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Tunnel Boring Machine Stopped By Mystery Object (Seattle; 2013)

kamalktk

kamalktk

Antediluvian
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Feb 5, 2011
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Considering tunnel boring machines are designed to grind up anything in their paths, there is naturally speculation as to what could have blocked it.

http://www.seattlepi.com/local/komo...tinues-What-is-blocking-tunneling-5054842.php

The mystery continues: What is blocking tunneling machine under Seattle

The Transportation Department and contractors building a highway tunnel under downtown Seattle are trying to identify the mystery object that has blocked their tunnel boring machine.

The machine called Bertha ran into something Friday and was shut down Saturday about 1,000 feet from the start. The $80 million machine is designed to break up boulders, so there's speculation about what it hit.

Engineers are considering drilling down 60 feet to the object as one of the ways to break up or remove the obstruction. A large crane equipped with a drill bit was seen at the site Wednesday morning.

The nearly two-mile tunnel is supposed to be completed by the end of 2015, creating a four-lane replacement for the Alaskan Way Viaduct on Highway 99.

But already it has experienced at least three delays - one caused by union picketing over work assignments, another by a sinkhole near Jackson Street and now the mystery object.

WSDOT says the latest trouble started Friday when Bertha's five-story tall cutter head felt some resistance, then stopped. WSDOT says engineers with Seattle Tunnel Partners, the company in charge of building the viaduct replacement tunnel, have been consulting with other experts to identify the obstruction - whether it's natural or manmade.

They say Bertha wasn't damaged in any way. They're keeping her idle until they decide whether crews need to dig the obstruction out from above or if Bertha can charge through it.

Bertha has dug 1,000 feet of tunnel since July. She's sitting 60-feet underground between South Jackson Street and South Main Street among a mix of native dirt and fill tossed into place from as early as the 1800s.

She has just 450 more feet to travel before leaving that fill behind. It will also mark the end of phase one in the $4 billion tunnel project that will stretch 1.7 miles from adjacent to Safeco Field to Battery Street.

WSDOT doesn't know how long Bertha will remain stuck, but they say it's too early to say whether the delay will affect the project's bottom line or it's scheduled opening in late 2015.
 
It's either a gigantic diamond or an ancient space vehicle.
 
Spudrick68 said:
Or Quatermass.
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Professor Quatermass? His old flesh and bones wouldn't be hard enough...
 
My money is on the spaceship. Aliens will burst forth and devour every Barista in Seattle.
 
I'm not clear on why they're referring to the obstruction(?) as an 'object'. All they know is that the boring machine encountered resistance. This doesn't necessarily mean it ran up against a single large hard object.

I'm guessing they've run into some unexpectedly hard material among the fill area within which the machine is currently sitting. Seattle's originally hilly terrain has been leveled over the last 100 years with major projects (e.g., the Denny Regrade) around the downtown area. Many buildings were demolished, so it wouldn't be surprising if the mystery material was stone or masonry.
 
Bertha may well have run into something metal. After rummaging through some other news items on the project, I found mention that Bertha cannot cut through steel.

In relation to this ... I ran across multiple references to steel debris, rails, rail cars, and even a dismantled ship having been used as fill in that area at one time or another over the last century and a half.
 
EnolaGaia said:
Bertha may well have run into something metal. After rummaging through some other news items on the project, I found mention that Bertha cannot cut through steel.

In relation to this ... I ran across multiple references to steel debris, rails, rail cars, and even a dismantled ship having been used as fill in that area at one time or another over the last century and a half.
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Yes. I've read about that, too. So, no one mentioned this fact before the project started? You have to wonder.
 
From what I've read - yes, they knew there was a variety of fill materials in Bertha's path. One article I read stated the path of the new tunnel had been probed from surface level in preparation for the work, using both physical drilling-down and some sort of ground-penetrating sensing technique. This probing hadn't hit or indicated anything suggesting such an obstruction.
 
Metal is one of the easiest things to find underground surely?
 
I reckon the object couldn't be detected because it had... moved. :shock:
 
rjmrjmrjm said:
Metal is one of the easiest things to find underground surely?
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Metal is no easier to find than anything else when using physical probes (drilling test holes).

The obstruction is circa 60 feet below the surface. I don't know if that would be within the range of whatever remote sensing technique they supposedly used.
 
I've read enough of Lovecraft to know where this is going...
 
BORING.

Huge tunnel borer Bertha stopped by simple steel pipe in Seattle

The great Seattle mystery has been solved: The object blocking the world’s largest tunnel boring machine isn’t an old steamship or locomotive or alien spaceship – it’s an 8-inch-diameter steel pipe.

The Washington State Department of Transportation said Friday that the steel pipe that stopped Bertha, as the borer is nicknamed, on Dec. 6 is a 119-foot-long well casing installed in 2002 to study groundwater movement under downtown Seattle.

“We need to investigate further to see if there are other factors that could have contributed to the blockage,” Matt Preedy, a deputy administrator on the project, said in a statement.

When it got stuck, big Bertha was only about 1,000 feet into a two-mile-long boring journey under Seattle for the tunnel that will replace the city’s waterfront viaduct – a necessity after damage from a 2001 earthquake. The borer is 60 feet below the surface in an area that actually was above ground when the city was founded but got buried in waves of industrial growth and redevelopment.

The mystery had intrigued Seattleites, with some speculating that an old locomotive or steamship boiler might have been buried in the fill.

"It could be Jimmy Hoffa, it might be Sasquatch or it could be a flying saucer, you know," local historian Feliks Banel told NBC News last month, more than a little tongue in cheek.

That the real culprit is something as mundane as a steel pipe buried only in the past decade might disappoint some, but not the Transportation Department.

“Our focus right now is on resuming tunneling as quickly and safely as possible,” Preedy said.
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http://usnews.nbcnews.com/_news/201...ertha-stopped-by-simple-steel-pipe-in-seattle
 
It's the Time Capsule that the Church of the Flying Spaghetti Monster buried!

Nah, it's a piece of pipe.

I lived in Seattle for a while, and found it to be the hokiest place I ever saw.

Sure is pretty, though.
 
It now appears the machine's stoppage wasn't the result of an obstruction at all ...

Feb 7 update: Two factors contributed to tunnel stoppage

Posted on Feb 7 2014 12:06 PM

For two months, the contractor on the SR 99 Tunnel Project, Seattle Tunnel Partners (STP), has been working to determine what caused the stoppage of the SR 99 tunneling machine on Dec. 6, 2013. WSDOT and STP have identified two contributing factors: a clogged cutterhead and high-temperature readings indicating there were other factors to explore.

A clogged cutterhead

Tunnel workers performed 158 hours of hyperbaric inspections between Jan. 17 and Jan. 28. They found that many of the cutterhead openings were clogged with dirt and other material. A clogged cutterhead can affect the tunneling machine’s performance in the same way that a major obstruction would affect its performance. Once the hyperbaric work was completed, it was determined that a major obstruction was not the cause of the mining difficulty. The more likely cause was the clogged cutterhead.

During the 12 days of hyperbaric work:

Tunnel workers removed the clogs (view video on YouTube) from the cutterhead openings.

No major obstructions were found inside or in front of the machine.
Several cutting tools were replaced (view video on YouTube).

STP and WSDOT will continue to review the data and information gathered from the hyperbaric inspections.

High-temperature readings

After the cutterhead was unclogged, the contractor moved the machine forward an additional 2 feet and installed one of the concrete rings that line the tunnel. On Jan. 28 and 29, higher-than-normal heat sensor readings appeared like they did on Dec. 6, 2013. In the course of investigating the temperature readings, STP discovered damage to the seal system that protects the tunneling machine’s main bearing.

The main bearing is what allows the cutterhead to spin. It is similar to the bearing on the axle of a car, which is protected by a seal that keeps lubrication in and road grime out. The tunneling machine’s main bearing is protected by seals that function the same way - they keep the bearing lubrication in and the tunnel muck out. Investigations have shown that portions of the seal system have been damaged and need to be repaired or replaced. STP and its tunneling experts are working with the machine’s manufacturer to determine the best fix for this issue. They are currently assessing the extent of the damage and the best path forward.

Cost and Schedule

STP is the design-build contractor of this project, which requires cutting-edge engineering and design practices. The tunneling machine is owned by STP. It is STP’s responsibility to determine the scope of the issue and the best options to repair it and get the machine moving again. WSDOT expects to receive specific information on the impact to the project schedule and costs once STP determines a solution to the current situation. WSDOT oversees this mega-project and has both independent experts and onsite tunneling inspectors providing continuous analysis and review. We all share the same goal - to build the tunnel and remove the Alaskan Way Viaduct in a timely manner.

SOURCE: http://www.wsdot.wa.gov/Projects/Viaduc ... splay/1457
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Clogged up with coffee mugs, shorn hair from goatees, and black clothing, I'll wager.
 
I like the Viaduct-it's a place to get out of the rain.
 
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