How will the tunneling machine be repaired?

Tags: sr99

In mid-April, Seattle Tunnel Partners provided WSDOT with a schedule that outlines the necessary steps for repairing the SR 99 tunneling machine and resuming tunneling by the end of March 2015.

Seattle Tunnel Partners is building a 120-foot-deep circular pit (pdf 2.5 Mb) in front of the machine, which is located about 60 feet below the surface in a fenced off construction zone between South Jackson and South Main streets. When the pit is complete, the machine will tunnel forward into it. Crews will then partially disassemble the machine and make repairs and enhancements. Seattle Tunnel Partners' work plan (pdf 4.8 Mb), which is illustrated in an animation (view on YouTube or download WMV file), contains four major repair and enhancement elements:

  • Replacing the damaged seal system with a more robust system
  • Replacing the main bearing
  • Installing enhanced monitoring systems
  • Adding steel to strengthen the machine and accommodate the new seal system


You can watch crews work via our construction cameras.