspesion Bridge links the Halifax Peninsula with Dartmouth, Nova Scotia. Opened on July 10, 1970, it was the first suspension bridge in North-America to use an orthotropic plate deck in its construction.
Waymark Code: WMJG0Q
Location: Nova Scotia, Canada
Date Posted: 11/13/2013
Views: 10
The A. Murray MacKay Bridge measures 1,200 m (3,900 ft) with the total of all suspended spans being 739.9 m (2,427 ft) in length, carrying four traffic lanes with posted speed limits of 70 kilometres per hour (43 mph). Pedestrians and bicycles are not permitted on the A. Murray MacKay Bridge; they may use dedicated lanes on the Angus L. Macdonald Bridge instead.
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Orthotropic Deck
An orthotropic bridge or orthotropic deck is one whose deck typically comprises a structural steel deck plate stiffened either longitudinally or transversely, or in both directions. This allows the deck both to directly bear vehicular loads and to contribute to the bridge structure's overall load-bearing behaviour. The orthotropic deck may be integral with or supported on a grid of deck framing members such as floor beams and girders.
The same is also true of the concrete slab in a composite girder bridge, but the steel orthotropic deck is considerably lighter, and therefore allows longer span bridges to be more efficiently designed.
The stiffening elements can serve several functions simultaneously. They enhance the bending resistance of the plate to allow it to carry local wheel loads and distribute those loads to main girders. They also increase the total cross-sectional area of steel in the plate, which can increase its contribution to the overall bending capacity of the deck (i.e. the deck plate acts as a top flange in a box or I beam girder). Finally, the stiffeners increase the resistance of the plate to buckling.
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