PORTLAND, Ore. — Construction is still a few years away, but once it starts, the Burnside Bridge will be closed for five years.
There's an open house Thursday, May 30, from 6 to 8pm in the county board room, and a virtual option can be seen online here on the county's You Tube channel.
Planning continues for Earthquake Ready Burnside Bridge, a replacement for the downtown Portland river crossing that will be built to withstand a major earthquake. The $895 million project has been flying mostly under the radar, but it got some visual movement last week.
People driving or walking across the bridge last week may have seen and heard a loud drilling operation down at the Waterfront Park below. Contractors were boring 200-foot-deep holes to take soil samples that will help determine the type of foundations that will support the new bridge — an important part of the still-in-progress design phase.
Built in 1926, the current Burnside Bridge carried about 35,000 vehicles across the Willamette River per day as of 2019. It was declared a "regional lifeline" in 1996 because Burnside is the most direct route from Gresham to Washington County, making it a critical pathway for emergency services in the aftermath of a disaster like a major earthquake.
"We have a one-in-three chance of a major Cascadia Subduction Zone earthquake hitting our region in the next 50 years," said Sarah Hurwitz with Multnomah County, which owns and operates the bridge.
But in order for that plan to work, the bridge has to survive the earthquake — and the current Burnside Bridge won't cut it. Like many of Portland's other downtown Willamette River bridges, it was built long before the region's earthquake risks were understood, and it's expected to collapse outright or be rendered unusable for a long time when The Big One hits.
"At this point in time in downtown Portland, there are no bridges that would be immediately useable in the wake of a major earthquake," Hurwitz said.
The county determined in 2016 that the Burnside Bridge was the highest priority and should be the first of Portland's downtown bridges to be replaced with a structure built to modern seismic standards. That decision set in motion years of meetings and planning that evolved into the current design process.
Some of the high-level design decisions have already been made; the new bridge will have four lanes for vehicles, with protected bike lanes and sidewalks on each side. The soil samples will help refine the design further, to "help our team build the safest and most structurally sound foundation for the bridge," Hurwitz said.
Other aspects of the design are still up in the air, such as the structure of the bridge's east end over Interstate 5. Options under discussion include a cable-stayed design that would resemble Tilikum Crossing or a tied-arch design, like the Wapato Bridge on Sauvie Island.
A new public survey will open up in late June to gather more feedback about some of the bridge design options, including aesthetic treatments.
"We want the community to weigh in," Hurwitz said. "The bridge has been around for nearly a hundred years, this is a really a historic moment when you think about it, this is the community’s bridge and we want its new construction to reflect that."
And while construction is still years away, it can't be stressed enough: it's going to be very disruptive. The current Burnside Bridge will need to be torn down to make room for the new structure, which means during the five years that the project is being built, those 35,000 cars per day will all have to scurry on to other downtown bridges.