Adele Ferguson

I WORRY more about earthquakes taking out bridges than I do about what happened with the Skagit River bridge, where a trucker with a too high load bumped the infrastructure and knocked a section out as if it were made of Legos.

Actually, I’m paranoid about bridges. It’s been many years since I last walked across one, clinging to the guard rail, and every time I drive over one, I say a little prayer that I get to the other side before an earthquake hits.

THE LAST TIME I wrote about bridges, I talked to Al Walley, the then bridge expert for the Department of Transportation, who found it amusing I worried more about being on a bridge during an earthquake than in a building. But you have to admit we are often warned we sit in the middle of a series of faults, particularly in Puget Sound, and are way, way overdue for The Big One.

There were at that time, 1990, about 3,150 bridges of all kinds compared to today’s 7,700, a figure I read in the Seattle Times the other day. That included highway overpasses, pedestrian and railroad crossings. Even the Seattle Convention Center was considered a bridge since it crossed a freeway. There were 20 crossings of the Columbia River.

MOST OF THE BRIDGES were designed to consider the seismic load, that is how to accommodate the stresses generated by an earthquake.

“We’ve been factoring in seismic load since 1950,” he said.

What that means is the structure is designed to resist the force generated by the motion of a quake, or be flexible enough to give a little. The Tacoma Narrows suspension bridge, a loner the last time I wrote, would be a good place to be in a quake, Walley said.

“You might not like the ride, but it would be pretty safe. The same goes for the four floating bridges, the one over Hood Canal and three on Lake Washington.”

Half of Hood Canal and one of the Lake Washington bridges sank but in storms, not quakes, and were rebuilt.

I guess then, I said, the worst place to be in an earthquake would be on or under a highway overpass. At least that’s what it looked like in pictures of recent quakes in California.

“We’ve had two severe quakes, and I never remember an overpass crumpled on the highway,” said Walley.”

AT THAT TIME the state had recorded history at least 60 years back and in it 48 bridges “failed” which is what they call it when a bridge is wiped out one way or another. Farthest back on the list was one in 1931, lost in a fire when its wooden deck burned up. Actually, 24 of the 48 failed bridges were lost to floods. Two fell March 27, 1964, on the Copalis River, as a result of the tsunami from the Alaska earthquake.

So, where was the oldest bridge in the state? “In Spokane,” Walley said, “The concrete arch bridge over the Spokane River at East Trent was built in 1910.” So was it being replaced? “Nope,” he said. “It’s satisfactory for traffic. These are tough old bridges.”

That one is tough all right because I checked the other day with DOT and was informed by Barbara Pacifico that while Al Walley is long gone from DOT, the Spokane River bridge at East Trent is still standing and in use at age 103. It is on the list for replacement in 2018 or 2019, she said.

I wish it well. I suspect with its history that it will outlast me. They knew how to build bridges back in 1910.

(Adele Ferguson can be reached at P.O. Box 69, Hansville, Wa., 98340.)