Alaskan Way Viaduct replacement reaches final environmental review milestone

By guest blogger KaDeena Yerkan

This week a small group of WSDOT and Federal Highway Administration (FHWA) officials gathered in a conference room in downtown Seattle to watch something that will change the course of history in Seattle.

With little more fanfare than snapping a few photographs, FHWA’s Washington Division Administrator Dan Mathis, signed the SR 99 Alaskan Way Viaduct Replacement Project’s Record of Decision. While the document has a long and bureaucratic title, its intent is clear. It means that we have successfully completed 10 years of environmental review and can now focus on final design and construction of the new SR 99 tunnel beneath downtown Seattle.

Dan Mathis, FHWA’s Washington division administrator,
preparing to sign the SR 99 Alaskan Way Viaduct
Replacement Project’s Record of Decision
with Secretary of Transportation Paula Hammond.
So, what is a record of decision? In a nutshell, it’s federal approval of a project’s environmental review, and it describes the project the agencies have decided to build. A record of decision also includes any mitigation measures and commitments the project will need to implement. For the SR 99 tunnel, this list includes monitoring buildings and utilities during tunnel boring, replacing lost parking during construction and keeping neighbors and the public informed throughout the project.

The signed document set in motion a flurry of activities to get tunnel construction started. One of the first things we did was give our tunnel contractor, Seattle Tunnel Partners, the official notice to proceed with final design and construction. Seattle Tunnel Partners, along with boring machine manufacturer Hitachi Zosen, will begin work this fall.  When it opens in late 2015, the 1.7-mile-long tunnel will whisk traffic between Seattle’s SODO and South Lake Union neighborhoods.

Once open, the tunnel will also allow us to remove the final stretch of double-deck viaduct along Seattle’s downtown waterfront. The Alaskan Way Viaduct is vulnerable to collapse in a severe earthquake, which is why we’ve been working so diligently to make its replacement a reality. A project to replace nearly half of the viaduct with a new above-ground roadway is already under way south of downtown and is designed to eventually connect to the tunnel.