(UPDATED 9:36 PM WITH PHOTOS FROM TOUR TODAY)
ORIGINAL REPORT, 4:26 PM: Since its last maintenance stop ended in mid-July, the Highway 99 tunneling machine has dug 1,000 feet. Another 500, and it will be at the official halfway mark. But right now, WSDOT says, the machine is stopped down “to inspect and replace some of the larger cutterhead tools on the front end … STP chose to check the tools â€“ and change them as needed â€“ because Bertha has moved from clay into a mixture of sand and gravel that will more quickly wear them down. Replacing the tools now will preserve the machine and ensure it continues to function well as it mines toward STPâ€™s next planned maintenance stop.” You can read the full update here, and you can go here to see where the machine is now – that’s also the page that tracks its progress, currently listed as 4,135 feet along the planned 9,270-foot tunneling route.
ADDED 9:36 PM: A West Seattleite who has long represented our area on Viaduct/Tunnel advisory groups, Vlad Oustimovitch, is sharing photos tonight from a tunnel-project tour earlier today. First photo shows a used drilling tooth that was replaced today, as part of the work mentioned above:
Next, you’re looking at “giant rollers” that hold up the tunnel-building part of the machine:
Here are the pistons that push the machine forward once rings are in place:
Another view from inside the tunneling machine:
Here’s the control room:
And “the tail end” of the machine:
Back outside the machine, in the already-built 4,135 feet of tunnel, here’s a look at the upper deck:
Oustimovitch was one of “about eight” people on today’s tour.