The same morning we wrote about the economics of highway removal and suggested we try closing the viaduct, Mayor McGinn was saying something similar on KUOW.

So is Michael van Baker at the SunBreak (which has a wonderful new site design, by the way).

So is Danny Westneat at Seattle Times.

In fact, as Westneat points out, a group of UW faculty suggested the same thing five years ago:

I called one of them, earth-sciences professor Dave Montgomery, to see if he thought anyone might listen now. What with quakes and the mayor so much in the news.

“We wrote that five years after the Nisqually quake,” he mused. “Now another five years have gone by. It’s really starting to get into geologic time.”

Westneat muses that the only reason the Viaduct is still open is because we are afraid of something we do not even know will happen: crippling traffic. There have been large transportation closures before and the city didn’t stop moving, so why are we so sure it will happen this time?

Gridlock is what they forecast when they shut most of I-5 a few years back. There could be 30-mile traffic jams, they said. It never happened.

Same thing when they shut the downtown bus tunnel for two years. Buses would jam the streets, they said, triggering big tie-ups. Also didn’t happen. In fact, Metro said buses moved through downtown more swiftly, on average, than before the closure.

These were not miracles. If you give drivers a heads-up before a road closure, and also make a series of adjustments to the system, the predicted crush of humanity often never materializes.

In the case of I-5, an astonishing 50,000 cars that normally use the freeway didn’t appear. And didn’t jam side routes either.

The Viaduct currently carries about 108,000 cars each day. So if tens of thousands of vehicles simply stop making the trip entirely, we’re already getting close to the estimated number of cars that would end up on city streets and I-5 even after completion of the proposed deep bore tunnel. Remember, 60 percent of vehicles on the viaduct are accessing downtown neighborhoods, anyway.

So, without an Alaskan Way boulevard (as is proposed in both the surface/transit and deep bore plans), would traffic downtown be worse than it is now if we closed the viaduct? Probably. Would it be anything close to catastrophic? I highly doubt it. Is it worth continuing to take the risk? No. But Councilmember Tom Rasmussen, chair of the Transportation Committee, certainly thinks so:

“It’s amazing to hear the mayor say that,” said Seattle City Councilmember Tom Rasmussen. “The viaduct carries 110,000 vehicles a day. To shut the viaduct down, it would be total gridlock.”

People have also accused the mayor of using the earthquake in Japan for his own political gain, but that is not fair. The state does not need the viaduct to stand until 2016 in order to build the tunnel. He is not saying, “Oh, an earthquake, let’s get out and sign those anti-tunnel initiative petitions!” Watching the horrendous disaster still unfolding across the sea from our city should be a humbling experience for a good leader, and shutting down and demolishing the viaduct as soon as possible is the only responsible course of action our city can take.

In case you haven’t yet seen it (or have chosen to ignore it), here’s a video by WSDOT (not the mayor) showing what could happen in an event fairly similar to the 2001 Nisqually quake:

UPDATE: WSDOT’s Paula Hammond will be on KUOW’s Conversation at noon today.