Bertha, the SR 99 tunneling machine, is now tunneling in Seattle soil after breaking through the access pit wall late Jan. 6. Seattle Tunnel Partners (STP), the lead contractor, has mined 73 feet and installed 12 concrete tunnel rings since Bertha first moved forward in the pit on Dec. 22 after being repaired.The tunneling machine is expected to reach a planned underground maintenance stop in late January. Once there, crews will spend three weeks performing final maintenance before the machine tunnels beneath the Alaskan Way Viaduct.With excavation underway again, STP is resuming its operation for removing excavated material from the
