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Seattle's Behemoth Boring Machine, Idle Since 2013, Makes Some Progress
After being blocked by an obstruction ("the object") which left it idle just over two years ago, repair work has continued on Bertha, Seattle's enormous tunnel-boring machine. Now, reports KOMO News and The Seattle Times, Bertha is once again ready to work. From The Times' coverage:
Tuesday morning's push of one and a half feet provided Seattle Tunnel Partners (STP) enough space behind Bertha’s drive motors to fasten the next concrete ring at the 1,085-foot mark of the planned 9,270-foot tube. Chris Dixon, STP project manager, is calling this a testing phase. The team is measuring how Bertha responds while rotating through heavy loads of compacted sand. Last week, a fixed steel arm in the front end broke and needed a one-day repair. ... This week’s two-day push would leave the nose of the drill just short of the north edge of the concrete vault, dug in 2014 so STP could reach and lift the 4million-pound front end for repairs. The winning bid from STP called for the tunnel to be completed this month.
Boring.
Well, I guess if it hasn't done anything since 2013 it is certainly a machine capable of boring even a behemoth!
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Another boring story on slashdot.
Yes. But the path of the tunnel runs through what is essentially an old land fill. So the machine should have been designed to deal with old steam boilers, scrap iron, chunks of concrete/rebar, etc.
Have gnu, will travel.
Another boring story on slashdot.
You know the drill..
This does not augur well for the New Year.
John
Rock crumbles, is brittle, and has a low tensile strength even though the compressive strength is high. The sort of steel used for a pipe is none of those things.
See also stuff designed for "soft rock" suddenly hitting Basalt.
Rock is more brittle than steel. Hit rock with a hard enough cutter blade, pushing with enough force, and you will chip away at it. Hit a malleable and tough steel pipe with the same cutter blade and the same amount of force, and the blade may dig in to the steel and get caught in it.
The operator doesn't exactly have visibility into the obstruction, so when progress stops, he may not recognize what's going wrong. He can add more force in an attempt to break through. Add enough force and something will eventually give, but there's no guarantee if it will be the obstruction that gives way, or the engine, or the power train, or the frame of his machine.
And what kinds of sensors do you think you can deploy on the face of a giant cutting disk that will survive the thousands of horsepower of force mashing it into the earth? (Trick question, the answer is none.) About all they can effectively monitor is from the back side of the cutting face. That means indirect measurements only, like the amount of power, rotational speed, rate of travel, temperature of the cutting face, sound of the cutting face, and the composition of the tailings. It's not exactly like looking out the windshield and seeing you're about to drive into a big steel pipe. The amount of power is regulated by the operator, but what are his options when it stops going forward? It's not like he can back up and turn left to go around it. He can pretty much decide "add power" or "stay stuck".
John
Seattle consistently ranks in the top three US cities on a whole host of criteria, and has the second-highest percentage of the population with graduate degrees (after San Francisco), so probably not exactly the stupidest motherfuckers on Earth.
Have you ever been to San Antonio, Orlando, Louisville or Tampa?
But the traffic sucks. They should build a tunnel or something.
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
Seattle taxpayers are not paying for this project, except insofar as they are taxpayers to the State and the Feds, which are. "Local" funding is a small percentage of the $3 billion project. Further:
1. I-5 is a parking lot. Traffic congestion in Seattle is 5th worse in the nation.
2. The current Alaskan Way Viaduct is an ugly concrete behemoth.
3. The current Alaskan Way Viaduct is going to fall down.
4. The current Alaskan Way Viaduct carries 110,000 vehicles a day.
5. We can all ride bicycles because the city has closed one entire lane of most downtown streets to accommodate it.
How about a moderation of -1 pedantic.
And maybe, just maybe they'll come away with some lessons learned form this kabillion dollar, 0.5mph joyride.
Maybe one of those lessons is "there are risks when you try to save money by pushing the boundaries with new, untested drilling technology".
Meanwhile the tunnels Sound Transit has been recently digging in Seattle, following ho-hum old smaller bore twin-tunnel principles, are going well - they're under budget and ahead of schedule. I am really looking forward to taking light rail to UW in a month or two! No more sitting on a bus that's stuck in traffic gridlock...
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