Bertha insurance snafu and yet another stop under Seattle
A contractor almost found itself without any Bertha insurance this week, but that didn’t stop the world’s largest boring machine. Bertha actually stopped itself.
The Seattle Times reports that the contractor who is operating the machine originally only had insurance until Aug. 31. That was the day the new SR 99 tunnel through Seattle was suppose to be completed.
But as the insurance was about to run out this summer, it was extended to Oct. 10. A new Bertha insurance plan is needed, and is expected to be worked out before the extension expires.
Bertha is currently stopped about 170 feet below First Avenue and Union Street, again, for maintenance. It is the third time the machine has stopped for inspections of its cutterhead — the first was shortly after it resumed boring around the new year, then in June. The purpose of the maintenance is to replace cutter tools at the front of the machine. These are larger than tools replaced in the past — they can weigh up to 600 pounds. The current medium that Bertha is digging through is sand and gravel — it was previously in predominantly clay. That sand and gravel wears down the tools faster.
Unlike previous stops, crews are not required to go into a hyperbaric chamber to do the work. Previous maintenance required people to go into an environment with much higher air pressure.