Multnomah County turned a 1925-built bridge serving as a traffic pinch-point into an award-winning new design when it created a fresh Sellwood Bridge across the Willamette River. Now that bridge has earned the highest marks of any entry to date in the Greenroads Project certification process.
The Sellwood Bridge, part of a $324 million Sellwood Bridge Replacement program in Portland took a structurally deficient, seismically vulnerable and traffic-limiting bridge and created a new crossing that allows for a wide range of transportation modes.
"One of our goals for the project was to reflect the county's values around sustainability, and we feel that the Greenroads certification is independent recognition that the county has achieved those goals," says Ian Cannon, transportation director and county engineer for Multnomah County.
With a design from T.Y. Lin, CH2M Hill and David Evans Associates with contractor Slayden Sundt Joint Venture, the crossing now has a list of features the Greenroads Foundation applauds, such as 12-ft sidewalks and 6.5-ft bike lanes on each side of the bridge, new routes for transit as buses were prohibited on the former bridge, dark-sky friendly luminaries with energy-efficient LEDs, lookout points with educational signage and 94 percent of construction materials (by cost) sourced within 50 miles. The new bridge also features a stronger connection into the trail network on both ends of the bridge to better tie to routes that those not using cars travel.
"What sets this project apart is how much collaboration happened between Multnomah County, Oregon Department of Transportation, the City of Portland and the design and construction teams,” says Jeralee Anderson, CEO of Greenroads Foundation. “That collaboration was key to achieving so many environmental, social, and economic wins for this green bridge."
Using the construction manager/general contractor approach brought together multiple disciplines of the project delivery team before construction started to allow them to devise value-added solutions. The most noticeable was a lateral bridge slide, which moved the old bridge off its current site to make space for the new bridge but allow room for the construction of the new replacement bridge while maintaining existing traffic connections. The shift also allowed the project to circumvent and reduce environmental impacts within the waterway by avoiding building the new bridge in two phases, each requiring in-water work.
Greenroads says the consultants and construction teams also made responsible choices in the design of the bridge section and material sourcing.
Portland being known for its signature crossings meant that a new Sellwood Bridge needed to fit the aesthetical of both the neighborhood and the city. The resulting design was a steel deck arch made with recycled components that echoes the character of the first bridge.
Established in 2010, the Greenroads Foundation is a nonprofit corporation advancing sustainability education and initiatives for transportation infrastructure. There are currently more than 120 projects registered for the Greendroads Project Rating Program in 11 states and eight countries.
Follow Tim Newcomb on Twitter at @tdnewcomb.