Think Out Loud

New research focuses on resilience of Oregon’s coastal roads and bridges

By Julie Sabatier (OPB)
Aug. 10, 2022 10:21 p.m. Updated: Aug. 17, 2022 3:20 p.m.

Broadcast: Thursday, Aug. 11

Seaside is hoping to pass a $100 million bond to get it's schools out of the tsunami zone.

A sign in Seaside, Oregon points the way to the tsunami evacuation route.

Michael Clapp / OPB


Researchers at Oregon State University used computer modeling to assess the resilience of roads and bridges on the Oregon coast and how this critical infrastructure would fare in the event of a Cascadia Subduction Zone earthquake. A recently published study focuses on local roads as well as transportation infrastructure like highways that connect communities to each other. The researchers looked at how different factors would impact recovery on the entire coast from Warrenton to Gold Beach. OSU Civil and Construction Engineering Professor Dan Cox was one of the co-authors of the study. He joins us to dig into the details.

Note: The following transcript was computer generated and edited by a volunteer.

Dave Miller: This is Think Out Loud on OPB. I’m Dave Miller. What is going to happen along the full length of the Oregon coast from Brookings up to Astoria when the big one hits? How long will these communities be cut off from themselves and each other after the Cascadia Subduction Zone earthquake? Researchers at Oregon State University used computer modeling to answer these questions. They published their findings recently in the Journal of Infrastructure Systems. Dan Cox is one of the co-authors of the study. He is a professor of Civil and Construction Engineering at OSU. He joins us to talk about this work. Welcome to the show.

Dan Cox: Thank you for having me.

Miller: What specifically did you set out to answer with this study?

Cox: We set out to answer some of the questions that the communities were having about islanding. So that the study actually started with a bunch of listening sessions out on the Oregon Coast and the word islanding or disconnected came up a lot. And so we said, okay let’s put our best efforts there and figure out well, what are they, what do they want to be connected to? Is it being connected to each other, being connected to resources, to the valley? And the answer was yes, they wanted to be connected to everything. So we kind of set up our study to look at those different aspects of being connected.

Miller: What exactly does islanding mean?

Cox: There’s a lot of different aspects to it, from a social context, from a let’s say infrastructure/engineering context, and we kind of chose the latter in terms of like, how long will it take people to get from one location to another by, by car primarily, so along the highways, thinking about highways and bridges mostly.

Miller: So in a sense the key infrastructure questions here were, if these roads or these bridges go out and communities are cut off either internally or from the outside world, what happens and how long will it take for them to be connected again?

Cox: Exactly. How long will it take? And are there positive steps that we could take to make them get connected more quickly? So that was the last part of the study, were some of these different scenarios that might help the communities.

Miller: But for the first part, for the ‘how long will it take’? What did you find? I imagine there was a range, but can you give us a sense for how long people in Brookings or Newport or wherever can expect to be cut off and I should point out, if I’m not mistaken, what you were looking into, this was, the modeling was based on a really big one, a 9.0 earthquake. So how long can people in these communities be expected or should they expect to be cut off?

Cox: Yeah, that’s a great question, because what would be cut off, for example, is it search and rescue, is it repair vehicles or is it just people being able to use their own cars to access different parts of the coast and getting into the valley. We looked primarily at cars, thinking about the average person and what it would take for them to get back and forth. And for our study, we were looking at months to even years to get to full recovery.

Miller: Even just, I shouldn’t say even just, that’s for people in their own private vehicles, say to drive from the coast to the mid-valley, to Salem?

Cox: That’s a great question. It wasn’t just, it was more to get back to the way things were. So if it used to take 45 minutes to get there, how long will it take until it’s still back to a 45 minute drive? But there were other routes that people could take, it just took them longer to get from A to B. And so we kind of factored that into this study. So it’s kind of like, how long does it take to get back to normal? Not necessarily can they get there at all.


Miller: And the timeline was not days or weeks, but months or years?

Cox: To get back to normal, yeah.

Miller: One of the aspects of the Cascadia Subduction Zone earthquake scenarios that has always been hardest for me to wrap my head around is just how big an area we’re talking about, because the destruction could be from British Columbia all the way down to California and different places would be affected differently, but it’s just a, it’s a gigantic area and then it also obviously, obviously it goes east to bigger population centers. Does that basically mean that these communities would be on their own for long periods of time, because the help just can’t go to everywhere at once?

Cox: I think that’s a good point, because of the magnitude of this event, resources are going to be stretched very thin. That’s for sure and I think the point of our study was to look at these regional differences. So for example on the north coast versus the central coast and south coast. So we really wanted to look coastwide with this study, what communities are going to be affected and in what way.

Miller: What made the difference between the places that were projected to have longer recovery times and those that might have an easier time?

Cox: Yeah, perfect. So there were two main things, I would say. One was having multiple routes. So there are some communities that have multiple routes back to the valley, or they could go north or south. One of the other big, big issues were bridges. So there are some communities that relied on a bridge and those take much longer to recover so those are two of the things, multiple routes and bridges.

Miller: Are multiple routes, though, something that communities could add in right now or are they more or less stuck with what they have?

Cox: I think the second one, I think it’s hard to add multiple routes. There are ways to improve the bridges, retrofitting some of the bridges, and I think what our study was showing is having the resources to repair the roads closer to those communities would be a big factor in some of the cases.

Miller: Meaning for example what, like ODOT warehouses full of asphalt? I’m not, I’m not a civil engineer, but what would it mean for these communities to be able to, to say, fix a road or a bridge themselves?

Cox: Exactly. It would be locating some of the maintenance facilities out on our coast. So a lot of them are located along the I-5 corridor, for example, having some of them on the coast would definitely have, according to our study, would have a pretty big impact on the recovery times of some of these communities.

Miller: So then what happens next? I mean, because just to stick with this one, solution seems like too big a word, but, but at least, but way to approach recovery, that seems dependent on state resources and ODOT decisions. Where do you go from here in terms of talking to the people who need to get this information?

Cox: Great question. Next steps are actually to go back into the community. We have a state of the coast meeting every year. In the fall it’s going to be in Newport and the plan is to go back into the communities, talk to them, focus a little bit more on their, the assets, the things that they see are most important, that they most want to get connected to. It could be food or health, some of these other locations and then really just trying to work with them, almost on a community by community basis, that’s one of the next steps. Another big next step is to think of other aspects of the islanding. So it’s not just driving from A to B, but also having power and access to water. So those are some of the other things we’d like to add to our study.

Miller: How much do you think about this when you go to the coast?

Cox: That’s a great question. I love going to the coast. My family and we go there all the time, but I do think about what, what are the best ways to manage our risks on the coast? I mean we, it’s a beautiful place to go, great resource and we just have to manage those risks carefully. But I think it’s doable.

Miller: Dan Cox, thanks for your time today.

Cox: Thank you.

Miller: Dan Cox is a professor of Civil and Construction Engineering at Oregon State University.

Contact “Think Out Loud®”

If you’d like to comment on any of the topics in this show, or suggest a topic of your own, please get in touch with us on Facebook or Twitter, send an email to, or you can leave a voicemail for us at 503-293-1983. The call-in phone number during the noon hour is 888-665-5865.