Need for Replacement
In many ways, the design of the Sellwood Bridge was inadequate from the day it opened. Even for its time the bridge was narrow, having only two lanes, no shoulders or median, and one four foot sidewalk.
The narrowness of the Willamette River, which originally made the bridge location so attractive and cost-effective, was the result of an ancient and active landslide which is gradually pushing eastward from the West Hills. In the late 1950s the hill slid several feet toward the bridge, and in the 1960s it was necessary for the county to remove a 1½ foot section of the west side approach span in order to alleviate pressure on the structure. Diagonal supports were added to the west end of the bridge in 1961 to add rigidity to the structure as the movement of the land pushed the foundations towards the river. Over time, settling from ground movement has caused several of the bridge columns to twist, creating visible sagging in the bridge structure.
Since the Sellwood was the first Portland bridge not built to accommodate heavy streetcars, it lacks the sturdier design of other city bridges and has not been as able to accommodate the heavier weight of today’s heavy trucks and buses. In 2004, after years of heavy traffic loads, cracks were discovered in the concrete girders on the east and west approach spans. Vehicles weighing more than 10 tons have since been banned from using the bridge, and these weight limits have helped to slow the further growth of cracks in the structure.
The New Sellwood Bridge
Work to replace the Sellwood began in 2006 as a planning effort to develop a community-supported solution to address the long-term transportation deficiencies posed by the deterioration of the bridge. As part of this work, Multnomah County prepared an Environmental Impact Statement (EIS) that summarized major environmental impacts, community concerns and considered alternative solutions.
A preferred alternative was selected in 2009, calling for a new bridge to be built on the same alignment. The new bridge would be 64-feet wide at its narrowest point, with two 12-foot travel lanes, two 12-foot shared use sidewalks, and two 6.5-foot bike lanes/emergency shoulders.
At their January 27, 2011 meeting, the Multnomah Board of County Commissioners agreed with the recommendation of the project committees and approved a steel deck arch bridge type for the replacement Sellwood Bridge.
The bridge is being designed by T.Y. Lin International (San Francisco) and built by Slayden/Sundt, a joint venture of Slayden Construction Group (Stayton, Oregon) and Sundt Construction (Tempe, Arizona).
Work on the new bridge began in summer 2012 . The main truss spans of the original Sellwood Bridge will continue to see service as part of a detour bridge set on new piers during the construction of the replacement bridge. When the new bridge is opened, the old Sellwood Bridge will be made available for re-use at a different location. If the bridge is not relocated, its steel and concrete will be recycled, continuing the cycle of re-use that started when parts of the old Burnside Bridge were used to build the Sellwood Bridge in 1925.