Bertha fix will likely require big access shaft

Final repair plans are weeks away, but the tunnel contractor is hoping to access and repair the machine's bearing seals from above ground.
Big Bertha

Big Bertha Photo: WSDOT

The plan to fix Bertha probably won’t be finalized before the end of the month, but Seattle Tunnel Partners is making arrangements to unearth the idled boring machine.

STP, the Highway 99 Tunnel Project’s lead contractor, is working closely with Bertha’s manufacturer, Hitachi Zosen Corp., to determine the fastest way to get at and replace a set of five damaged seals that protect the machine’s main bearing. The seals are located behind Bertha’s 57.5-foot-diameter “cutter-head,” which, along with the rest of the machine, sits idle some 60-feet beneath Pioneer Square, near South Main Street.

The contractor has been in touch with companies that would help with accessing and working on the machine from above ground, via a shaft. Reaching the bearing assembly from inside the machine is possible but complex, and would require removing a large number of parts. “It’s looking fairly certain that a shaft is going to be the preferred option,” Seattle Tunnel Partners project manager Chris Dixon told reporters on Friday. 

While the exact shaft requirements are not definite, Dixon said the rectangular hole would likely be about 80 feet wide and extend some 20 to 30 feet in front of Bertha’s cutter-head. To reach all the way to the bottom of the roughly five-story boring rig, the shaft would need to be around 120-feet deep. 

To keep the surrounding gravelly soil from collapsing, and water from Elliott Bay and groundwater from flowing into the work area, the shaft will be walled on three or four sides. If the contractor chooses the four-walled option, operators will drive the ailing machine forward slightly to break through the side closest to the cutter-head.

Dixon said that Seattle Tunnel Partners staff would meet with the firm Brierley Associates on Tuesday to discuss the shaft’s design. Brierley specializes in underground engineering. The two companies haven’t yet signed a contract for any shaft work.

Hitachi Zosen hasn’t confirmed whether fixing the bearing seals will involve removing Bertha’s 745-ton cutter-head, which weighs the same as about seven locomotives. Seattle Tunnel Partners has contacted Barnhart Crane & Rigging, the company that assembled Bertha last year. For the assembly, Barnhart used a “modular lift tower,” which relies on hydraulic jacks to pick-up and rotate objects weighing up to 1,000 tons. Dixon said it’s possible that the tower could be used for the upcoming repairs, but that a large crane might also suffice.

In Japan, where Bertha was manufactured, Hitachi Zosen has assembled a task force that is looking to remedy the machine’s problems. In recent weeks Hitachi Zosen had as many as 30 employees, including principals, here in Seattle. Three Seattle Tunnel Partners staff members are now in Japan working with the task force. One of the STP employees was in Japan while the machine was manufactured; another is a project manager who has worked on the Highway 99 Tunnel Project since 2010. 

Hitachi Zosen is also coordinating with Rothe Erde, the company that manufactured Bertha's bearing, to ensure that the part was not compromised when the seals failed. The bearing allows Bertha’s cutter-head to spin. If it is damaged, there is a spare on standby in Europe. Preliminary inspections by Seattle Tunnel Partners indicate that the bearing is still in good shape. 

Washington State Department of Transportation officials said that the access shaft should not weaken the nearby Alaskan Way Viaduct. David Sowers, WSDOT Engineering Manager, allowed that one of the viaduct's support columns did sink about .2 of an inch earlier in the project as water was pumped from underground. but he added that the “the viaduct is certainly stable.” The agency is monitoring the ground around the overpass.

WSDOT and Seattle Tunnel Partners continue to say that it's too early to know how long the repairs will take, or how the delay will affect the project’s overall schedule or budget. Dixon did say last Tuesday that it could still be possible to finish digging the tunnel, as scheduled, around Sept. 30. The machine is about 1,000 feet into the roughly 9,000-foot (1.7-mile) tunnel path, which will end in South Lake Union. Until Bertha makes it to 1,300 feet, Seattle Tunnel Partners do not have to pay Hitachi Zosen the last 10 percent of the machine’s nearly $90 million pricetag.

Bill Lucia writes about Seattle City Hall and politics for Crosscut. He can be reached at and you can follow him on Twitter @bill_lucia.

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Posted Sun, Feb 16, 9:33 a.m. Inappropriate

If they get everything fixed this time, but then there are more problems another 1000 feet down the tunnel, will we be able to dig more shafts? Is the soil going to be any different the rest of the way such that this doesn't happen again?


Posted Tue, Feb 25, 6:25 p.m. Inappropriate

Just call us "Shaft City".

Posted Sun, Feb 16, 1:34 p.m. Inappropriate


Yes, the soil will change. In fact, they were only around 500 feet or less from getting out of the wet loose material. From statements made, that was the root cause, wet material getting past the seals.

I would expect a shaft 100 foot x 100 foot to give working clearances around the head as it comes out of the shaft. The shaft will be sunk past the base at least five feet probably around ten to fifteen feet past the base. This would allow a CDF (Controlled Density Fill) base to be placed allowing a decent spot to work and place manlifts in the hole. An 80-foot hole is small and 100-foot hole is not that much more expensive nor is it much larger of a footprint. Driving piling is not that big of a deal, (just pull them so the head does not get messed up again.)

If this were not a WSDOT job, it would be no big deal, and just part of the job. Although, I would hate to be Hitachi Heavy Industries right now. They still own the machine for another couple of hundred feet. WSDOT make for more scary headlines and everybody is all atwitter now. In reality it is just another day on the job.

Posted Sun, Feb 16, 6:19 p.m. Inappropriate

Another reason to take this job away from any control by WSDOT.

Either terminate the project or terminate WSDOT.

Posted Sun, Feb 16, 11:54 p.m. Inappropriate

You make me laugh commonsense. The job in fact is STP's, remember? It is a design build project which means that STP a joint venture between Dragados, one of the most experienced tunnel contractor in the world and Tutor Perrini is the one doing the work.

There is no reason to terminate the job.


Posted Wed, Feb 19, 7:57 p.m. Inappropriate

I wish you made me laugh, abc. Unfortunately I think you're being paid to be a shill.

Posted Wed, Feb 19, 10:22 a.m. Inappropriate


Who are you? Do you have any expertise in construction which suggest that we listen to you?

Posted Sun, Feb 16, 7:15 p.m. Inappropriate

It's not too late to abandon the machine and leave it as a curiousity on the Seattle Underground tour.

But, when do the abovegound options cost less and make this tunnel the wrong economic decision?

Posted Sun, Feb 16, 8:18 p.m. Inappropriate

This tunnel was always the wrong economic decision. It was purely an "aesthetic" decision -- the powers that be in downtown Seattle hate the viaduct and want it removed, no matter what the cost. The public clearly preferred a new or rebuilt viaduct over any of the other choices, but the public was not allowed to vote on this.

The deep bored tunnel is just a very stupid, very expensive mistake, even if there had been no problems constructing it.


Posted Sun, Feb 16, 11:56 p.m. Inappropriate

Yes it is, the contracts have been signed, the tunnel has been engineered and designed and a significant amount of the construction is underway.

FYI: No one with any authority is considering abandoning this project.


Posted Mon, Feb 17, 8:46 a.m. Inappropriate

When is the project overbudget enough to pull the plug on? If it is estimated at 4 billion, is 6 billion too much? Are you saying that now that work has begun, the money will flow no matter what the cost? That sounds like the difinition of insane decision making to me.

Why's there all that water in the ground where it's at, what's the seawall for?

Posted Mon, Feb 17, 9:42 a.m. Inappropriate

Good Lord, do you really think that leaky old seawall is holding back the entire ocean? It's got enough to do trying to hold up the viaduct and Alaskan Way. The whole waterfront area is like a big sponge (made of loosely consolidated debris from the early days of Seattle) that seawater flows freely in and out of.

Of course there comes a time when the cost of starting over becomes less than the cost on continuing, but we ain't there yet. Starting over would require all new environmental documents, engineering, and negotiations with stakeholders, as well as ripping up a lot of infrastructure already built. Then more billions for the new solution. As it stands, Hitachi is on the hook for these fixes. The state only eats the cost of delay--and there will be delay. I wish they'd stop saying it might still get done on time.


Posted Mon, Feb 17, 10:05 a.m. Inappropriate

If it is a big sponge, I hope the tunnel is up to seismic standards for critical infrastructure and that the USGS earthquake experts have vetted it.

If the integrity of information is anything like that of the 787 or Fukushima plant, all estimates are off. I'll project 2017 at 16 billion. That should give them something to beat.

Posted Mon, Feb 17, 11:57 a.m. Inappropriate

I'd imagine that groundwater is more of a problem than seawater at that depth.


Posted Mon, Feb 17, 1:32 p.m. Inappropriate

jen27, why should Hitachi be on the hook for any of these costs if the wrong blade was selected by WSDOT in the first place? Did Hitachi have a hand in that decision? That seems very unlikely.

Posted Mon, Feb 17, 3:23 p.m. Inappropriate

One WSDOT didnt' select the wrong blade. Those decisions are made by the tunnel contractor STP,

Two, the tools on cutter head likely have nothing to do with it. That is a red herring if there ever was one. STP exchanged the cutter wheels tools on the cutter head with "ripper tools" FYI, the original setup had half and half of each. STP decided that they could do the job more effectively with all rippers.

Three, I doubt that STP didn't consult Hitachi before swapping them out. Each one of those cutting wheel or ripper tools costs thousands of dollars each and weigh hundreds of pounds. They are made specially for Bertha and from very hard steel and take hours to swap. They didn't do it on a whim.

Four, the cutter wheels are designed to break apart boulders like a glass cutter so the smaller pieces are swept inside the cutter wheel and then out through the screw. The rippers do the same thing but a little differently. Either way, these bits and pieces of the boulders should not have been able to damage the seals.

Hitachi is responsible for building a bearing system that doesn't allow debris to cause it to fail. That is why Hitachi Zosen bears some responsibility.

FYI. Each TBM is specially built for the geological conditions specific to the job. While each share similar characteristics to others, most are unique, especially the MEGA-TBMs which STP probably had a hand in designing along with the manufacturer.


Posted Wed, Feb 19, 8 p.m. Inappropriate

4 billion is enough for me to say "pull the plug and build a new viaduct". Doesn't matter that new permits and studies need to happen, this bore tunnel project is a financial disaster and will move so many fewer cars that Seattle businesses will move to Bellevue. Or parts unknown.

Posted Sun, Feb 16, 11:12 p.m. Inappropriate

"from statements made" - I would add 'eventually'. Here is the core concern (pardon the pun): are we in a situation where there's more bad news, and certain decision makers who want this project no matter what know that if the bad news comes out, there will be incredible pressure to cancel the project?

What makes me really suspicious of any claims of what's ahead is first, the way the wall of that well was overlooked, and second, the sense it seems decision makers knew from the time the drill stopped that there was not some mysterious object in the way, but they got everyone trying to think that there was an object.

So, this makes it very hard to be trusting.


Posted Mon, Feb 17, 1:49 p.m. Inappropriate

There is no reason to be trusting. When there is, I'm sure intelligent people will support who/what they trust.

Right now, we have an urgent need for full transparency about potential costs, and a more urgent need for transparency about exactly how the 'experts we do not trust' will be determining whether Bertha can move again.

Trust. Such an urgently necessary word.

Posted Mon, Feb 17, 12:16 p.m. Inappropriate

If they dig a 80'x80' hole, how much does the contractor pay to rent that space from the city or the private landowner? If it shuts down a street, the costs of transportation impacts must be calculated and paid by the contractor. Unless they have a privatize the profit, socialize the losses bid, nice work if you can get it.

Posted Mon, Feb 17, 4 p.m. Inappropriate

The existing dig-to-Bertha operation appears to be confined to the grounds connected with Terminal 46, which is also in use for shipping dirt dug out of the tunnel.

So I guess there might be costs for the Port if tunneling ultimately takes longer than the schedule (which seems likely).

On the other hand, if tunneling is halted early, maybe it would benefit the Port which gets its terminal back and doesn't have to pay its share of deep bore tunnel costs.


Posted Mon, Feb 17, 2:12 p.m. Inappropriate

Is it too early to determine who's getting the shaft here?


Posted Wed, Feb 19, 8:01 p.m. Inappropriate

No, I think we all can feel it now.

Posted Mon, Feb 17, 4:20 p.m. Inappropriate

It’s ironic that the only assurances given to the public are that the viaduct won’t be weakened by excavation measures required for attempts to resuscitate the crippled Bertha, and that “the viaduct is certainly still stable.” Not bad for 63 years old, eh? Even if Bertha chugs to life this afternoon and finishes boring tomorrow, the resulting product would only provide about half the capacity and none of the access of the viaduct. So if and when Bertha ever performs, taxpaying commuters can still look forward to increased congestion downtown for double the cost.

It’s a shame that all of the special interests and their cheerleaders who were responsible for this suboptimized mess didn’t do the obvious and just refurbish or replace the viaduct in the first place. I hope Crosscut will remind us again who they are in future articles instead of just printing daily press releases from the contractors and their PR firms.


Posted Mon, Feb 17, 7:33 p.m. Inappropriate

Yes, I don't think the tunnel was a wise choice. However, many highway tunnels have two bores, or even a third access bore between them. Maybe they should dig two bores and double the capacity, before they park the 90 million dollar tool.

Posted Thu, Feb 20, 11:15 a.m. Inappropriate

Tunnel supporters here are missing the point, or, at least, one of the points. Gov. Gregoire, SDOT, certain City Councilmemebers, and their TV & newspaper ads adopted the mantra, "This is not the Boston Big Dig" and "There will be no trouble boring underground" in addition to "This project is paid for."

Any tunnel supporter who says, "There are always delays and costly overruns with big projects" might want to consider that the above politicians and bureaucrats never acknowledged this while ginning up their facts and drumming up support.


Posted Mon, Feb 24, 7:45 a.m. Inappropriate

This is something new? I'm outraged! A group of politicians actually soft-pedaling the cost of a large project. Oh the humanity!

Jesus F&%$# Christ already. It's a big honkin' project, there will be cost overruns and delays. Five years after the project is up and running this will be old and dried up news.


Posted Tue, Feb 25, 6:23 p.m. Inappropriate

No need to curse Lily32.

Five years from now we will still be bemoaning WSDOT and their incapable work regarding Bertha. By then, the project will be close to $10 Billion spent, and the tunnel still will not be completed. The Viaduct will be drooping another 2 inches, with supports holiding it up since failure of the Viaduct is not an option, now or then.

Think reality.

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