The coming Seattle-area traffic disaster?

Is there something that the Washington State Department of Transportation isn’t telling us?

Simultaneously, there are several large-scale transportation projects in planning or preparation stages: replacement of the 99 viaduct with a tunnel, replacement of the 520 bridge, and construction of the East Link of the light rail project. These projects individually would have significant impacts on traffic during their construction, however there will be many years of overlap between them which will cause a serious traffic nightmare. If you read the WSDOT pages, you don’t see any mention of any of these projects in relation to each other.

The legislature just approved tolling for the 520 bridge, this is a necessary and correct step. It will have the effect of diverting some traffic to 522 and I-90. At some point in the near future, construction will begin on the new 520 bridge further diverting traffic to the alternate routes.

The east link of the new light rail will run in the express lanes of I-90 removing two lanes of traffic in the peak directions. Currently, on many days, I-90 is stop and go even with these extra lanes. Diverting the current express lane traffic into the existing lanes (even with the additional proposed HOV lane in each direction) will already significantly slow down traffic on this corridor. Add to this the extra traffic diverted from 520 and I-90 will be a parking lot for several hours a day for many years.

I-90 feeds a significant amount of traffic to 99. When the viaduct is being replaced over several years, some amount of its traffic will be diverted to I-5. I-5 will also be getting additional traffic from cars diverting around 520 on 522. I-5 is already pretty bad, this will definitely make it ridiculous.

There are no definitive dates yet for a lot of these projects, but we’ll start seeing some of the first effects in the next few months. There doesn’t seem to be any real coordination going on around these projects or any acknowledgment on their cumulative effects to traffic in the short term from the state. If the duration of these projects were months or even a year, this would be somewhat reasonable. However, WSDOT estimates are for these projects to happen over the next 5-10 years. That isn’t reasonable for this to proceed without serious mitigation plans (even if they were to add significantly to the cost or the time lines).

Right now, it just seems like everything is up in the air so WSDOT isn’t addressing the potential issue. That makes it seem more like they just hope that no one notices…

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