Commissioning of the SR 99 tunneling machine continues as Seattle Tunnel Partners (STP) prepares to resume mining, the Washington State Department of Transportation report on Nov. 24. STP began testing machine components earlier this month as crews continued welding pieces and reconnecting hoses and cables. Last week, STP began rotating the machine’s cutterhead a few degrees at a time, stopping periodically to take measurements before completing a full rotation.
Tuesday, Nov. 24 marked the first sustained rotation of the cutterhead since the machine broke through the southern wall of the access pit on Feb. 19. STP indicated they will rotate the cutterhead in both directions for about one hour at a time. Watch a short video of the cutterhead rotating below.
During the next phase of commissioning, STP will backfill the access pit with sand and gravel to prepare the machine for mining. STP’s most recent schedule shows that the machine will be ready to resume mining on Dec. 23.