COOS BAY — According to the Oregon Department of Transportation’s 2017 annual report, many of the bridges throughout Coos County are vulnerable to a seismic event.
“Our bridges are old, and most of them were built prior to the 1980s, when we stared thinking about seismic vulnerability and building for that,” ODOT’s bridge maintenance manager for South Western Oregon Bryan Mast said.
In the event of the Cascadia earthquake, most of the bridges in the county are likely to fail, leaving the populations in Coos County a mess of small disjointed islands.
“Based on the information we have, we’re looking at nearly 100 percent failure rate on the bridges ... if all those bridges were to fail, the county would look like chives on a baked potato. We’d all be cut off. A group of little islands,” Murphy said.
ODOT simply can’t afford to fix all the bridges in Coos County, at least not in any sort of immediate fashion. So, Mast is training ODOT crews in post-earthquake bridge inspection, as well as working to outfit all the ODOT offices in the area with satellite phones.
“We’re making sure we have sat phones at the different ODOT yards so that we have a communication link to our Emergency Operations Center in Roseburg ... we’re working on our conduit of information. That’s the best thing we can do right now is make sure that we have a communication plan and putting those pieces into place,”
Currently the ODOT yard in Coos Bay is only 5 feet above sea level. The Cascadia subduction zone is between 3 to 12 feet above sea level.
“As we move forward ODOT is trying to build a new facility here in Coos County that will bring us up out of the flood zone. We’re trying right now to figure out how to fund it," Mast said.
Mast hopes to start a sort of stockpile of materials like culvert pipes and piles of gravel at the new facility. The hope being that those supplies can be used to perform basic repairs to local bridges so that people can get to hospitals and other emergency services.
Coos County bridges are considered to be in the third tier of importance for ODOT.
“Most of Coos County is at ODOT’s lowest level of importance ... we’re kind of last on the list,” Murphy said.
ODOT’s plan is to make sure there is a path of bridges from Interstate 5 that are reinforced so that in an emergency situation supplies can be brought to the South Coast to aid afflicted areas.
State Highway 38 is the ODOT priority route into Coos Bay from I-5. Along Highway 38 there has been a lot of recent construction. Several bad culverts have been replaced along the road.
“We’re making sure that we have a chance to at least get supplies from I-5 down 38,” Mast said.
Highway 38 was chosen as the priority route because it follows the Umpqua River so closely that if there are landslides as the result of an earthquake the roads can be cleared by pushing the dirt over toward the river.
“Currently we’re doing everything we can ... I believe within the next 10 years we’ll see something going on around here,” Mast said.
According to ODOT, the Scottsburg Bridge along Highway 38 is in poor structural condition. It’s reported as having a low service life, and it’s listed as a scour critical bridge. Bridge scour is bridge material that has been eroded by abrasive, fast moving water.
“We’re in the design phase now to replace the Scottsburg Bridge,” Mast said.
Of the bridges on ODOT’s list of deficient bridges, the McCullough Bridge is the largest in our area. The McCullough Bridge is in good standing structurally, but it’s marked as vulnerable to seismic activity.
“The McCullough Bridge is a very tall, narrow bridge without seismic retrofitting at all. Will it be there? I don’t know, parts of it maybe,” Mast said.
If Cascadia hits before the ODOT completes the upgrades to their priority route it could be a long time before Coos County gets supplies from the outside world.
“In most areas you’re looking at a few days, but we could be looking at a lot longer than that. Without any way to drive in here they’re going to have to build a road all the way in,” Murphy said.
ODOT’s current project in Coos County is on Highway 42 just after it splits off from U.S. Highway 101. They are replacing a failing culvert. According to Mast, replacing the culvert will improve fish passage and open up the wetland to more fish. After that, they will be raising the overpass where Highway 42 goes over U.S. Highway 101.