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Move that Bridge

AGC Member Shifts Span in 14 Hours

In January of this year, the Slayden/Sundt Joint Venture and Omega Morgan (both AGC Oregon-Columbia Chapter members), successfully moved Multnomah County’s 87-year-old Sellwood Bridge in Portland, Ore., onto new supports, creating a detour bridge that will carry approximately 30,000 motorists, bicyclists and pedestrians per day across the Willamette River until a replacement bridge opens in summer 2015. The undertaking –which was completed in 14 hours – was highly complex due to the age, shape and size of the truss, combined with the curved path of the move.

Here, in pictures, is the story of the Sellwood Bridge move.

A 1,100 linear-ft-long truss is moved from the existing piers to temporary bents built to allow the existing bridge to be used as a detour. The existing piers will be removed and the new bridge will be built on the original alignment.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

The 3,400-ton truss was one of the longest bridge parts ever moved, according to Multnomah County officials.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Skid beams – 14-ft-long ski-shaped steel units that slid on Teflon pads in the track beams – were used to shift the truss into position.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

The old approach to the truss (left) was demolished. On the right is the new approach built for the detour.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Since the truss moved twice the distance at the west end as it moved on the east end, each jack had to push an exact distance to ensure the 1,100 feet of truss moved uniformly.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Horizontal hydraulic jacks and tracks were used to move the truss.

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Photos courtesy of Anna M. Campbell, Image Engineering Photography