Shut the Alaskan Way Viaduct down

In yesterday's Seattle Times, columnist Danny Westneat muses over the city's painless adjustment to the closure of the downtown bus tunnel for light rail construction, and he proposes an experiment:

So here's my modest proposal: Let's just try it. Close the viaduct. It's unsafe anyway, remember? Let's come up with a thousand-point plan like they did for the bus tunnel and shut down the viaduct for a month or two. Then see what happens.

We agree with Danny. In fact, back in October of 2005 we penned a letter to Governor Christine Gregoire urging her to shut down the viaduct and post warning signs around it about the dangers of an earthquake.

WSDOT will, of course, tell you the viaduct is safe to drive on - and there will be others who will insist a comparison to the bus tunnel closure doesn't make sense. And Highway 99 is one of only two free flowing routes through Seattle. But it's worth recognizing several things:

• Whether we rebuild the viaduct (a bad idea), build a tunnel (a good idea, if we can get over the cost hurdle) or simply tear it down (an option that shouldn't be off the table) the viaduct will still have to be closed at some point. And mitigation (doing a "thousand little things") will then be necessary.


• We need a contingency plan in place in case the viaduct gets put of commission by a disaster or the discovery of a weakness during a maintenance inspection, or some other problem. And no plan is a known good one unless it's tried out. Call it an emergency readiness test.


• If an earthquake does happen (whether a minor or major trembler) and the viaduct sustains damage, it's likely that the structure will have met its end. Repairs may not be possible at that point, and even if they happen to be, they probably wouldn't be worth it. The viaduct would have to come down - or the rubble of it would have to come out and the waterfront cleared. Earthquakes are unpredictable. An earthquake could happen tomorrow. Experts say there's 1-in-20 chance that the viaduct could be shut down by an earthquake within the next decade.

In the Loma Prieta earthquake of 1989, the Cypress Street Viaduct in San Francisco unexpectedly collapsed, causing 42 fatalities. The structure was built on filled land, which is highly susceptible to soil liquefaction during an earthquake (and exhibits larger ground motion). The similarities to the Alaskan Way Viaduct are unnerving.

I make a habit of staying away from the Alaskan Way Viaduct. I try not to drive on it, park under it, or walk under it. I see something ominous in that hulking concrete structure and I personally can't wait until it no longer exists.

On its website, WSDOT says:

As the Governor stated in her findings, "no action" is not an option. The longer we wait, the more we risk. The viaduct and the seawall are at risk of failure from earthquakes (with unacceptable risk to lives as well as property) or irreversible loss of use from age and deterioration.

Since no action is not an option, since safety is a paramount concern, and since the viaduct will have to be torn down under any replacement scenario, it would seem we haven't got much to lose by shutting the structure down now.

Critics can whine about "economic losses" resulting from a viaduct shutdown all they want. That won't change the fact that a planned shutdown and mitigation will be far less expensive and disruptive then a shutdown caused by a disaster. A planned closure has to happen sooner or later or the structure will never be replaced. We may as well get started.