No, not yet anyway. If they had used the name I suggested, though, instead of Bertha, there would never have been a problem.

Hard to believe this thing will not start again, if at all, for at least a year.

So far, it's just a big cork.

Mike McCann
MMC Engineering

BB....I think your first hunch might have been right!

Mike,

A 150' deep pit is needed to access the front of the tunneling machine to make the repairs.

A quick schedule from WSDOT at http://www.wsdot.wa.gov/Projects/Viaduct/Contents/...
• Late May: Begin building the access pit’s underground walls.
• Late July through September: Excavate the pit.
• October: Remove the machine’s cutterhead and begin repairing damage to the seal system and main bearing.
• February 2015: Test machine to ensure it is ready to tunnel beneath downtown.
• Late March 2015: Resume tunneling.

More information about the project at http://www.wsdot.wa.gov/Projects/Viaduct/

What's incredulous to me is that they intend to charge $125MM to repair an $80MM machine. Presumably, one could contract a scrap metal outfit to come in and cut it up and remove it, receive X amount of money in return for the scrap yield, and be further ahead ordering a new machine ?!?! Hard to speculate not knowing the whole situation but it certainly seems like opportunism. I'll be in Seattle in a couple of weeks so it will interesting to hear the local scuttlebutt.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

Ron:

The thing did not find any gators, but was stopped by a Gooeyduck.

Mike McCann
MMC Engineering

"What's incredulous to me is that they intend to charge $125MM to repair an $80MM machine. Presumably, one could contract a scrap metal outfit to come in and cut it up and remove it, receive X amount of money in return for the scrap yield, and be further ahead ordering a new machine ?!?!"

The cost of repair is not simply the cost of the labor and materials for the repair itself. In order to get access to the machine a rather sizable hole has to dug, which requires reinforcements, etc., etc.; the hole to be dug is about 80 ft in diameter and 80 ft deep, but pilings have to be driven down to keep the hole from collapsing, and retaining walls need to constructed to keep water out. Additionally, the delay of the project itself incurs cost; people get laid off and rehired, plus critical personnel are put on retainer, plus cost of money for a extra year. It's likely that there is no spare seal, and a new one has to be made. That, in itself, is probably not particularly expensive, but the dismantling of the machine to get to the seal, installation of the seal, re-assembly of the machine, testing, etc., are probably the cost driver for the machine repair itself.

The machine itself is unique, building a new one probably incurs a 1 year delay all on its own, and probably will cost more than the original machine. Even if a new is built, the old one will need to be removed from the tunnel, which presumably incurs a large cost of its own; if that part were easy, that would probably have been the approach for the repair itself. I would guess the cost of the actual repair to be on the order of $10M to $30M, and the rest to be attributed to the stuff mentioned above. Note also, that the assembly of the machine when received took about 3-5 months, and while the repair of the machine doesn't require a complete assembly, it's a disassembly/assembly, so possibly 4 months just for that and the testing afterwards.

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Well, IR, according to the state contract, the contractor's consortium is\ on the hook for the repairs, and any delay time in the project due to the delays. Technically, Washington taxpayers should not be on the hook for this. That remains to be seen, however, as this will undoubted wind up in litigation, if it is ever completed.

I have been following this fiasco for over three years now, and besides the political and ecological football of the existing viaduct which the tunnel is supposed to replace, I have found the boring machine issue to be very boring.

Personally, I think they should just purchase a few anti-gravity machines, strategically place them around the viaduct supports, and sell tickets to tourists to view the boring machine from the 150 foot shaft. Tourists will buy tickets to see anything. If enough tourists enter the tunnel, we could just pull up the ladder, fill it up with concrete, and create a national monument to political fiascos.

Mike McCann
MMC Engineering

I don't doubt that's the position of the state, of course. Nevertheless, the cost is still real and still to be incurred by someone. If this winds up in court, the cost will simply escalate and further delay the project. From what I've read, the pipes that started this immediate situation are pipes left there be a contractor for the state, so the state has some 'splaining to do before it attempts to pin this all on the digger.

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Yep.

The pipe did cause it to stop, and someone did forget to remove it, who I can't remember, but the overheating of the bearings is another issue here, possibly connected, possibly not to the pipe issue, and that is why it is shut down now pending any repairs.

Mike McCann
MMC Engineering

The pipes were known obstructions, according to the state DOT, and their approx. locations were part of the original RFP package to the contractor(s). I'm fairly surprised that a steel well casing or piling or whatever could not be drilled, when rocks could.

Mike...we have gators in our sewers that would try to tackle the boring machine

I'm guessing the well casing/ whatever was made of steel, and tough enough and ductile enough to get wrapped around the cutter head like fishing line around a propeller.


I wonder if it would be safe to back up the TBM while deconstructing the ~1000 feet of tunnel liner behind it, and servicing the cutter head at the original entry face. It sounds cheaper than excavating a cutter head sized well for access.

Mike Halloran
Pembroke Pines, FL, USA

Knowing the material they are excavating, that would be very dangerous Mike.

Mike McCann
MMC Engineering

I've wondered about that, i.e., backing up. I would assume that given the scrutiny that this project is now receiving, that option had to have been evaluated, and for whatever reason, deemed to be less viable than digging the new hole down to the cutter.

The obvious analysis of alternatives should have included:
> back the dang thing up, fix it, and run it back in
> presumably building a new one would require the previous alternative, and if that could have been done, a new borer would be superfluous
> dig a hole down to the borer head and repair in situ.

Which raises a question. What I read implies that the cutters themselves had been damaged by the pipe and replaced. So, how was that done? I assume that there was some method of doing that without a major effort, since that must be a probable thing to happen during a 4-yr dig. A bearing/seal, on the other hand, was apparently not expected to have be replaced.

As for the cutting heads, cutting what is likely to be sedimentary rock, which is essentially sandstone or limestone, is a different thing than going against hardened steel piping. That's probably more like immovable object versus unstoppable force. The pipe won, which I don't think should be that surprising.

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Any chance of starting another boring machine at the other end of the tunnel and working back toward the broken one, then removing both when old one repaired?

Thank-you irstuff for your detailed and simplistic explanation of the obvious. I do appreciate you not using any big words. Having worked with machinery of one type or another for the past four decades, the concept of incidental tasks and costs had completely escaped my understanding until just then. Always a pleasure to converse with people who are quick and ready to explore ideas.

Sorry about that, my "sarcasm" key has been sticky lately, I'll have to have IT look at that.

It is better to have enough ideas for some of them to be wrong, than to be always right by having no ideas at all.

That is one of the risks of interacting with people in forums or topics such as this

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Ron:

These machines take years to build, get on site and operating. Also, they do not have a reverse. They only can move forward. Great foresite, huh?

Mike McCann
MMC Engineering

An article from 2010; seems like the writer had a crystal ball. Also not the first time this has happened in the area, although not on the same scale.

http://www.thestranger.com/seattle/what-could-poss...

The article nicely explains why the machine can't back up.

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I wonder if they could do some soil grouting behind the TBM, remove some lining, then back the machine up? Just a harebrained idea.

Now I'm getting the impression that what they were tunneling through is not monolithic rock, but dirt with rocks in it. I.e., if you remove a segment of tunnel liner behind the machine, the roof will cave in, and the dirt will keep pouring in until the tunnel fills or until the resulting cavity reaches the surface. Dangerous, indeed.

Also, because it's the largest such machine ever built, they can't just buy a used one, or parts of one, from somewhere else.

I wonder if they could leave it where it is, buy two (used?) TBMs of ~half the size, and drive two smaller tunnels instead of one big one?

Doesn't matter, really. It smells like the dispute over cost overruns, from estimates based entirely on fantasy, with local and state politicians trying so hard to screw each other, will spend decades in court.

Mike Halloran
Pembroke Pines, FL, USA

You got it Mike. Part of the reason we have so many problems with landslides here - locally unstable glacial till soils.

Mike McCann
MMC Engineering

Ron:
"Any chance of starting another boring machine at the other end of the tunnel and working back toward the broken one, then removing both when old one repaired?"

Great, now we have two machines stuck... the tunnel isn't really needed... matter of filling the void with CLSM or something and forgetting about it...

Dik

"I'm guessing the well casing/ whatever was made of steel, and tough enough and ductile enough to get wrapped around the cutter head like fishing line around a propeller."

Can't disagree, Mike, but the point is/was that the bore path was known to intersect a number of these casings (18 or so if I remember right), the casings were left by borehole wells made by the state DOT for soil/rock sampling. Point being, if you knew the casings were in the way, would you not have designed/programmed the cutter head to manage them?

The surrounding earth being drilled is mostly compacted mud/clay and glacia "till" (mixed gravel and mud). Oh, and below sea level in a wet climate, so really wet too. Pretty much guaranteed to collapse unless you seal it. So, whent the seal failed...well, now we have a driller head buried up to its figurative armpits in mud.

Was there ever any mention if this was the first casing encountered?

Mike McCann
MMC Engineering

Ya know, following the 1989 earth quake, San Francisco just took down their equivalent of the Alaska Way viaduct and didn't replace it with anything. Seems to have turned out ok.

Yeah, but that section was relatively short, and in both directions, the traffic is pretty messy these days.

Nevertheless, whatever the problems there, they pale in comparison to the southbound 80 to Bay Bridge transition, which, on, say, Friday nights, can take a couple of hours or more to get through to the city. I once decided to head down to the San Mateo bridge to cross the Bay, just to avoid the Bay Bridge. The Bay Bridge seems to do little relieve the congestion on the approaches.

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