Bridge move wows Portlanders

The green steel truss span of Sellwood Bridge, shown in the 2010 photo, was moved to new supports to clear the way for a replacement bridge. (Photo: Steve Morgan, Wikimedia)
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Trish Anderton

Engineering crews moved the 3400-ton Sellwood Bridge more than 30 feet in Portland, Oregon on Saturday. The project not only completed a key step in replacing the aging structure – it inspired an impromptu daylong festival among local residents who turned out to watch. 

As OregonLive reported, “hundreds of awestruck onlookers” gathered to gawk as workers using 50 hydraulic jacks slid the bridge's truss span on specially-constructed tracks until it rested on a new set of supports. Since the span is a continuous piece of steel, rather than a series of segments, it was not possible to move it in pieces. An impressive time-lapse video shows the steel span sliding a few inches at a time.

The old bridge will remain in use while its replacement is built alongside it, which should take until the summer of 2015.

And it won’t be a moment too soon. As the news site noted, the bridge over the Willamette River rates “a miserable two” on a federal bridge-safety scale of 0 to 100. When the concrete in its east and west approaches cracked in 2004, officials lowered the maximum weight of vehicles allowed on the bridge from 32 tons to 10 tons.

The old bridge is also narrow, with no shoulders and only a four-foot sidewalk. The new one will have two shoulders and two 12-foot sidewalks.

Portlanders tweeted enthusiastically about the project.

“The @SellwoodBridge Move was pretty amazing!” wrote @bentonmcleod. “They moved an 87-yr-old, 1100-ft bridge. Seriously.”

“The moving of the Sellwood bridge is cool on many levels. Shout out to all involved. Pretty smart group of people,” @mschofer agreed.

“A great day with tons of neighbors watching the Sellwood Bridge move,” tweeted @TildeShop, a local art gallery.

A few wondered if the old span would still be safe to use, though.

“I'm no engineer, but the Sellwood Br. seems more dangerous than ever,” mused @cherrytree503.

According to the project website, the bridge is expected to be stronger in its new, temporary location. That’s because a damaged approach section has been replaced and the span is sitting on new supports.

Some $34 million of the project’s $299 million price tag is coming from the federal government. That includes a $17.7 million Transportation Investments Generating Economic Recovery (TIGER) grant from the U.S. Department of Transportation that provided the final infusion of cash necessary to launch the project. State and local governments will foot the remainder of the bill. A hike in local vehicle registration fees is the project’s single largest funding source.

As GIMBY's News Focus recently reported, aging bridges are an increasingly urgent problem in the U.S. Nearly 70,000 bridges nationwide are considered structurally deficient; a 2011 report from the nonprofit group Transportation for America predicted that almost half of the nation’s 600,000 bridges will need "major structural investments within the next 15 years." Federal officials hope innovative approaches - like the one used for the Sellwood Bridge - will make it faster and easier to repair and replace old spans.