SEATTLE, Wash. - A week into specialized inspections of the stalled tunnel machine named Bertha - and there's no clear answer as to why it's stuck.
Workers inspecting the machine's pressurized excavation chamber have spent about 90 hours doing hyperbaric interventions.
They found a chunk of rock or concrete, a PVC pipe and parts of a steel well casing Bertha chewed through in December.
Project leaders say so far none of it amounts to a smoking gun as to why the machine is stuck.
"Nothing really substantial that would lead you to believe there was a specific cause," is how Matt Preedy, of the Washington State Department of Transportation, described the findings Friday.
Preedy says although warning lights went off when Bertha met resistance in early December, in general the machine is in working order.
That raises questions of a design problem with Bertha.
"I can't speculate on that," Preedy said. "The inspection is not done and it would really be irresponsible of me to try to speculate."
Representatives from Bertha's manufacturer in Japan are now helping with the investigation.
The state has brought in outside tunnel experts to review Bertha's problems.
There's no estimate for when the inspections will be complete or when tunneling might resume.