View Full Version : OT: simple repair of bearing and seal

12-10-2014, 10:20 AM
So, your tunnel boring machine is stuck underground in Seattle, Washington with a blown main bearing and seal: whacha gonna do?

NYTimes article:

Brief pictorial overview of repair:

Detailed Repair plan (41 pages, takes some time to load)

12-10-2014, 11:28 AM
So, your tunnel boring machine is stuck underground in Seattle, Washington with a blown main bearing and seal: whacha gonna do?

Bill the city for all repair costs plus reasonable rate of return on capital and working costs!

12-10-2014, 11:35 AM
It was still under warranty (just...) when it died. Luckily it stopped when you COULD dig a vertical access shaft. If it was under the freeway or buildings (most of its dig), we'd still be scratching heads.

The vertical access shaft dig required extensive de-watering of the area; nearby buildings and the freeway have sunk 1 inch in a month. Expect more delays while this is "studied".

If we have an earthquake....lol...

12-10-2014, 01:50 PM

You forgot to mention the Viaduct above it and the Seawall just a bit beside it. They have already spent 1 billion of the 1.44 billion of their budget. We don't even want to mention that WASDOT does not have even a hint of what to do if the "repair" does not work. At least when the Viaduct falls down there will be better views of Puget Sound.

03-25-2015, 10:50 AM
Updates on repair of TBM "Bertha"

Feb/early March 2015:

TBM bores through the access pit wall:

TBM moves into the access pit:

TBM Component lifts through the access pit, beginning March 18, 2015:

1'st lift:

2'nd lift (no pix?)

3'rd lift:

4'th lift (yet to come: cutter head and main drive assembly)

Some overview/coverage of TBM repair:

Detailed repair discussion and animations:

And a precious viewers comment from the previous:

"We begin by tying a string to Bertha's tooth. The other end is then tied to the knob of a door. When the time is right we will then slam the door shut extracting the bad tooth. Upon completion of the removal of said tooth we will then place it under Bertha's pillow. Hopefully by morning the tooth fairy will pay a visit and leave $195,000,000.00 to help pay for the procedure."

General project page:


03-25-2015, 11:29 PM
Interesting they are using a Japanese machine when the Robbins Co, maker of TBMs, is in Kent WA.

03-26-2015, 08:32 AM
So guess they tried some lucas oil additive to see if that would quiet the bearing down before going threw the work of changing it?

03-26-2015, 10:04 PM
STP for the old timers.

03-27-2015, 08:10 AM
Richard Petty would say so.

03-27-2015, 09:02 AM
Building 'Bertha'

Engineer #1: So what happens if the main bearing goes out while it is underground?
Engineer #2: You dig it up and fix it.
Engineer #1: But what if you can't because it is under a 40 story building or under a bay.
Engineer #3: You don't want to think about that.
Engineer #2: Yeah, you don't want to think about that.

Am I the only one wondering why you wouldn't have rear access to sorta important parts like main bearings? Is this common?

Edit: Maybe I'm jumping here and this was easier than rear removal.

03-27-2015, 12:07 PM
The machine is ahead of the concrete that forms the tunnel - you can't back up the machine or get to the bearing or front from the rear. It has to seal the hydrostatic pressure ahead also.

This machine is huge - the largest in the world. A couple of slightly smaller machine also boring tunnels in Seattle are doing fine; one just finished its tunnel and the other will be done in week or two.

03-27-2015, 12:43 PM
Wow, so if it fails then you have no choice but to dig it out to fix it.

03-27-2015, 12:50 PM
Turns out TBM Bertha isn't the first of her kind to need a subsurface main bearing replacement. In 1993, TBM 'Excalibore' went kerput on the job at Sarnia, Ontario, on a bore under the St. Clair river:


The above is a detailed, lengthy history of railroading between Michigan and Ontario via the St. Clair river (surface and subsurface). It's worth a read if you've got the time.

03-27-2015, 01:04 PM
Wow, so if it fails then you have no choice but to dig it out to fix it.

Or... bury in place, and make a new tunnel. There are many place under Seattle where it wouldn't be possible to access it. Luckily it failed early in the dig.

03-28-2015, 01:26 AM
Btw..... the cutter head alone is 2000 tons... They figure 16 hours to lift it up the 120 foot access shaft and place on the ground. Should happen real soon.

03-28-2015, 07:36 AM
Lucky they had access. I'm certainly not an engineer nor a tunneling machine maker but what a risk to not have rear access. I get the part about having 2 different radius with the concrete getting formed behind, but still, there is no other way?
From wiki it would appear this is the machines first tunnel. 800' and its broken?

03-28-2015, 08:39 AM
I wonder if there was casting material left in the bearing from manufacturing. Don't they know you are supposed to dismantle, clean, and put in good new lube in any import machines. Jeez that has been covered how many times here?

04-02-2015, 08:26 PM
Video of Bertha's front-end being lifted to the surface: 2000 (not 200) tons of cutter-head, main bearing & seal, support structure and drive assembly. The lift was done Monday evening, March 30:


Current (updating) views of the TBM front end in its parking cradle: see clickable images entitled "access pit #1" and "access pit #2", (upper right image, and lefthand image one row down) in the image array:


Views #1 and #2 are on opposite sides of the lifting crane. In the foreground of view #1 can be seen a second parking cradle. Apparently that will be used to reassemble the front end using new parts shipped from Japan (*) and used parts removed from the old front-end on the first parking cradle.

* Notably including a new bearing and seal

12-image photo coverage of the front-end lift:

Some technical detail on the TBM can be found here:


04-03-2015, 08:40 AM
The scale of that machine is mind bending.
I still think it is not a good idea to not have the thing serviceable from the rear.
Suppose it gets 1/2 way there and is under water, what then?
Build another one and drill from the other side and then cut them both up for scrap?

04-03-2015, 09:09 AM
Video of Bertha's front-end being lifted to the surface: 200 tons of cutter-head, main bearing & seal, support structure and drive assembly. The lift was done Monday evening, March 30:


haha, I like the guy in the white shirt (like many of them it seems) that wasted the entire day away leaning on the fence and crane jack.

04-03-2015, 01:33 PM
The local guys report the cutter head as 2000 tons, not 200. One of them is right :)

I'd like to get the old bearing, but I doubt my Lille pickup would carry it. lol

04-03-2015, 02:31 PM
The local guys report the cutter had as 2000 tons, not 200. One of them is right :)

I'd like to get the old bearing, but I doubt my Lille pickup would carry it. lol

200 versus 2000 tons:

I've seen both figures used, as well as a stipulated 240-ton limit for the lifting crane. Ergo, I went with the smaller figure. The situation is muddied by the fact that the cutting head (and attached 'stuff') is actually the last of four individual pieces of the TBM front end that were lifted separately. Do those four parts add up to 2000 tons?

04-03-2015, 02:46 PM
The Mammoet folks say a single 2200 ton lift for the "front end":


And Engineering News Record specifies a 2425 ton load-limit for the Mammoet modular lift tower crane that raised Bertha's "front end":


04-03-2015, 08:22 PM
If it's a 2000 ton cutter head it's a hell of a big tunnel!
I somehow think neither figure is right, I'm guessing more than 200 and less than 2000, I've seen a crane lifting 1500 tons close up and personal and it was amazing, mammoet have a 3600 ton beast, that's ginormous, whatever it is it's quite a feat lifting the end off a TBM anyway, very slick but as has been said very expensive, they've come on a lot since the original tunnel shield.
I suppose these TBMs will only get bigger.

04-03-2015, 08:27 PM
It is a big tunnel... 57 feet diameter bore, and this is the world's largest TBM

The cutter head alone is head is 4 million lbs (sounds so much bigger than 2000 tons!).



04-03-2015, 08:35 PM
Bloody hell that's a motorway over here!

04-03-2015, 09:17 PM
Here's a good image of the cutter-head assembly hovering over the parking cradle. Two kilo-tons, eh?


04-03-2015, 11:31 PM
I found it on page 1,847 of the McMaster/Carr catalog.

Item # 24z235680

"Main bearing and seal for 2,000 Ton TBM"

call for pricing

04-03-2015, 11:39 PM
Bloody hell that's a motorway over here!

It's for a double deck motorway here!

04-06-2015, 01:27 AM
What I love is the road it is supposed to be replacing is four lanes each direction. Last time I drove it, ten years ago it would pile up with traffic two three times a day.

The tunnel to "replace" it is three lanes one way, two the other.

What could go wrong? :)


10-08-2015, 02:23 PM
An Oct 7 update with video of repair progress on Big Bertha:


10-08-2015, 05:22 PM
wow, that's seriously non-trivial stuff! I loved that clip of the external trimming of the center section - I wonder how big those chips were?

10-08-2015, 05:42 PM
I should imagine they are big enough to brand you with the " mark of the beast" as one mill operator I knew called it, it was a 6 btw, quite funny at the time as it was on his arse, not behind his ear.

10-08-2015, 08:24 PM
$80 million so far to fix...

12-22-2015, 07:32 PM
Big Bertha on the move today (baby steps):


04-19-2016, 08:54 AM
(1) By January 7, Big Bertha had traveled 73 feet since the completion of repairs:


(2) On January 14, tunneling was stopped due to concerns about sinkholes forming above the TBM. Operations resumed February 23:


(3) On March 12, operations were stopped for scheduled TBM maintenance:


It appears that operations have not yet resumed. When they do, the TBM will shortly be under the Alaskan Way Viaduct, forcing its closure for some weeks:


To-date, Bertha has traveled 1,560 of 9,270 feet.

04-19-2016, 11:18 AM
It in good shape... just waiting for the prep work to be completed for the boring beneath the viaduct starting NEXT Friday.. Lots of extra pilings driven, carbon fiber wrap applied on the concrete, and the butterflies in the WDOT engineers stomachs have to settle.. ;)

I work 100 feet from the viaduct. It's going to be glorious (quiet) to have no traffic on it, but a nightmare with traffic getting to work while closed. For those who don't know what I'm taking about, imagine shutting down a major freeway though your city for two weeks. lol

03-16-2017, 06:06 PM
Article devoted to Big Bertha on Popular Mechanics site:


The old gal is 556 feet away from the end ....

03-16-2017, 06:57 PM
Remarkable feat of engineering, difficult on the ground, down the bottom of a hole, amazing.
Just lining up the drive ring gear segments is difficult, we had a slew ring to change on a caster ladle turret some years ago, I've never clocked over 25 feet before, it was difficult and that was horizontal, can't imagine doing it vertical, the gas cage of 12 argon bottles sitting on top of it gave an impression of the scale, huge, they haven't repaired it they have remanufactured it, must have been like fixing a submarine on the bottom of the sea

03-16-2017, 07:45 PM
I like the "heat treating" of the inserts. lol

03-16-2017, 08:43 PM
Remarkable feat of engineering,

Last week it was 10" offline. The Romans were better underground engineers:rolleyes:

04-05-2017, 09:15 AM
Bertha broke through into the disassembly pit yesterday at noon: