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Friday, May 19, 2006

Study the Retrofit? We Already Have

Posted by on May 19 at 11:23 AM

Nick Licata, David Sucher, and others have argued that the Washington Department of Transportation (WSDOT) should consider retrofitting the existing Alaskan Way Viaduct to withstand a major earthquake, rather than digging a tunnel, building a new viaduct, or simply tearing it down. Their complaints have prompted the DOT to agree to spend eight weeks studying a proposal by two retired engineers, Neil Twelker and Victor Gray, to brace the viaduct with a system of steel beams, shock dampers, and angular supports.

This sort of thing is exactly why we’ve been talking about the viaduct for five years instead of doing anything about it. WSDOT, after all, has already been down this path once before, in 2001, when its consultants concluded that the retrofit proposed by Gray and Twelker would not protect the viaduct in an earthquake. Nor would it address the eroding seawall, which also needs to be replaced. A retrofit, the study concluded, “may be effective in keeping certain sections of the viaduct intact [in an earthquake] but it will not serve the purpose of making the structure safe overall.”

In addition, the report continued, the retired engineers’ cost estimates - they now claim a retrofit could be done for $800 million, compared with $2 billion for the cheapest rebuild alternative - were “oversimplified” and “too low.” For example, the engineers estimated that jet grouting in the soil underneath the viaduct (basically turning the soft, liquifiable soil into concrete) would cost just $700,000, a figure WSDOT said ignored “the extra costs of working in difficult conditions, around and over traffic, challenging construction techniques and other peculiarities of the project.”

Then, in 2003, another study concluded that retrofitting the viaduct would be both less safe and only slightly less expensive than rebuilding it. Meanwhile, “after” renderings of the viaduct provided by Licata’s office showed a nearly solid box of concrete, with pillars twice as large as the current structure’s.


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Hi Erica,
Perhaps you could give readers the key link:
'You can't get there from here.'.

It's not so much that I think that the Retrofit is the cat's meow or that I believe that the Viaduct is ideal. (My own opinion is actually fairly irrelevant.)

What I am trying to get across is that the Retrofit is politically inevitable and we might as well all get real about it. I do not believe that there is a great deal of choice once you start thinking through the money avaiulable and the real world scenarios. Please go back and read my link. I may very well be wrong but no one so far has explained the errors of my logic. Have at it.

•••

As to WSDOT's conclusions, why is such a usually skeptical journalist i.e. you, now such an advocate for them? So fervently supporting WSDOT? You accept its views that a Retrofit wouldn't work. Yet you don't accept the Gray/Twelker claim that a Retrofit will work. Do you have the technical background to be able to judge the competing claims & assertions?

I know I don't have that ability.

But I do know that Gray and Twelker and others are very well-respected engineeers. So why not listen to them carefully?


People who want to replace the viaduct do not care now big, noisy, or unattractive the structure is or what it does to downtown. The number of pillars could be doubled and tripled in size and they would not care. The viaduct isn't in their neighborhood. They haven't been to the waterfront in years and don't care to visit or to know why anyone would want to visit. And since they don't care about the waterfront, they also don't care about the water or how clean it could be or how the viaduct affects it.

David:

No, I don't have the technical background. If that's the requirement for having an opinion, only engineers should be allowed to comment on the viaduct. However, as a longtime transportation reporter, I do question any estimates (e.g., $700,000 for jet-grouting the soil under the entire viaduct) that seem too low/good to be true. And I think the renderings I've seen of a retrofitted viaduct - twice as bulky as the current structure - speak volumes. I'm no fan of the current viaduct, aesthetically speaking, either, but I do think a retrofit would be worse.

As for the default, I actually think it's the surface/transit option (as I believe you've mentioned on your blog). If the viaduct is torn down, and if we don't secure the billions needed to replace it, the surface/transit alternative will be the path of least resistance.

And finally, I linked the whole blog because you've been writing a lot about the viaduct, not just that one post.

The viaduct has been where it is for fifty years. Too bad for people who moved there long after its construction and now self-righteously whine about how it dares to trespass on "their" neighborhood.

I'm a civil engineer; I'm an earthquake hazard expert. David Sucher is neither, but seems to be rather impressed with Gray and Twelker to the point where he's willing to ignore the analysis and opinions of the many engineers (of equal or greater merit from WSDOT, private industry, and UW) who have studied the structural integrity and retrofit options of the viaduct dating back to 1996. I'm also generally skeptical of WSDOT (because they are a road building outfit not a transportation agency; probably similar reasons as to ECB's skepticism).


Gray and Twelker's retrofit idea is irresponsible. (Granted, disaster reduction is what I focus on.) The question is not whether it will *work*. No doubt it will stand after retrofits are complete; but will it stand when an actual earthquake hits? The question is whether you want to take the *risk*. Let's be clear on the biggest cost savings of the G&T plan: reducing the size of the earthquake to design for--from a 2500 year event (what the tunnel & rebuild would be designed for) down to a 500 year event. Either one of these earthquakes could happen tomorrow (it's not a "once in 2500 years" thing...it's stats); though, yes, one is more likely than the other.


WSDOT's retrofit plan also was more expensive (and bulkier) because they felt it was responsible to retrofit the entire structure and not try to guess at a) what elements require retrofit and b) what shoring up some elements will do to stresses in non-retrofitted elements. I think it is fully within WSDOT's jurisdiction to say that they will not take part in building something that does not meet their criteria for seismic safety--something the tunnel, rebuild, and transit+streets options all would meet. (The transit+streets option is arguably the most seismically safe because reduces dependance on complex engineered structures that have a finite possibility of failing under intended conditions.)

Some engineers sort of assune they can design a quake-proof replacement for the viaduct. Fine, but what's to prevent the long predicted BIG ONE from happening next week and collapsing all of the manmade downtown Seattle waterfront, or from happening in the midst of the tunnel project?

While some engineers may be convinced that they could have designed a structure to withstand the cataclysmic mudflows when Mount St. Helens erupted, they couldn't have.

For that matter, what about predictions that global warming could raise West Coast sea levels by 20 or 30 feet a few decades from now? What good will the proposed waterfront tunnel or surface boulevard do then? I'd rather take my chances on a raised viaduct retrofit.

Some engineers sort of assune they can design a quake-proof replacement for the viaduct. Fine, but what's to prevent the long predicted BIG ONE from happening next week and collapsing all of the manmade downtown Seattle waterfront, or from happening in the midst of the tunnel project?

While some engineers may be convinced that they could have designed a structure to withstand the cataclysmic mudflows when Mount St. Helens erupted, they couldn't have.

For that matter, what about predictions that global warming could raise West Coast sea levels by 20 or 30 feet a few decades from now? What good will the proposed waterfront tunnel or surface boulevard do then? I'd rather take my chances on a raised viaduct retrofit.

Erica,

Well of course you have the right to an opinion. We all do. Maybe we even have a duty as citizens to opine and I had no intention of suggesting otherwise.

But if a public policy opinion is based on judging competing technical arguments — which is what I think you have done — and then making conclusions about what is feasible and what is not, and yet one doesn't have the technical background, well I hope you see that the opinion is diminshed in value as to the extent it relies on technical judgments. (I hope that is not too convoluted.)

There is a natural tendency to respect authority simply because it is "authority." We pretty-much all do so. I am merely surprised that of all local media, The Stranger's urban planning reporter would seem to enthusiastically accept WSDOT's side of the story without (I gather) interviewing Vic Gray et al and asking for their story. I am pretty sure you have talked with the PWC folks. Why not give the Retrofit some ink?

I don't believe that I have anywhere vouched for the Gray/Twelker plan except to state the obvious -- these guys are well-repected professionals with many years of experience and that we should listen to them.

My other arguments are based on my perception of local politics etc -- they are NOT technically based except as to take Gray/Twelker as credible voices.

•••

However, I agree with you entirely that there is something troubling and odd that five years after the quake we are still dithering over what course to take. But it is NOT because people have been urging a Retrofit. The simple fact is that there is not enough money for the alternative (the Tunnel) chosen by the Mayor and the Council and no one seems to know how to cover the gap. If the money was there we'd be under construction. No?

Check your facts ECB - Councilmember Nick Licata has NOT, since 2003, "argued that the Washington Department of Transportation (WSDOT) should consider retrofitting."

He DID attend an event hosted by the team proposing that this be reviewed again and he accepted a request from that team asking that the Council consider placing this option on the ballot with the tunnel and rebuild option.

After that event, Councilmember Licata asked me to send a memo to Councilmembers that said nothing more than this:

Councilmember Licata has asked me to distribute the attached proposal from the Viaduct Preservation Group (VPG). He has asked that you review this proposal and respond to him in regards to the VPG request to include the choice of retrofit on the November ballot.

If next time you want to check what Nick's position is before SLOGGING, you know how to find me!

And for the record, the idea that WSDOT is studying the Retrofit even remotely because of anything I have written is flattering but absurd.

I think that WSDOT is realizing some of the financial/political and subtle logistical difficulties involved with both the Tunnel and the Rebuild.

The Retrofit is simply a logical alternative which it must examine.

Erica, again, knowing that you support the surface option, it's probably in your best interests to stay mum and let the city pick whichever option they want, because once the viaduct is torn down and citizens have to live without the viaduct, assuming the city doesn't economically implode, the circumstances themselves will make a strong case for not wasting the money on a rebuild or tunnel and just doing without the viaduct.

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