Seattle tunnel machine seal damage discovered

SEATTLE – Crews have found damage in the seal system that protects the core components of the world’s largest tunneling machine, and officials said Friday they’re still assessing the best way to get the machine helping build a new highway tunnel under Seattle moving again.

It’s unclear when operations can resume. The machine has been mostly idle for two months, raising increased concerns that the troubled project will bust its $1.4 billion state budget. The total viaduct replacement is estimated to be a $3.1 billion project.

The machine, nicknamed “Bertha,” is only one-tenth of the way toward completing a 1.7-mile tunnel. The tunnel will carry state Highway 99 traffic and allow the removal of the aging Alaskan Way Viaduct along the Seattle waterfront.

On Friday, the state Department of Transportation said inspections conducted last month found that many of the cutter-head openings were clogged with dirt and other things. In a statement, state transportation officials said that late last month they also discovered the seal system protecting Bertha’s main bearing was damaged. This was revealed after “higher-than-normal heat sensor readings” appeared.

“The main bearing is what allows the cutter head to spin,” the statement said, adding that tunnel contractor and experts are working with the machine’s manufacturer to try to figure out how to fix the problem.