SR 99 TBM reaches halfway point
14 October 2016United States - The TBM mining the Alaskan Way Viaduct Replacement Tunnel passed beyond the halfway mark of a 9,270ft (2,825.5m) tunnel on September 30, the Washington State Department of Transportation announced October 3.
Seattle Tunnel Partners has now excavated more than 4,635ft (1,412.8m) of the SR 99 tunnel, with much of that progress occurred during the past five months. STP tunnelled more than 3,000ft (914m) since leaving a planned maintenance stop on April 29 to begin the push beneath the viaduct.
The TBM is now about 190ft below the surface and will undergo a brief planned maintenance stop. WSDOT said the 90ft- (27.4m-) deep receiving pit at the north end of downtown Seattle is largely complete, along with many other aspects of the tunnel portals. Although future contractors will make final connections to the highway, several of the ramps and roadways into and out of the tunnel are already in place, along with tunnel operations buildings at each of the portals.
