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A tunnel under the Willamette River is still an option on the table for replacing the aging and vulnerable Burnside Bridge.

The alternative was discussed last week at a coffee-and-pizza stakeholders meeting facilitated by the agency in charge of the 91-year-old span, Multnomah County.

Officials are considering how to shore up the 17-mile 鈥�Burnside Corridor鈥� 鈥� Burnside Street from U.S. Route 26 to Gresham 鈥� as a 鈥渓ifeline鈥� through the Portland-metro area, with the bridge over the Willamette River an acknowledged weak link.

A tunnel, however, is considered a highly unlikely solution, for reasons including high energy consumption and lack of space for terminals. What’s looking more and more likely is that all or parts of the Burnside Bridge will need to be replaced to provide a regional lifeline in the case of a major seismic event.

Other options that fared poorly in the assessment by the county’s consultants include preserving the Burnside Bridge, performing a full retrofit, and bolstering a different bridge, such as the Morrison. Though these alternatives scored low, planners cautioned nothing has been decided yet.

The county’s project manager, Megan Neill, said the 鈥渦niverse of options鈥� for a Burnside Bridge upgrade is expected to be reduced enough by next fall for a recommendation to be presented to the Board of County Commissioners. After approval, around a decade could pass before project completion.

The meeting of stakeholders was the second of four. Interested parties have included the Old Town Chinatown Community Association, the Central Eastside Industrial Council, the Portland Saturday Market and Burnside Skatepark users. Wide-ranging discussions at this meeting and previous ones have covered how Portland will respond to a Cascadia Subduction Zone earthquake 鈥� specifically, how it will clear debris and kick-start commerce.

The project is one of several efforts by governments in the region to prepare for fallout of a major quake. Metro is drafting a debris management plan, and the Portland Bureau of Transportation is preparing a plan for transportation recovery and a plan for upgrading unreinforced masonry buildings.

Dan Yates, director of the Portland Spirit, said his business signed an agreement with the city years ago to provide ferry service across the Willamette River in case of a major disaster.

He and others mused at the meeting about how Portlanders would respond when tested by disaster.

鈥淚 bet this city surprises itself,鈥� he said. 鈥淧eople will do remarkable things after a big event.鈥�

None of inner Portland’s bridges are expected to fare well in a major earthquake. Even TriMet‘s young Tilikum Crossing is compromised by highly liquefiable soil beneath its approaches. The county’s two most recent large bridge replacements, the Sauvie Island Bridge ($48 million) and the Sellwood Bridge ($215 million), both meet current seismic code, but the crossings aren’t considered good seismic lifelines due to their locations and other factors.

鈥淚t’s really a call to action,鈥� Neill said. 鈥淧eople wonder why we’re focusing on a bridge in Portland, but we feel it’s important to the entire region to restore service to the Burnside.鈥�

Like the Tilikum Crossing, the soils under the Burnside Bridge are highly liquefiable and expected at the east approach to move toward the river more than 20 feet. This will have to be addressed in whichever plan is adopted.

One space likely to be significantly affected is the Burnside Skatepark, which was constructed off-the-books in the 1990s among the bridge abutments on the bridge’s east side.

鈥淚t feels to me that there are going to be some kind of impacts to the skate park no matter what alternative we talk about,鈥� said Jeff Heilman of consultancy Parametrix. 鈥淭here are certainly needs in those existing columns.鈥�

The skate park’s designated representative was not in attendance Thursday.

Stakeholders at the meeting acknowledged another major challenge: informing constituents. The county recently scored a win in this regard. It paid $135,000 to engineering firm HDR to create a realistic video rendering of the bridge during an earthquake. It’s so far gotten more than 50,000 views.

(Editor’s note: This story has been modified from an original version to reflect the correct price for a video rendering of the Burnside Bridge during an earthquake.)