SEATTLE - OCTOBER 24:  Seattle, Washington mayor Greg Nickels, left, and Washington State Governor Chris Gregoire walk to a signing ceremony near the Alaskan Way Viaduct October 24, 2009 in downtown Seattle, Washington. The viaduct, which was constructed in the 1950s and carries 110,00 cars a day, is slated to be replaced by a deep bore tunnel, which has become a divisive issue in the city's mayoral race. Getty Images logo Getty Images 28 months ago

SEATTLE - OCTOBER 24: Seattle, Washington mayor Greg Nickels, left, and Washington State Governor Chris Gregoire walk to a signing ceremony near the Alaskan Way Viaduct October 24, 2009 in downtown Seattle, Washington. The viaduct, which was constructed in the 1950s and carries 110,00 cars a day, is slated to be replaced by a deep bore tunnel, which has become a divisive issue in the city's mayoral race.