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Gearing up for the big one

The state is working to fortify several highway bridges in Southern Oregon considered at risk from a Cascadia Subduction Zone earthquake
ODOT photo The Oregon Department of Transportation has begun “seismic triage” of 13 bridges in Southern Oregon that could fail in the event of a large earthquake.

When a massive earthquake isolates the Rogue Valley, a shortage of toilet paper will be the least of our problems.

With that in mind, the Oregon Department of Transportation, armed with money from the Legislature, has begun “seismic triage” of 13 bridges to ensure we have a lifeline to the outside world.

“We’re talking about life being much different than it is today,” said Gary Leaming, ODOT spokesman.

Because of the possibility that stores will be shuttered or emptied within days, and roads will be destroyed, the Oregon Office of Emergency Management recommends stocking enough essential supplies for every member of the household for at least two weeks.

Based on historical data, a Cascadia Subduction Zone earthquake is already overdue.

ODOT’s upgrades to bridges and slopes should allow for a quicker reopening of roads, though Interstate 5 into California is expected be closed for a longer period of time.

The idea is to provide some means of getting trucks into the valley from the east, which is likely to be less affected by an earthquake, forecast to be 8 or 9 on the Richter scale. The viaduct, which is the elevated structure on Interstate 5 through Medford, is expected to fail from an earthquake of that size.

In Josephine and Douglas counties, bridges along Interstate 5 are already being fortified.

In the Grants Pass area, ODOT is reinforcing footings and armoring columns at Exit 80 in Glendale, Exit 58 at North Grants Pass and another over Hillcrest Drive in Grants Pass.

In 2023, four bridges east of White City on Highway 140 will be upgraded to help ensure the reopening of this important east-west route.

In addition, ODOT will work on stabilizing slopes that have had slides in the past.

The slopes on Highway 140 are at Milepost 22.1. Three slopes on Interstate 5 south of Ashland will be stabilized at mileposts 2.5, 5.2 and 10.3.

Also in late 2023, three bridges on Highway 99 between Rogue River and Valley of the Rogue State Park will be replaced. The bridges cross Miller’s Gulch, Foots Creek and Birdseye Creek.

Bridge upgrades have been completed along Leland Road at I-5 in Sunny Valley.

The work on the bridges is made possible by $30 million from the Legislature and another $15 million derived from other sources.

Even after strengthening 13 bridges and stabilizing slopes on Highway 140, it could be days or weeks before trucks are able to make it back into the valley. That will affect everything from supplies of toilet paper to food to building materials.

But the seismic upgrades should mean major roads get reopened faster, though they might be reduced to a single lane in some areas.

The roads will provide an important lifeline that will bring in supplies and materials needed for the rebuilding effort.

As more money becomes available, ODOT hopes to strengthen more bridges in Southern Oregon and throughout the state.

State Rep. Pam Marsh said it has been difficult for public agencies to budget for this kind of emergency preparation, noting that California, which has had more earthquakes in recent memory than Oregon, has invested a lot into infrastructure upgrades.

She thought the ODOT projects would prove invaluable for the Southern Oregon.

“This region really made a point of gearing up around seismic safety,” she said. “We need to make sure we get in and out of the valley.”

Reach freelance writer Damian Mann at dmannnews@gmail.com.