EDITOR'S NOTE: Typically, we ask that our letter writers stick to the 250 word limit, and when they don't we usually chop them down to size, literally if not metaphorically. In this instance, however, we thought we'd make an exception, this being such a timely and controversial issue.
Thanks.
Earl Reilly's guest column Bono stops the traffic-and the Seattle viaduct in the March 14 issue of the Magnolia News makes an argument for tearing down the viaduct, based on the assertion that the Cypress Expressway that collapsed in the Loma Prieta earthquake of 1989 in California and the Seattle viaduct are similar and vulnerable to the same type of failure.
In fact, the Seattle viaduct's visual appearance (it looks almost identical to the Cypress from a distance) is as far as the similarities go. Our viaduct is a very different structural design and safer than either of the Bay Area structures that failed during their earthquake.
Mr. Reilly is, unfortunately, one more victim of misinformation spread during the viaduct debate. The question of the similarities and risks of the Cypress vs. the Seattle viaduct was addressed directly by one of the world's leading bridge design firms, TY Lin International in a 2001 report commissioned by the Washington State Department of Transportation (WSDOT).
For the record, WSDOT and many others recognize TY Lin as the true experts in bridge design and construction. The viaduct is, for engineering purposes, a bridge built over land.
The TY Lin report describes the significant structural differences between the Cypress Viaduct and the Seattle viaduct. Two critically important differences between these structures are that the Cypress Viaduct was built using sliding joints and hinges in order to ease the construction process for expansion, whereas the Seattle viaduct was built without sliding joints and hinges.
The Cypress design was a problem because once the joints moved off of their seat the structure holding up the roadway was no longer supported, and it simply failed-causing the roadways to collapse.
The Seattle viaduct roadway design by comparison is not subject to such a failure because its design holds the roadway surface in place.
The major problem facing the Seattle viaduct is not the actual structure but rather the fact that the soil was not properly prepared when the structure was built. It is this soil, under one small area, that needs to be repaired.
Contrary to predictions by WSDOT and others that the viaduct would fail under forces much less than the last Seattle earthquake, the only movement was in the area of the defective soil. So far, WSDOT and SDOT are not making any moves to repair the defective soil area but instead concentrate on measuring the motion at those points.
To put this in context, if the soil repair alone were done, the Seattle viaduct would ostensibly remain standing after numerous Seattle structures with less earthquake resistance had fallen to the ground.
Notwithstanding WSDOT's controversial estimate of more than $2 billion for a retrofit, TY Lin priced the project at $948 million in 2001, giving the structure a life of 50 more years without the massive disruption of a new structure.
So, if we replace the viaduct, it is because we want to, not because we must. When all of the arm waving is done, the technical facts are clear.
Every dilemma is an opportunity to rise above the rhetoric and the spin. There is nothing I would appreciate more than seeing a solution that serves all of our citizens, including those that commute or move commerce to and through Seattle, those of us that pay (already burdensome) taxes and the families who could enjoy a new park.
In the final analysis, whatever the decision, I hope it is made based on a true and accurate representation of the facts and not supposition or statements biased toward a particular position or interest.
Dan Labriola, a Magnolia resident, is an engineer and a naturopathic physician.
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