Bertha may be on hold until summer for complicated repairs

The Seattle Times ^ | 2/10/2014 | Mike Lindblom

[steve86]

Seattle Tunnel Partners says it might repair Bertha’s damaged seals from the front end, which would require a digging deep hole along the waterfront and could delay the Highway 99 replacement project for months.

Workers might have to dig a hole up to 115 feet deep to reach and repair the damaged drive system of tunnel-boring machine Bertha, contractors now say.

Once the pit was dug, the 630-ton cutter head would be detached and lifted using a crane, supported by wide footings as if on duck feet, so it wouldn’t sink into the soft waterfront soils.

Chris Dixon, director for Seattle Tunnel Partners (STP), said Monday his team is weighing “four or five options” for a front-end mission, and coordinating the use of waterfront surface space with the city’s nearby Elliott Bay Seawall project.

[...]

The $80 million tunnel machine has damage to the seals that lubricate and protect the $5 million main bearing. This bearing enables the ring-shaped drive shaft to turn the cutter, at about one rotation per minute.

Sand was found in the seal grease, and high temperatures have occurred in the main bearing, according to WSDOT interviews and quality-inspection records.

[steve86]

The seal and bearing have about a 25-foot diameter, impossible to deliver through the rear unless either the parts or the tunnel machine are disassembled.

[dr_lew]

Seems like an open ended problem. $5 million ... $80 million ... what will these delays and repairs cost ?

[upchuck]

Thanks for posting this. I was wondering how Bertha was getting along. Poor girl, doesn’t sound good.

[Ray76]

Can the machine be backed out of the tunnel?

[steve86]

I think it will back up about 18 inches on its own. For more than that you have to remove all the concrete liners in the tunnel that have been installed behind it. And even then you’d be dragging it out, ruining it.

[Defiant]

Did they figure out what they hit that couldn’t be drilled? My money is on a new element, Hillarium.

[skinkinthegrass]

don't know, many others machine like this are
left/parked in a side tunnel off the main one
after final construction.

[steve86]

Naked Bertha Photos:

https://www.google.com/search?q=bertha+tunnel&num=20&hs=REo&rls=org.mozilla:en-US:official&source=lnms&tbm=isch&sa=X&ei=R8n5Upq8J-jcyQGYkYDYAQ&ved=0CAwQ_AUoBA&biw=1442&bih=888

[Ray76]

>> many others machine like this are left/parked in a side tunnel

That’s true.

[Ray76]

Well then, tunnel boring machines could use a design review.

[entropy12]

Dump Bertha and hire illegals. They are experts in tunneling.

[pepsionice]

All those poor union guys who operate it....I guess they get paid while idle?

[GeronL]

bump

another boondoggle

[gunsequalfreedom]

Thanks for posting this. I was wondering how Bertha was getting along. Poor girl, doesn’t sound good.

I too was wondering.

So it turns out it was not a rock or an old car but sand that caused the machine to stop?

[rawhide]

Seattle's Big Dig boondoggle.

[gunsequalfreedom]

I said it was sand that caused it to stop when it first came to a halt. (heading back to dig up that post of mine).

When you're good you're good.

[GeronL]

Do they have surfing on the Oregon coast? Bertha has a vacation going on!

[21twelve]

The seals are bad that protect the main bearing. But the machine was running hot from the very beginning - so perhaps an installation or design problem. Of course drilling through the drill pipe may have furthered the problem and damaged the seal even more?

And even when/if they get the thing fixed, they still have most of the tunnel left to dig.

[Lockbox]

Can the machine be backed out of the tunnel?

No, they put the tunnel lining up as the machine drills. The lining is smaller then Big Bertha.

[Right Wing Assault]

Did they figure out what they hit that couldn’t be drilled?

It hit a steel pipe.

http://www.equipmentworld.com/a-steel-pipe-is-what-brought-bertha-the-worlds-largest-tunnel-boring-machine-to-a-halt/