Name that shape: Inverted-Y design approved for Burnside Bridge replacement

The Multnomah County Board of Commissioners approved a new look for the Burnside Bridge on Thursday, marking a historic milestone as officials prepare to earthquake-proof the structure.

Building the inverted-Y designed bridge is anticipated to cost more than $900 million and will require the bridge to close for five years.

In a unanimous vote, commissioners voted for the triangular, cable-stay design which features a single tower supported by two legs.

“This is an iconic, long-lasting decision for our community and a major milestone for this critical project,” Chair Jessica Vega Pederson said in a statement. “I want to thank the overwhelming number of people who’ve joined this process and helped us take this next important step. Portland is shaped by our bridges and your energy met this moment.”

At 17 feet, the new Burnside Bridge boasts the largest bike and pedestrian space of all downtown Portland bridges, and the event of an earthquake, the bridge will help connect the east and west sides.

Commissioner Lori Stegmann said deciding on a safe, sustainable bridge design was a critical choice for the board, which was a sentiment Commissioner Sharon Meieran echoed.

“Like Commissioner Stegmann, I look at bridges everywhere I go,” Meieran said. “They stand out, they do mean something. This bridge project has spanned my career on the board and I am proud of the result.”

How were decisions made?

Earlier this summer, the project launched an online survey in efforts to reach the community for input.

A handful of options were on the table: three cable-stay and three tied-arch options of various sizes.

Ahead of the survey, which closed on July 31, the public could watch 3D videos and use interactive graphics to better make sense of what it could feel like being on or near the bridge.

Several events were hosted by the county during the input period to encourage community engagement. Team members and community representatives held live panel discussions, and they had devices on stand-by for anyone looking to take the survey on-site.

Once the survey closed, the project team provided insights to Community Design Advisory Group on the public's response.

Who's the Community Design Advisory Group?

Throughout the last year, the group comprised of 20 community members has worked with the project team to identify several bridge type options for the east side of the bridge.

The Community Design Advisory Group gives ideas on bridge aesthetics such as colors, materials and lighting, as well as the shape of features on the bridge.

One of the group's key responsibilities was to provide a bridge type recommendation to the project team.

Once the public's opinion was heard, along with the project architect's bridge type preference, multiple meetings were held through the month of August to which the group voted to recommend the inverted-Y design.

“This is a historic moment for the project,” Jon Henrichsen, transportation division director, said in a statement. “For the first time, we know what we’re going to design and build for each part of the bridge — from downtown, across the river and for the east long span. We know its mark on the Portland skyline and now we can continue working toward our 30% design milestone by October.”

So, where did all of this start?

In 2016, the Earthquake Ready Burnside Bridge project began with a two-year Feasibility Study Phase from 2017-19, where the project team studied more than 100 options including tunnels, ferries, double-deck bridges and more.

From that study, four bridge alternatives were recommended for further evaluation during the four-year Environmental Review Phase from 2019-23.

The Replacement Long-Span was selected as the Preferred Alternative after an environmental analysis of the four alternative along with input form the community, agencies and regulatory bodies.

In the fall of last year, Multnomah County entered the design phase. Before advancing any of the six options, the county considered input from the community and architects.

As of now, it is likely that none of Portland's Willamette River vehicular bridges will be immediately usable after a major earthquake. The replacement of the Burnside Bridge is currently one of the largest earthquake resilience projects in Oregon.

For more information on the project visit multco.us/earthquake-ready-burnside-bridge .