Seattle Tunnel Partners has begun installing a new main bearing on the SR 99 TBM with a view to restarting tunnelling next November. Tunnelling will take a year to complete, with the tunnel now scheduled to open to drivers in Spring, 2018. STP and manufacturer Hitachi Zosen will perform an extended series of tests to ensure the machine is up to standard.

STP has fully assessed the disassembled machine parts and made significant repairs and enhancements. In addition to beginning installation of the main bearing, STP crews have installed portions of the new seal system that will protect the bearing. Modifications include the addition of reinforcing steel, new monitoring systems and upgrades to the soil-conditioning system to prevent clogging. 

While the machine has been under repair, STP has continued essential work at the future tunnel portals, including construction of ramp and highway connections, and the buildings that will house tunnel operations. 

STP crews halted tunnelling in December, 2013 after the machine overheated. After an investigation, they discovered damage to the seal system and decided it needed to be replaced along with the main bearing. The cause of the damage has not been determined. Responsibility for costs associated with the delay will be assessed through the process outlined in the tunnel contract.

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