Earthquake simulation highlights the vulnerabilities of the Alaskan Way Viaduct

Sunday, October 25, 2009

By guest blogger Ron Paananen

The double-deck Alaskan Way Viaduct, a fixture on Seattle’s downtown waterfront for more than five decades, was already showing signs of wear and tear when the last major earthquake struck in 2001. That 6.8 magnitude seismic event further weakened the structure by damaging its joints and columns and causing sections to settle into the loose fill soil in which it was built.

In the years since, crews have kept a close eye on the viaduct through quarterly inspections and have strengthened several columns to prevent further damage to the structure, but the threat of another earthquake was always present. During this time new soil data and a better understanding of local and regional seismic behavior clarified exactly how vulnerable the viaduct is to another earthquake. In 2007 we released a report that concluded there is a higher chance – specifically, a one in 10 chance in the next 10 years – of an earthquake occurring that could cause portions of the viaduct and adjacent seawall to collapse. The vulnerability analysis is available on our Web site.




A simulation based on the 2007 report demonstrates how disastrous a strong earthquake could be for the Alaskan Way Viaduct. It shows what could happen if a seismic event more intense than the 2001 earthquake were to shake the Puget Sound region again. To say that the damage to the viaduct and the seawall would be severe would be an understatement.

We understand the risk, and we are making progress to replace this vulnerable structure. Early next year we will begin major construction to replace the southern mile of the viaduct, and the state, King County and the City of Seattle have agreed to a plan to replace the section along the waterfront (The plan, calling for a bored tunnel beneath downtown, is currently under environmental review.) State and city crews also continue to monitor the structure and ensure it remains safe for drivers.

We are also installing an automated closure system next year that will keep drivers from using the viaduct after an earthquake, fire, or other event compromises the structure. The new system will use the latest in monitoring technology, including GPS antennas and wireless equipment, to detect structure and ground movement. New signs and gates at the viaduct’s ramps and entrances will detour traffic away from the structure during an emergency, and advance warning signs will notify drivers in SODO, West Seattle, downtown and north of Seattle about any closures.

The specter of another major earthquake, however, is always present. That is why we are determined to replace the Alaskan Way Viaduct before Mother Nature makes the decision for us.




You can watch the video on our streaming server if you can't access it on YouTube.

27 comments:

Anonymous said...

So, this was withheld from the advisory committee because it could affect the outcome of the stakeholder process. Then you wait until a week before a pivotal local election to release it? How can you honestly say the timing isn’t political?

The video was made by Parson Brinckerhoff, a construction company that will make millions on the tunnel. This is the same company that has placed, Jared Smith, one of their top executives on Mallahan’s “kitchen cabinet” and given him campaign contributions.

Timothy said...

WSDOT...please tell us why you chose to release this video today? The timing of it looks very suspect.

Further, what possible reason do you have to NOT shut this down today? Instead, you're working on the longest possible delay for the closure of the Viaduct.

So, while the video is intended to scare people into moving forward on the tunnel project, the reality is the tunnel project keeps the Viaduct in use much longer than other, lest costly alternatives.

Anonymous said...

Interesting comment Anon... but in the opening paragraph of the note in e-mail it was said this was released due to a Freedom of Information Act filing. That could have come from a newspaper, blog, or whatever. It appears that the nature of this video is why the State DOT attempted to embargo it until AFTER the election. Looking for consperacy, you maybe should see who filed for FOI release. It may not be what you seek to think it is. Just sayin...

Quinn said...

Now show us an earthquake simulation of the millions of tons of seismically liquefied mud that would flow inside the deep bore tunnel, if it were built --as is now planned despite voters' opposition. GO SURFACE - VOTE McGINN.

Anonymous said...

I second what Quinn said - show us how this same earthquake / fill liquefaction would impact the deep bore tunnel.
Frankly, I think I would prefer being above ground and take my chances to being buried alive.

Anonymous said...

Gawd I love a good disaster movie...I'm going to go microwave some popcorn and watch this BS video again....just can't get enough pulp fiction!

Anonymous said...

Having lived through the Kobe Earthquake (Richter Scale 7.6) in 1995, and seeing something similar to this simulation for myself, I can assure you that this is neither a joke or a laughing matter. Politics aside, the sim is fairly accurate, and depicts what would happen. I saw the collapsed Hanshin-JR Train line viaduct for myself. I walked over a bridge from Kobe Port Island to downtown Sannomiya that on both ends, had collapsed ramps. I saw tilted buildings which later fell over. The collapsed City Hall building where upper floors pancaked onto lower floors. Failure to seawalls allowed liquefied soil to spill into Kobe Harbor on Kobe Port Island. Most of the deaths occurred from the fires that sprang up within minutes. It was seven years before commerce came back into post-earthquake form in Kobe. Aside from the disaster, Seattle would face untold damage to commerce. Probably this would have a ripple effect on local and maybe even national economy for years to come. So to you naysayers, study your geology. We are simply too complacent. As we're afraid to pay higher taxes now to fix the problem, we sure will kick ourselves later.

Anonymous said...

Whatever the political reasons are or not, facts indicate that we got lucky that this didn't happen in 2001. We were warned in Dr. Kramer's 1995 report and we're still years from closing down this road...unbelievable. So much for putting safety first.

Andrew McCullough said...

It was an interesting video... no sound, though? I'd like to watch it without the interruptions of text - give it a full playback option.

I wouldn't be surprised if actual damage were much, much worse, especially considering the decomposed state of the sea wall.

Anonymous said...

OK so how much did this one cost the tax payers. The person authorizing this expense should be fired Period! We know what a multilevel freeway collapsing looks like from the video and images of the Cypress Freeway collapse in CA. This is purely a political move on the part of the DOT in order to scare people into supporting the replacement of the viaduct. I call for tearing down the Convention Center and widening I-5. If you really want to improve traffic in the downtown corridor that is what has to happen because traffic problems come from the narrowing of I-5 down to two lanes under the Convention Center. The Convention Center is the only reason we can't widen I-5. With I-5 wider we wouldn't even need a replacement option for the Viaduct.

Anonymous said...

Typical responses from people that don't understand seismic events. Quinn mentioned showing a "earthquake simulation of the millions of tons of seismically liquefied mud that would flow inside the deep bore tunnel", obviously you design the tunnel so it doesn't collapse under liquefied conditions, besides in any design you "treat" the surrounding soils so it doesn't liquify during a seismic event.

jniles said...

For some real life photos of what will happen in a Big One, Google for images of [Loma Prieta Cypress Viaduct] an earthquake caused viaduct collapse in Oakland, California 20 years ago.

One example photo is http://www.nasa.gov/centers/goddard/images/content/65678main_freeway_m.jpg

Quinn said...

The liquefied soil would still flow in through the openings at the tunnel's ends, wouldn't it, "Anonymous"? Mother Nature doesn't normally pay heed to the hopeful ministrations found in tiny Man's "treating" a patch of soil.

Anonymous said...

A low point for WSDOT -- a shameful episode in releasing this video with such fanfare. WSDOT's explanation for the release also strains credulity.

There's apparently nothing too low for this governor and WSDOT to stoop to in order to make sure special interests -- who stand to make millions off a bored tunnel -- are happy.

Does this count as an in-kind contribution from a public entity to the Mallahan campaign? Something stinks to high heaven in Washington.

Anonymous said...

Apart from this being overtly political (I didn't realize that WSDOT or Gregoire would stoop to this place), WSDOT's revised stance on taking the Viaduct down doesn't make sense.

Originally, Gov. Gregoire promised she'd have the Viaduct removed by 2012. Now, with the tunnel option on the table, WSDOT (and Gregoire, I presume) are looking to delay the Viaduct's removal for another few years.

Why?

WSDOT's posting of this video is certainly not based on safety concerns (or a fallacious claim that its hand was forced by a public disclosure request; if so, why not post the rest of the documents requested?). If so, WSDOT would fulfill the Governor's original promise to take the Viaduct down by 2012. Instead, WSDOT plans to keep it up as a measure of convenience - irregardless of the "safety concerns" that this blog so cynically espouses.

Anonymous said...

There is absolutely no way I'm ever going through the viaduct or a new tunnel! Thanks for the reminder.

EL said...

Thanks for the video. We need to shut down such unsafe structures - our infrastructure is too outdated and dangerous.

Anonymous said...

I like how nobody bothered to actually look at where the tunnel is going to go.

It is not going under the location of the viaduct, it's set much further from the shore:

http://www.wsdot.wa.gov/biz/contaa/DESIGNBUILDCONTRACTS/SR99AWVBoredtunnel/AWV%20RFQ%20Figure%201.pdf

The surface project is built on said liquifiable fill. So, in the event of a quake, we would see similar results to what's seen in the video. So basically, we'd have spent all that money on the surface project and then turn around have to dig the tunnel anyway. What a savings.

Anonymous said...

El's right. This would have been the result in 2001 had the epicenter been closer or the magnitude a fraction higher. All structures have a life span and the viaduct is way past due, especially given the previous damage. Replacement measures should have begun a decade ago, and the tunnel option which is farther inland, would not be affected by Elliott Bay influences.

Anonymous said...

The information was released because there was a request for public disclosure and WSDOT was forced by law to release it. Secondly Quinn if you remember the tunnel and above ground options were all voted down buy the voters more than once. So in that case should we just do nothing and wait until the viaduct collapses before we do anything?

Anonymous said...

Everyone must remember that this video is a representation of what would happen if nothing were done. Whether or not it's politically motivated is not the point here. What is, is that if nothing is done, damage could be catastrophic, and the viaduct needs to be removed.

Liquefaction would occur regardless of the waterfront alternative chosen. Just because less expensive alternative is built does not mean the ground would not liquefy, and fall into the Bay.

I would hope, however, that with any new alternative (whether a surface, bored tunnel, etc) that measures are taken to strengthen the structures in the area and to protect against liquefaction. There is no perfect solution, but steps need to be taken to prevent a catastrophic collapse of infrastructure.

And, what’s to say that other structures in the area wouldn’t also experience collapses. Yes, this is specifically looking at the Viaduct, but what about I-5 and other bridges in the area.

Anonymous said...

All they had to do was google images of the 89 loma prieta quake, to see the damage to the cypress and embarcadero freeways. Or any of the other damage in SF, this was just another waste of tax dollars that could have been used elsewhere.

Anonymous said...

This obvious attempt at manipulation of voters' thought just before an election is abominable and unfit for a democracy. The DOT administrator who authorized the spending of an outrageous amount of money on this piece of junk should be fired. Gregoire and her DOT buddies are sinking lower in my estimation all the time.

Sean said...

Typical gloom and doom. I like how they mention "no tsunami expected at the end." I guess they don't think we're dumb enough to think they can fix that problem.

Anonymous said...

As a survivor of the Loma Prieta earthquake and seeing the Cypress structure first hand the very next day, two words come to mind: horrific and heartbreaking. Not only did the Cypress structure collapse, but the Embarcadero on the S.F. water front, which was also a double decker, was badly damaged too. Both structures have the same design as the Alaskan Way viaduct. The Alaskan Way viaduct WILL come down.

The question is, "Which way do we want it to come down?". I sincerely hope that it isn't because of an earth quake. Indecently, the Embarcadero was replaced by a surface street. Gone now is the Berlin Wall feel of the S.F. waterfront.

Mathew said...

It would be great to see WSDOT reach out to the Citizens most impacted by it's actions. Tolling on Hwy 520 is going to kill children on the streets of Kenmore, Juanita and Lake Forest Park. Our voice will not be lost in the wilderness.

http://www.facebook.com/home.php?#!/pages/TollingImPAC/171458756212976

Vox clamantis in deserto!

Anonymous said...

wow, well now I know where to avoid when I visit Seattle. Just think if the Cascadia rips off a 9.0 with about 5 minutes of shaking. My Niece just moved out there from MN, I'll be she to let her know too, although she's probably already heard about this. I can't believe people are actually against rebuilding this archaic roadway.

 

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