WSDOT just published that new video about working hyperbarically with the Highway 99 tunneling machine as it continues a maintenance stop before moving on to dig the final 25 percent of its 9,270-foot path – explaining, among other machines, that the machine is underwater as well as underground and is therefore something of “a submarine.” During the maintenance work that’s been under way since January 5th, crews have replaced 250 cutterhead tools, like these:
See the latest tunnel update here; the machine’s current location is shown here.
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