Multnomah County leaders want residents to see a new simulation that shows what would happen to the Burnside Bridge if an expected magnitude 9.0 Cascadia Subduction Zone earthquake hit the area.
The video shows the concrete pillars under the bridge, which would be expected to fail first, swaying and then collapsing. Over the next several moments, the rest of the bridge effectively crumbles onto Naito Parkway, into the Willamette River, and onto Interstate 5 and Interstate 84 on the east end of the span.
The locks that bind the drawbridge spans together would come undone, sending those sections waving into the air before falling into the water, blocking bridge traffic.
It’s a terrifying scenario.
“This was the product of a lot of engineering and thinking in what went into that video,” county spokesperson Mike Pullen explained. “So it’s not just Hollywood, it’s really the best guess of our engineers of what would happen.”
Making matters worse, the 91-year-old bridge isn’t the only one expected to crumble.
“Believe me, it’s not just the Burnside Bridge that wouldn’t do well,” Pullen added. “In our whole downtown area, basically the new Tilikum Crossing Bridge is built to the Cascadia Zone standards and the new Sellwood Bridge, but all the other bridges are not going to be open the day after the earthquake.”
The good news is that Multnomah County plans to do something about that.
County officials want to focus on making the Burnside one bridge that would stand up to a major Cascadia earthquake, but that will involve upgrading the existing span or building a new bridge in its entirety.
It’s a process that will take a lot of time and money, and county leaders estimate work won’t be finished for five to eight years at the absolute earliest.
They are asking for the public’s input via an online survey in hopes of identifying concerns relating to the bridge and options for a safer crossing.
The Burnside Bridge was chosen because it’s a central route along a major street linking communities on both sides of the river from Washington County to Gresham.
The hope is it could be one reliable route for emergency responders, people, traffic and goods in the event of a major emergency across the Portland area.
Copyright 2017 KPTV-KPDX Broadcasting Corporation. All rights reserved.