Sunday, September 10, 2017

Willamette River Crossings: Sellwood Bridge in Portland, Oregon

July 2017 (45.46441, -122.66461) Sellwood Bridge
The last bridge I photographed over the Willamette River was the Sellwood Bridge, which opened in 2017. It's a 1,976 ft long bridge with three steel arch spans over the river. It was designed by T. Y. Lin International, who also designed last week's Tilikum Crossing.
The new bridge replaced a deck truss structure that was designed by Gustav Lindenthal in 1925. The contractor (Slayden/Sundt Joint Venture) moved the old superstructure from its concrete piers onto temporary steel towers so people could use it while the new bridge was being built (see photo below courtesy of KATU).
An interesting detail on the new bridge is the concrete arch springings that project out of the caissons and connect to the steel arch ribs (see photo below). The deck is supported by the spandrel columns on the arches and by big steel piers directly over the caissons.
The concrete springings are repeated at the ends of the river spans where they are buried deep into the ground to resist service loads and the occasion earthquake (see photo below).
The new bridge has a 63' to 93' wide deck with two vehicle lanes, two 6.5 ft wide shoulder/bike lanes, and two 12 foot wide sidewalks. There is also a middle lane to allow for future light rail tracks (see photo below). The bridge  owner is Multnomah County.
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