Yes, the Burnside Bridge is (Most Likely) Toast

 

Multnomah County Images of a Potential New Bridge 

Members of two civic commissions that will review the looks of a new Burnside Bridge wondered if the existing historic bridge could be braced adequately against the rumblings of a major earthquake.  They got their answer on Jan. 25.

 In a word, nope.   Members of the Portland Landmarks Commission and the Portland Design Commission easily reached an informal consensus after a joint briefing where one of the chief bridge planners laid out numerous difficulties in trying to revamp the existing bridge built in 1926.

 “It’s a question that has come up quite a bit,” said Steve Drahota,  a consultant with the HDR engineering and planning firm that is a member of the Multnomah County bridge planning team.

 “I’m a bridge designer,” he said.  “I love the Burnside Bridge.”  Nevertheless, it was built in an era when engineers knew nothing about seismic bracing or the risk of a major quake in Portland.  The Burnside route with its through-routes to East Portland and West Portland has been chosen by regional planners to be the key bridge link needing to survive a severe Cascadian subduction zone earthquake.

From its telephone-pole pilings under the river to its deck, railings, bascule mechanisms, cute operator’s houses and supporting columns on both sides of the river, “There is no piece of the bridge we wouldn’t have to touch in some way,” Drahota said.

Perhaps the biggest challenge would be supporting columns at the east end of the bridge, where mushy, unstable soils reach as much as 200 feet below the surface.  This are the soils that are subject to liquefaction in a major quake, which Drahota said amounts to the wet mass turning to Jell-O or soup.  The better solution, he said, is a “long span” option in which most of the unstable soil would be avoided.

John Czarnecki, an architect and long-time preservation advocate, told the two commissions that he thought the analysis was one-sided against reinforcing the old bridge.  “We seem to be looking at reasons to destroy the bridge,” he said.

 Members of the two commissions, however, clearly were impressed by Drahota’s presentation.  A design commissioner, Zari Santner, said the presentation “addressed everything we raised that needed to be clarified.”  A landmarks commissioner, Andrew Smith, said trying to retrofit the old bridge would lead to a “Burnside Frankenstein and it still wouldn’t perform as it should.”

 Matthew Roman said he was no longer concerned about trying to save the bridge.  “I’m convinced from the presentation today that it’s not feasible.”

 Maya Foty, a landmarks commissioner, said the city needs to turn its attention to building an attractive bridge, even if it costs more money.  “Wouldn’t it be exciting to have a bridge people want to come to see?”  She mentioned the Sundial Bridge in Redding, California, as an example.

The proposed long-span new bridge would be about 20 feet wider than the current bridge, once it departs from the street grid.  The extra width would allow for wider vehicular lanes by about six inches each, and wider bicycle and pedestrian routes.

At Czarnecki's request, the Architectural Heritage Center has created a small committee to see if bridge rehabilitation options have been adequately considered.  If the bridge is to be demolished, the committee will offer suggestions on saving or commemorating the bridge's historical elements.

Steve Dotterrer, AHC  advocacy committee chair, said defeat of last November's regional transportation ballot measure could slow planning and construction timelines. 

There are many procedural hoops to clear as bridge planning continues.  At present, the start of a final design is expected in 2022, and construction is expected to last from 2024 to 2028.