WSDOT moves forward on Alaskan Way tunnel

The Federal Highway Administration signed a record of decision on Tuesday allowing the Washington State Department of Transportation (WSDOT) to begin final design and construction of the 1.7mile (2.7km) tunnel beneath downtown Seattle.

Following issuance of the record of decision, WSDOT directed Seattle Tunnel Partners (STP), a joint venture of Dragados USA and Tutor Perini, to begin work on the second phase of its USD1.35bn design-build contract for the 57ft (17m) diameter bored tunnel.

Initial construction activities, such as utility relocation, and final design and manufacturing of the Hitachi Zosen TBM will begin this fall. The SR 99 tunnel is projected to open in late 2015.

“After more than a decade, we are moving forward to replace the Alaskan Way Viaduct,” Washington governor Chris Gregoire said. “Now that the tunnel has approval from the Federal Highway Administration, we can kick off the next phase of its design and construction.”