Sunday, August 13, 2017

Willamette River Crossings: Marion Street Bridge in Salem, Oregon

July 2017 (44.94556-123.04250) Marion Street Bridge
A hundred yards south of last week's Union Street Railway Bridge is the westbound Marion Street (I-22) Highway Bridge. This bridge is 2400 ft long and 56 ft wide with a steel plate girder superstructure. It was the longest plate girder bridge west of the Mississippi when it was built (in 1952).
The bridge's most unusual feature is that it's supported on pier walls having gothic arch openings. Gothic arch shapes were also used on the nearby Independence Bridge and in some of the arch bridges by Conde McCullough along the Oregon coast. The designer of the Marion Street Bridge, Glenn S. Paxson succeeded McCullough as Oregon's Chief Bridge Engineer and may have used the arches as a tribute to his old boss.
Before this bridge was built, all the traffic across the Willamette was carried on the adjacent Center Street Bridge. In fact, looking at the construction photo below (courtesy of the City of Salem), it appears that this bridge originally had only a single pier at each support (it was widened in the 1980s). That explains why the steel plate girders continue along the approaches on the original bridge but have been switched to concrete for the approaches of the widening (see photo above).
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