Long-broken tunneling machine's cutter head hoisted out of Seattle pit

Reuters News
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Posted: Mar 30, 2015 7:51 PM

SEATTLE (Reuters) - The cutter head of the world's largest-diameter tunnel-boring machine was being hoisted out of a temporary pit in Seattle on Monday as construction crews work to fix a key component in a long-delayed multibillion-dollar highway replacement project.

The machine, nicknamed Bertha, overheated and stopped working in December 2013 after digging just 10 percent of a planned tunnel route to replace an ageing waterfront highway that hugs downtown Seattle, stalling a $3.1 billion roadway overhaul.

"Crews began lifting my 2,000-ton front end around noon today," the machine, which has its own Twitter account and some 15,000 followers, said in a tweet. "Still a long way to go before I'm on the ground."

The section being lifted on Monday includes the motors and parts that enable the cutter head to rotate, and it also houses the main bearing and seal system that will be replaced during repairs, the Washington state Department of Transportation said.

Lugging the machine's five-story-tall cutter head to the surface, a process expected to take 16 hours or more, is among unexpected construction delays that have sparked concern about cost overruns.

Seattle Tunnel Partners, the project contractor, said it hopes to have Bertha drilling again by August, though a new timeline for replacing the busy Alaskan Way Viaduct, damaged in a 2001 earthquake and nearing the end of its lifespan, is now 2017.

The project had initially been slated to cost $2 billion and be completed by 2015.

Critics of the project have begun drawing comparisons to Boston's "Big Dig," the country's costliest highway project, which took nearly a decade longer to complete than originally scheduled and was notorious for cost overruns, design flaws, worker fatalities and other problems.

Lawmakers in Olympia proposed scrapping the tunnel project and authorities have said portions of the Alaskan Way Viaduct and the earth around it have sunk as construction crews pump groundwater out of Bertha's area.

Repairs on the machine will take place just to the side of the highway that the tunnel will eventually replace.

(Reporting by Eric M. Johnson in Seattle)