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Bertha, the tunnel boring machine digging the State Route 99 tunnel has been underground for more than three years, but it finally looks like it’s entering the home stretch.
A project update posted late Wednesday by WSDOT says that with less than 1,000 feet to go, mining has been temporarily paused so crews can make sure the machine is tunneling in the right direction. Seattle Tunnel Partners, the contractor managing the project, estimates that digging will resume next week.
The update notes that adjustments are “common,” and that a similar adjustment happened when crews mined down to repair the machine.
The project, originally estimated to be ready for traffic by December 2015, has been plagued by delays. According to current project schedules, Bertha should reach the end of its journey around May of this year. WSDOT estimates that on that timeline, the tunnel should be ready for traffic in early 2019.
So far, the boring machine has traveled 8,310 feet, and successfully mined underneath the last building in its path last week. The cutterhead’s current location is somewhere around Sixth Avenue and Denny Way.
Ultimately, the tunnel will replace the Alaskan Way Viaduct, which was damaged in the 2001 Nisqually quake. The viaduct is closing for its semiannual maintenance this weekend.