A Washington State Department of Transportation official affirms that the cost will be at least $6.14 billion---and probably far more than that---to build a deep-bore tunnel to replace the Alaskan Way Viaduct.

The previous estimate of $4.24 billion was only for construction costs and did not include financing costs. Amy Arnis, the Chief Financial Officer of WSDOT, told the Seattle Weekly earlier this week that it would cost $1.9 billion to pay off the interest on the construction bonds---and that was only for the $2.4 billion portion of the state’s pledge, not for the bonds financed with tolls or by the city, county, or the Port of Seattle. So the total financing package is likely to be far more than $6.14 billion, and that’s before cost overruns.

The majority of that $6.14 billion is still a hope and a dream. Only $2.4 billion in firm funding has been identified. The Legislature’s tunnel bill said the state would contribute another $400 million to the project costs from tolls, but a 2002 WSDOT study (.pdf file) has already concluded tolls could finance no more than $95 million of a Viaduct replacement.

The rest will materialize only if several conditions are met: the Port of Seattle Commission votes to contribute $300 million, the Seattle City Council votes to raise taxes and fees by nearly $1 billion, and the Legislature grants---and the King County Council uses---the authority to impose a motor vehicle excise tax on automobiles in the county.

Against this background, here are some questions about the tunnel’s financing that state and local leaders still have not answered:

• How much will the interest be on the bonds financed by the city, county, and Port of Seattle, and what taxes will be used to pay that interest?
• How realistic is it for tolls to finance $400 million in construction costs when the State’s own 2002 study found that tolls could finance only $35-$95 million of a Viaduct replacement?
• Will the Port of Seattle’s $300 million contribution require the Port to levy a property tax on King County property owners?
• Which taxes and fees does the City of Seattle intend to raise for its share?
• A Seattle ordinance prohibits a “local improvement district” from being formed without the consent of affected property owners, so what will the city do if downtown property owners refuse to pay a share of the costs?