Light load: Bridge relocation

by MM&D staff

PORTLAND, Oregon—As fixed, stationary, permanent installations, bridges are designed to facilitate traffic moving across them. Bridges themselves, however, aren’t supposed move from one physical location to another. But that’s what’s happening this weekend in Portland, Oregon.

The bridge in question is the Sellwood Bridge, which spans the Willamette River. It is 335m (1,100ft) long, 23m (75ft) high, 8.5m (28ft) wide and accommodates 30,500 vehicles every day. But the 87-year-old piece of infrastructure needs to be replaced. So a new link is being built across the river at a cost of over $300 million. Construction on the new bridge is expected to be completed in 2016.

There are two catches, however, with the construction project. The first is the new bridge needs to be constructed in the same location as the old one. The second is traffic still needs to find a way to move from one side of the river to the other, which means the Sellwood Bridge, simply can’t be torn down.

The solution being attempted is to move the old bridge to a new location, reconnect it to the road network, and reroute vehicles over the relocated span while construction is underway.

The company in charge of the move is Omega Morgan, a local Portland business that specializes in large-scale moving operations.

“Omega Morgan has moved bridges weighing upwards of eight million pounds, but this one does offer some additional challenges,” Omega Morgan president and CEO John McCalla.

According to the company, the relocation plan “is to use hydraulic jacks to lift the bridge onto skid gear and then to move and mount it on new piers that have been built in the river”.

After it is moved the bridge will “shoofly” (or detour) the traffic being diverted away from the construction project. That is, after it has passed a safety inspection.

The move is scheduled to begin on January 19, 2013. To watch it live, click here.

UPDATE: To see a time-lapsed video of the move click here.