Intense planning is underway regarding how to safely demolish the 1.4-mile concrete double-decker Alaskan Way Viaduct, beginning in February. Around that time, the Washington State Dept. of Transportation (WSDOT) plans a grand opening of a two-mile bored tunnel under downtown Seattle, a piece of the $3.3-billion project with the goal of replacing the viaduct.
The six-month, $93.7-million demolition of the seismically vulnerable viaduct, opened in 1953, won’t look that different from any other double-decker project, says Dan Hemenway, project director with Kiewit Infrastructure West Co., which leads the design-build team doing the job. “What makes this unique is the close proximity of the buildings and the massive grids of utilities we are going to be protecting,” he says. “We will have two to three blocks secured off at a time, and have 30 days to get in, do the work and get out.”