Two engineering firms presented the City of Seattle and WSDOT with retrofit proposals that would repair and upgrade the existing bridges to meet earthquake standards, one proposed plan would do it without shutting it down!! But viaducts are an "eyesore" (quote from Seattle's mayor) and Washington is all about pretty flowers and a tunnel must be built. They can spend a $100 billion and never get it done. I've read the GNRR construction reports for the area, it's a friggin swamp and very unstable---I'm willing to bet that the project is never completed. As far as east side taxes vs west side taxes, taxes per capita (i.e. per person) for transportation projects are higher for eastern Washington residents.