|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.
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.
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.
Why can't the operator's houses be incorporated into a new bridge?ReplyDelete
Agree...good idea. However, they need to be seismically reinforced somehow. They are the equivalent of unreinforced masonry as they st stand.ReplyDelete
Why not rebuild the Burnside Bridge in the same style of the existing Burnside Bridge but with all the seismic requirements? The three proposals throw away all what the Burnside Bridge is. The bascule span and the below deck trusses together with the operator's houses and open deck all say Burnside Bridge. The three proposals, especially the cable supported idea, completely miss the mark of preserving the spirit of place the current bridge expresses so well.ReplyDelete
The difficulty with below-deck trusses arises mostly at the east end of the bridge, where there is an ostensible need to avoid the squishy soils. Those trusses have to connect to something in the ground. That is why the closed arches or the cable-supported concepts make more sense...if you believe in the beginning premise.ReplyDelete