Alaskan Way Viaduct costs escalate in Washington State

| 9/21/2006

The Washington State Department of Transportation has revised its cost estimates for two major construction projects.

The latest cost estimates are not surprising – engineering and construction costs are going up on the proposed Alaskan Way Viaduct and seawall replacement project in Seattle and the State Route 520 Bridge replacement project over Washington Lake that includes high-occupancy-vehicle lanes.

In an announcement Wednesday, WSDOT estimated a re-evaluated cost of $4.63 billion on the Alaskan Way Viaduct tunnel and $2.82 billion on Viaduct elevated structures, up from $3.63 billion and $2.36 billion, respectively.

On the SR 520 Bridge and HOV lanes, the estimates rose from $2.02 billion to $2.79 billion on the four-lane alternative; $2.83 billion to $3.9 billion on the six-lane alternative to include the Montlake Interchange; and $3.1 billion to $4.38 billion on the six-lane alternative to include the Pacific Interchange.

Proofing for earthquakes adds to the cost estimates, WSDOT officials said.

Construction is slated to begin in 2010.

“These estimates introduce a new number, the ‘likely cost,’ as our best way of giving the public good project comparisons when tomorrow’s inflation rates are hard to guess and ‘worst case’ ranges are more pessimistic than the future we actually expect to encounter,” David L. Dye, Urban Corridors Office administrator with the Washington State Department of Transportation, stated in a press release.

“Our project design and construction efforts will, we hope, stay very close to the ‘likely range’ estimates.”