Fixing a 7,000-Ton Drill 101
An anonymous reader writes: At the end of last year, we discussed Bertha, the world's largest tunnel boring machine. During an effort to drill a viaduct beneath downtown Seattle, the machine — clocking in at 7,000 tons, 57.5 feet in diameter, and 326 feet long — got hamstrung by an 8-inch-diameter steel pipe. The complexity and scope of the repair plan rivals that of the project itself. "The rescue operation (workers call it "the intervention") began in late spring with construction on the shaft to reach Bertha. Workers have been sinking pilings in a ring to prevent the shaft from collapsing, using 24,000 cubic yards of concrete — enough for a medium-size office building. Once that ring is complete, digging on the shaft will start. When the shaft is ready, Bertha, which is damaged but still operational, will be turned back on so she can chew through the concrete pilings to reach the center of the shaft. There, the machine will rest on a cradle where workers can detach the front end and hoist it out." That detachable front end? It weighs about 2,000 tons by itself. The repair bill is estimated at about $125 million.
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Meanwhile the old one is still there blocking the path.
I don't think that they have much choice in this case but to fix the machine in place.
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Send a better Bertha that is able to bore through a boring machine.
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That chimp most definitely did not fall off a segway. It clearly saw that it was about to crash into some tree's/bushes and jumped off just prior to impact.
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It's like when you drill that important in the aluminum fixture you're working on, but then break off a tap in the hole while threading it. Now you've got a little bit of hardened tool steel stuck in the hole.
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Yeah, pretty much my exact first thought too... Even if it can only back up at a few dozen feet per hour, after a few days, it pops back out of the hole and they can work on it without a herculean effort.
For that matter, why can't they just drag it out? Connect it to a big-assed winch outside the tunnel, and pull. Certainly seems like a hell of a lot less work than building an access shaft.
Re:What a bunch of Luddites (Score:5, Informative)
The problem is that the drill head diameter is larger than the inside tunnel diameter. The tunnel gets built out of cast concrete sections which are installed behind the cutter head. You might be able to disconnect the cutter head and back the TBM out, but you still have the head to deal with.
I suspect that the complexity (that is, cost) of using a collapsible head would outweigh the potential benefits, especially since this is hardly a common occurrence.
BTW, a pretty neat animation of the project can be found here [youtube.com].
Re:it's because of homosexuality (Score:4, Informative)
Bad seals on the bearings and master bearing (Score:5, Interesting)
Actually, something else is causing the seals to fail on the bearings and master bearing. The sampling pipe was the original theory but it could not account for the damage being done.
FTFA “Contractors are not entirely sure what’s happening to the seals. They’re letting sand in, which is not good,” said Matt Preedy, deputy Highway 99 administrator for the state Department of Transportation (DOT). “Either you’ve got gaps somewhere, or you’ve got cracks in the seals.”
http://seattletimes.com/html/l... [seattletimes.com]
Basically, our water front soil make up is not ideal. Much of the Seattle water front is fill dirt from various late 19th century and early 20th century projects around Seattle. Much of the path Bertha is taking underground is lined with caissons to keep the liquid dirt at bay.
Re: Bad seals on the bearings and master bearing (Score:5, Informative)
And yet the University Link tunnel project is a half year ahead of schedule - the tunnels have been finished for a while, and the rails are already mostly in place.
Not every Seattle tunneling project has been a disaster.
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Indeed and I don't recall major problems with the bus tunnel and that train tunnel from a hundred years ago also went relatively smoothly.
The main reason that Bertha is having issues is that it's extreme engineering. Nobody has built a drill that size and the soil itself is quite challenging as well. The tunnel will be built and 30 years from now most people won't be thinking about how ugly the process was.
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The digging of the bus tunnel itself more or less went fine, as I recall. However there were some very stupid decisions made by Metro that led to the tunnel having to be closed for two years while they replaced the light rail tracks.
Note to anyone that didn't follow that saga - the bus tunnel, when built by Metro (the Seattle transit authority), had light rail track installed as a future-proofing and long term cost-saving move - but when the time came for Sound Transit to start running trains in the tunnel,
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Actually, something else is causing the seals to fail on the bearings and master bearing. The sampling pipe was the original theory but it could not account for the damage being done.
Even so, this shows what happens when you plan a one-shot operation with a single point of failure.
In this case, two: the drill itself and the seals. Either one means failure. When it's a one-shot operation with no provision for pause or repair, you're SOL. Fixable in this case? Yeah. For a fortune.
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125 million on a project like this is hardly a fortune.
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regardless to the size of the project 125 million is still a fortune.
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Strange mathematics given that this isn't a temporary project - it is an investment for the future of the city. When doing infrastructure projects one can't only think of the current situation but have to take the future into account. Most times infrastructure projects are founded by loans which means the costs are spread out over some generations of workers.
Huh? (Score:1)
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You are at least lucky enough to have tolls on the tunnel/bridge built. Here we have tolls on roads to build a railway tunnel.
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You are at least lucky enough to have tolls on the tunnel/bridge built. Here we have tolls on roads to build a railway tunnel.
What's wrong with that? A good railway system gets traffic off the road and thereby impoves the road for the people who need it. Transport systems are integrated.
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Except that the railroads already are in place, goes east-south while most tolls are on north-south, so the traffic will be the same as before, it won't attract more people to use the railroads since there aren't more people available to use it.
A political monument.
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Except that the railroads already are in place, goes east-south while most tolls are on north-south,
A railway network, much like a road network needs a lot more than just major routes, because people need to do more than just go from junction to junction. Anyway, it may well be a dumbass solution in this case, but the original point "it's bad to pay for rails with road tolls" is a poor one.
Re: The Republicans that rule this state... (Score:1)
This is sarcasm people--Washington is very much a blue state. When all these issues were brought up, state senate, house, and governor are all dem controlled.
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Never heard of Tim Eyman? He is a Republican, and he is the reason the mass transit here is so horrible and the roads are designed to prevent the poor from getting to work. This state is ruled 100% by Republicans. Even the socialist city council member here voted against raising the minimum wage. Even our socialists here act like Republicans.
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As a life long resident of WA, I can tell you that you're full of shit. WA is a purple state, the only reason why nobody notices is that it's slightly bluer than purple which means that most of the time the Governor and Senators wind up being Democrats. At the local level, it's much less dominated by Democrats.
Then again the GP is even more full of shit, so there you go.
Re: The Republicans that rule this state... (Score:5, Informative)
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Viaduct?? (Score:5, Informative)
>"During an effort to drill a viaduct beneath downtown Seattle"
Viaduct? How is digging/drilling a tunnel a viaduct? "A viaduct is a bridge composed of several small spans for crossing a valley or a gorge." http://en.wikipedia.org/wiki/V... [wikipedia.org] You cannot drill a viaduct.
They are digging a TUNNEL under Seattle for a car highway as an alternative to an old, damaged viaduct.
http://www.nytimes.com/2013/12... [nytimes.com]
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Except that recently, reading /. is like reading only the bottom comments in the /r/all subs at reddit. Reddit's voting system works better in filtering out bullshit, like the "Kill Yourself" coward above your post.
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Via = road
Duct = conduit.
Nothing implies above or below ground.
Though in this instance 'tunnel' would be a far more helpful description.
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dude, applying latin grammar rules to english doesn't make any sense.
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im+ply = in + fold
instance = urgent
Sorry, I can't understand what your saying about an urgent tunnel, a viaduct being an assembled road, and why nothing is in folds.
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Well, at least SOMEBODY got it.
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What if they dig the tunnel, then build a lifted "bridge" viaduct inside this tunnel? WHERE IS YOUR GOD NOW?
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>" What if they dig the tunnel, then build a lifted "bridge" viaduct inside this tunnel? WHERE IS YOUR GOD NOW?"
UG!!!! I can't handle such a possibility!
200 Years From Now... (Score:1)
Plasma digging robot trapped by ring of concrete pillars under Seattle.
Virtual tour (Score:5, Informative)
And if you enjoy crappy flash web cam software, you can watch the current progress on the cutter head replacement shaft here [wa.gov].
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Perhaps Sealttle should take a lesson from the Crossrail project in London. There has been 3 * 1 hour long TV progs about the building of the tunnels recently broadcast.
They were called "The Fifteen Billion Pound Railway".
As a Civil enginner and having worked on the Channel Tunnel, I was amazed at the progress that has been made since the late 1980's in tunnelling. The bits where they had to thread the TBM between existing tunnels at Tottenham Court Road was fantastic.
I'm sure the programmes are on the inte
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David Macauley [wikipedia.org] did this decades [socks-studio.com] ago.
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Re:Who foots the bill? (Score:4, Insightful)
The contractors are on the hook for the bill, not the taxpayers. No idea whether or not they have insurance that might or might not cover it.
Ignore the tea-baggers who are claiming this is a government failure. This one's all about how private industry isn't getting it done.
Ahem (Score:1)
Re: Ahem (Score:3)
The worst marketing job in the world... (Score:2)
...Must be having to sell boring machines. I would try to save the situation by going humorous, with an ad series starring Ben Stein.
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Why not buy another one? (Score:2)
Most of these TBMs are left in place in an isolation tunnel to rust away once they've finished a job. Why not just get another TBM and scrap this one? It seems like they're going through a lot of work when the TBM is probably only worth 20 to 40 million to fix it.
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Actually it will evolve into an intelligent boring machine, like Veeger did.
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http://www.popularmechanics.co... [popularmechanics.com]
They're spending $125 million to fix it. It seems plausible that dismantling it from behind and assembling a new one in place would have cost more than $45 million (plus $80 million for the new TBM).
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Assemble a new one and cut through the old one then. It seems strange that a 7000 ton machine that cost $45 mil gets taken out of action by a pipe. It would seem to me that they'd make it a bit more repairable than this. Oh well, more money, more delays.
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Someone explain to me how this is more cost-effective than drilling several smaller paths using smaller, more-proven equipment that costs a whole lot less both to buy and to repair? Seriously, I'd like to see the numbers.
Drilling through mud mixed with rocks. (Score:2)
It seems plausible that dismantling it from behind and assembling a new one in place would have cost more than $45 million (plus $80 million for the new TBM).
At first I wondered why they were going to sink a shaft and tunnel into it with the degraded-but-working machine. Why couldn't they just expand the tunnel behind the machine using less automated digging methods, then back the machine up into the room to get access to the front of the machine to repair it?
Then I looked a little deeper and discovered th
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Five city blocks (low-rise -- doesn't look to be anything over eight stories tall), a quarter-mile of the Alaska Way Viaduct, the entrance to the downtown ferry and water taxi docks, and two entrances to one of the larger docks at the Port of Seattle. If the tunnel is deeper than I think, or the soil is more liquid, add another seven city blocks (also low-rise), one park, the ferry docks themselves, part of the Port of Seattle dock, and maybe the football stadium.
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It's the contractors paying these bills, not the taxpayers. They signed a contract to get the job done. Doesn't matter that they broke their toys, they still have to do the work at the price they signed up for. This isn't a cost-plus gig.
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I'm wondering if this is an assumption on your part. I am a licensed civil engineer who worked for WSDOT many years ago and was often involved in writing contracts for roadway projects. Having no actual information about what the contract says I suggest that it is likely that there is a clause about encountering unexpected hazards and how additional pay would be calculated.....usually on a more or less cost plus basis.
Re: Oh, it's drilling alright (Score:2)
Except the pipe was not an unexpected hazard. It was noted in the contract and used by the people that did the initial survey...
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AIUI the ground is basically slurry. Even if you could back the machine out (which you probablly can't because the tunnel behind the machine is almost certainly smaller than the head of the machine) you'd just be leaving an unprotected face of slurry in front of you.
Idiot drill makers (Score:1)
Can't make your shit out of tungsten so when you hit a teensy 8-inch pipe you don't fuck the drill head up?
They should be asking for a refund on their drill head. I've blown apart 8-inch pipes with 10 inch coring bits and did NOTHING to the bit, which itself was about 1/8th the thickness of the pipes inner walls.
Mohs hardness scale, do you even, motherfuckers?
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Can't make your shit out of tungsten so when you hit a teensy 8-inch pipe you don't fuck the drill head up?
They should be asking for a refund on their drill head. I've blown apart 8-inch pipes with 10 inch coring bits and did NOTHING to the bit, which itself was about 1/8th the thickness of the pipes inner walls.
Mohs hardness scale, do you even, motherfuckers?
The cutting discs(Tungsten) and the head face(hardened steel) are hardened materials.
The the cutting face was not damaged at all AIUI. It was the hea