The challenges of safely demolishing the Alaskan Way Viaduct in Seattle

SEATTLE-- In just days, demolition crews will begin tearing down the Alaskan Way Viaduct.

Section by section, the elevated highway that opened in the 1950's will be demolished.

Safely removing the double-decked highway is almost as challenging as building it. Demolishing the Viaduct will take about six months, with work starting at the Columbia Street on ramp and north of Pike Street.

From there, crews will focus on Columbia Street, taking down sections to the south and north.  They'll secure two to three block sections of viaduct at a time, average 30 days to tear down and clean up each section.

"As you go along and demolish the viaduct, there's different challenges in different areas," said Phil Wallas with Kiewit Infrastructure West, the company contracted for the $75 million demolition. "So each area presents its own challenge, and we have to have a different method for different areas."

Monitors will make sure noise and vibrations are kept within limits, and teams will spray down the demolition to control dust.

Part of the demolition will be nearly impossible to see, because it's happening underground. The Battery Street Tunnel, also considered an earthquake liability, will be filled with concrete and sealed.