Aging Bridge is Moved Aside to Make Way for New Structure

 |  Civil & Transportation
The 1,100-foot-long steel bridge truss was moved last Saturday during a 12-hour operation. It is approximately 25 feet high, weighs about 3,400 tons and had to be moved 33 feet on one end and 66 feet on the other.

If you were anywhere near the Sellwood Bridge in Portland, Ore., last Saturday, you would have seen an amazing sight. A 1,100-foot-section of the existing bridge deck and truss was lifted with hydraulic jacks, moved aside and set onto temporary support piers to make way for construction of a new bridge. The move created what is known as a “shoofly,” or detour bridge, which will keep traffic flowing over the Willamette River as crews build the new structure to take its place.

Reconstruction of the 87-year-old Sellwood Bridge is being performed by Sundt and joint venture partner Slayden Construction. The team’s innovative approach to the project is expected to save about $5 to $10 million in construction costs and cut about a year off the schedule.

Bridge construction is notoriously challenging, but even so, last Saturday’s “bridge slide” was considered a highly complex operation.

“This was one of the longest bridge sections ever to be moved,” said Sundt Area Manager Ted Aadland.  “That, plus its age, made it very difficult. The site itself also presents a number of challenges. The project is tightly confined, being sandwiched between the Willamette River, a cemetery and difficult topography. The Slayden/Sundt Joint Venture Team has worked hard to come up with solutions that minimize traffic impacts, and so far I think we’ve been very successful.”