On 23.06.2016 Seattle Tunnel Partners (STP) with the SR 99 TBM Bertha, reached 940 m or one-third of the total bored tunnel length. So far they have installed 466 concrete tunnel rings. STP crews say almost half of their overall progress was accomplished in the past eight weeks, with more than 457 m of tunneling done since the last pit stop. They are now set to begin regular maintenance on the massive machine. The front end of the cutterhead is now located approximately 37 m beneath Spring Street, near Post Avenue. It will remain at that location for the planned inspections and maintenance which will last several weeks. Click here and us/69 for the tunnelbuilder archive. Visit http://www.wsdot.wa.gov/. 13/16.