Saturday’s second lift from the access pit is one of four planned to bring the giant Highway 99 tunneling machine’s front end to the surface for repair work expected to be finished by late summer.
Workers have lifted the second shell piece of tunnel machine Bertha from a 120-foot-deep access vault to the surface as Seattle Tunnel Partners embarks on months of repairs and strengthening work.
The lift, of less than 100 tons from the machine’s left side, happened around 6 p.m. Saturday. It follows a 270-ton hoist of the upper shell on Thursday.
One more 90-ton shell piece will be removed from the right side soon, said Todd Trepanier, state Highway 99 tunnel administrator.
That lift will be followed in perhaps a couple of weeks by the 4 million-pound cluster that includes the bearing block, ring-shaped drive axle and the 57-foot-diameter cutting face.
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The cutter unit, to be exhumed by a custom-built modular lift tower, will be laid near the Alaskan Way Viaduct and dismantled. Hitachi-Zosen, which built the $80 million machine, will replace the bearing and the bearing seals, which were ruined by incoming grit in early December 2013. Extra steel will be fastened to stiffen the front of the machine and reinforce the bearing parts.
Bertha is expected to resume digging in late summer, continuing toward South Lake Union. The tunnel is now forecast to open in late 2017 at a cost of $2 billion, plus whatever overruns wind up being borne by the Washington State Department of Transportation.