Multnomah County's Mike Pullen and PSU students' site visit (NashCO Photography)
BY BRIAN LIBBY
Four years ago, a Pulitzer Prize-winning New Yorker magazine article by Kathryn Schulz awakened many in the Pacific Northwest for the first time to the fact that a massive earthquake could someday destroy our cities and towns. I particularly remember one seismologist saying everything west of Interstate 5 would be "toast."
Over the ensuing four years, Portland has made very modest progress in preparing for what could be a 9.0 reading on the Richter Scale. But one emerging priority that we might get some, well, traction on is the Burnside Bridge, which has long been identified as a priority east-west emergency route in the event of a seismic catastrophe. Interstate 5 and Interstate 84 would probably be incapacitated by collapsed overpass bridges, making Burnside Street and Sandy Boulevard the most likely routes for emergency vehicles and supplies.
Each day about 40,000 vehicles cross the bridge as well as 2,000 pedestrians and bicyclists. The bridge also passes over not only the I-5 freeway but the Union Pacific railroad and a MAX line on the downtown side. Burnside Street itself is also the one street in the city that touches the Southeast, Southwest and Northeast quadrants. But the Burnside Bridge is not strong enough to survive a major earthquake. Completed in 1926, its concrete columns include very little steel reinforcement. Weak unstable soil can cause its piers to collapse, a cracking of the pier and collapsing of the draw spans, falling into the river and blocking ship passage.
Stills from the video Earthquake Ready Burnside Bridge: Simulation (Multnomah County)
It's time to start thinking about a new Burnside Bridge. It's not yet a done deal that Multnomah County is willing to take that step. But they have decided to do something, whether reinforce the old bridge or build a new one. To that end, the county has been exploring its options and, after exploring about 100 different options, has settled on four: a renovation of the 1926 bridge, a fixed bridge that arcs high enough to allow river traffic to pass underneath, a drawbridge in the same configuration as exists now, and a drawbridge with a new access point from Couch Street.
One reason that it's statistically only a one-in-four chance that the 1926 bridge will be renovated is that it's only about 10 percent cheaper to do so than it would be to build an entirely new bridge. "So much has to be replaced," explains Multnomah County spokesperson Mike Pullen. "If the purpose of the project is not only renovation but seismic strengthening, you have to go deep underground under every column. There must be 15 spans just between the river and where that comes down. Each one of those columns has to have big seismic foundations put underneath. So new bridges are really on the table."
It's also quite unlikely at this point that a new bridge would be fixed. I mean, have you ever tried to walk or bike over Tilikum Crossing? It's climbing a small hill. And at this spot, such a bridge probably wouldn't work. "It’s looking like the fixed bridge would need to be so high because of the rose fleet and a few cruise ships that it would exceed what’s reasonable," Pullen explained. "It’s not in the grave yet, but it may have the most problems to eliminate it from contention." A fixed bridge also needs more of a lead-in from the blocks on either side, which would further disrupt the existing city fabric.
Pullen says the Hawthorne Bridge remains the most popular bridge for pedestrian and bike crossings because it's the opposite of a bridge like Tilikum, not just in that it's a drawbridge instead of a fixed bridge but because it's the most even with the existing street. But the existing Burnside Bridge has this same flatness. It just feels less intimate because it's wider for cars and thinner for pedestrians and bikes.
Aside from the question of a fixed bridge or a movable bridge, at this stage, Multnomah County has not decided on a bridge type. If we build a new movable Burnside Bridge, it could be a bascule bridge like the existing Burnside or Morrison Bridge, where the two leaves tilt upward to let ships pass. Or it could be a vertical-lift bridge like the Hawthorne or the Steel Bridge. Those are among the oldest bridges in Portland, but there are examples of contemporary vertical-lift bridges, such as the Pont Jacques Chaban-Delmas in Bordeaux, France, completed in 2013 and designed by Lavigne & Cheron architects and Hardesty & Hanover. When I look at photos of that bridge and imagine a future Burnside Bridge that looks something like that, I get excited. But there are also great examples of contemporary bascule bridges out there.
Pont Jacques Chaban-Delmas bridge, Bordeaux (Wikimedia Commons)
All these questions about a potential new Burnside Bridge came up recently because of an open house held May 15 at Portland State University's School of Architecture in Shattuck Hall, where master of architecture students in professor Jeff Schnabel's class presented the results of their studio class projects devoted to Burnside Bridge designs.
Bridges really acts of engineering more than they are works of architecture, which meant that engineers from Multnomah County worked with the students to impose real-world constraints, something not always part of architecture school projects.
"There were many moments where the engineers would say, ‘That’s an interesting idea but it doesn’t work. Here’s why.’ In a traditional studio you’ve got quite a bit of room to be visionary without constraints," Schnabel explains. "Here, the county did impose some meaningful constraints. The students found that to be rewarding and at times frustrating. If they were choosing between a bascule or vertical lift bridge, they had to make sure they passed the eye test in terms of operation. If they were driving too many piers down into the river, the county would push back and say, ‘That’s a cost issue. The more you touch down, the more expensive it becomes.’ But those are the kinds of things that made the projects very real to the students."
Having real constraints meant that a good design idea within them meant that the county could take it seriously. "That may have been the case with one student project, which featured stairs going from the bridge down to a dock. "Before the earthquake it’s an amenity, an opportunity to get down to the river," Schnabel says. "Post-earthquake, they could see the value of that as part of a water taxi system that could assist in the evacuation of pedestrians from the city or the delivery of goods and service workers to downtown, taking some of the pressure off the surface of the bridge."
Overall, Pullen says, a major theme in student designs was figuring out to separate bicyclists and pedestrians from other motorists, "sometimes on a different level, sometimes in a kind of tube. One we almost nicknamed the Spanish Steps. It’s not just a staircase. It’s almost a block wide and it becomes an amphitheater at the bottom. I know that might bust the budget, but a connection between the pedestrians and Waterfront Park is a great idea. Thinking about ways to increase connections and connectivity is huge. Right now from both the Morrison and the Burnside you can’t get directly into waterfront park. The Hawthorne has stairs and that’s not the greatest option either."
A presentation by PSU student Rebecca Taylor (NashCO Photography)
I also enjoyed one other proposal, even if it's extremely unlikely. "One student looked at the buildings on the west side with all this unreinforced masonry, and envisioned this kind of scaffolding system that tied the buildings to the bridge," Pullen recalls. "The scaffolding created some covered areas down below that created gathering spaces. From a historic preservation standpoint, that might be hard to permit. But maybe there could be something done to make sure they don’t collapse."
Thinking about these options also made me wonder what form the process for designing a future Burnside Bridge might take. Would it be unrealistic, for instance, to suggest a design competition? After all, Multnomah County saw the value in connecting with students. Why not put out a call to some of the world's best bridge designers? After all, it certainly worked well for one of the city's last major infrastructure projects: the Portland Aerial Tram. But this is a county project, not a city one. And Multnomah County has a different personality and tendencies than the City of Portland. The new Multnomah County Courthouse, currently under construction downtown at the west end of the Hawthorne Bridge is a good example. Designed by Portland firm SRG Partnership, it figures to be a handsome building. But during the first round of selection for the courthouse, Multnomah County decided not to shortlist two of the top architecture firms in the world: the Office for Metropolitan Architecture (headed by Pritzker Prize winner Rem Koolhaas) and Skidmore, Owings and Merrill. It's one thing if they selected an SRG design over an OMA or SOM design. They're all just different three-letter acronyms, right? But not to shortlist these great firms—to write into the process an explicit preference for local firms—raised a red flag of what I'd call deliberate provincialism, at least for me.
A client that won't even consider the world's top firms for a riverfront courthouse doesn't sound like a client that will create an exemplary international design competition.
That said, the two projects are different, even if the client is the same. "I think it’s fair to say the county was happy that [for the courthouse project] the architect and the general contractor were local…I think when it comes to bridge projects, I’m not sure the rules allow that kind of preference." And besides, Pullen makes a reasonable follow-up point. If you look at a county project like the Sellwood Bridge, there are reasons to believe quality was as important as budget. "We have gotten away from low-bid in that we do a CMGC model. So basically you can veer from the low-bid, traditional contracting model, if you build a case and go to the state," he says. "If we can make a case that the project is either of such complexity, specialized skills, we’re able to make a case for a different project delivery model. In the case of the Sellwood project, we were able to hire a team based on skills in addition to price. We ended up there with TY Lin International on the lead with the bridge design. They’re probably one of the top bridge designers in the world and win a number of awards."
It has been four years since Tilikum Crossing opened and five years since the replacement Sellwood Bridge. Before that, though, several decades went by between our last bridge project, the Fremont Bridge, and the recent Sellwood redo. To put it another way, replacing one of our most prominent and central downtown bridges would be a major change to Portland's postcard image of itself. We are as much Bridge City as we are the Rose City or Stumptown. And the Burnside is more center-stage than Tilikum or Sellwood.
A design first has to work: to be functional for a variety of pedestrians, bicyclists and automobiles and to be well connected to the existing urban fabric, as well as the resilience to survive the Really Big One. That last one is the whole point. And Portland is not the sort of city that has the ambition, the financial willingness or the insecurity to invest in a showy design. Yet no matter what we build, it will have an aesthetic personality of some sort, and that should not be shortchanged any more than safety and function.
Bridges represent a unique opportunity. On one hand, they possess an aspect of humility because they are connectors: the places between places. Yet from the Golden Gate Bridge to the Tower Bridge, they inevitably become symbols. Free from the clutter of buildings or topography getting in the way, they stand proudly even when they are essentially flat.
I sometimes think of an idea credited to philosopher Martin Heidegger. In Building Dwelling Thinking, he argues that a bridge does not just connect banks that are already there. "The banks emerge as banks only only as the bridge crosses the stream," Heidigger writes. "The bridge gathers the earth as landscape around the stream."
In other words, a bridge is a connector, but it is also a distinct place.
Advertisements
Comments