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Old May 9th, 2007, 01:01 AM   #621
spongeg
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Crews bore nearly mile-long tunnel for Seattle light rail


Chunks of a concrete support beam fall as a tunnel boring machine, turning a 21-foot diameter cutting head, breaks through a support wall today in Seattle to complete the boring of a 4,388-foot tunnel under Seattle's Beacon Hill neighborhood. The tunnel will be used for a 14-mile Sound Transit light-rail line from downtown Seattle to Seattle-Tacoma International Airport. The line is scheduled to begin operation in late 2009.


SEATTLE -- An enormous drill broke through the east side of Beacon Hill in the city's south end this morning, almost a year after it started digging a nearly mile-long light-rail tunnel.

With a crowd of onlookers intently watching, the Japanese-built tunnel-boring machine, with its 21-foot diameter cutter head, slowly churned into view a little after 8:15 a.m.

Pat Gould, who was driving the 375-ton machine, was the first of several underground crew members to emerge from the freshly dug tunnel -- the first of two being built for a 14-mile Sound Transit line that will stretch from downtown to Seattle-Tacoma International Airport.

"It felt great," Gould told The Associated Press after the cheering and clapping died down. "It's a good day for Sound Transit and Seattle to get this light rail, the first phase of it, complete."

Sound Transit, a mass transportation agency that serves King, Pierce and Snohomish counties, runs express buses, a commuter train, park-and-ride lots and a light-rail line in Tacoma. Project leaders say the light-rail line from Seattle to the airport is on schedule to open in late 2009.

Nearly a football field in length, the tunnel-boring machine is equipped with a laser guidance system that dug the 4,388-foot-long hole within 5 millimeters of engineers' plans, Gould said.

Manufactured by Japan's Mitsubishi Heavy Industries, it made about 50 feet of progress per day on average -- 60 feet "once we really got going, and once the crews got comfortable with the operation," he said.

Next up: Sound Transit crews will finish laying the concrete rings that line the tunnel, then take the machine apart, move it back to the west side of Beacon Hill, reassemble it, test it, then start digging the second, parallel tunnel.

http://blog.oregonlive.com/breakingn...elong_tun.html
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Old May 9th, 2007, 01:26 AM   #622
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50 feet per day!--60 even!

And tunneling is expensive?

I swear its a propaganda campaign that tunneling is "just too expensive"! To go one mile, that's about 3.5 months--sounds fast to me!

Time is money, baby.

Nate
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Old May 9th, 2007, 04:05 AM   #623
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WOW! I'm glad it is getting there!

One thing I am confused with last part of this article...

"...then start digging the second, parallel tunnel."

Does it means it will have a second tunnel under Beacon Hill neighborhood? Or its mean it will start digging under Capital Hill neighborhood?
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Old May 9th, 2007, 04:20 AM   #624
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WOW! I'm glad it is getting there!

One thing I am confused with last part of this article...

"...then start digging the second, parallel tunnel."

Does it means it will have a second tunnel under Beacon Hill neighborhood? Or its mean it will start digging under Capital Hill neighborhood?
From the digging rig config., I think you need two tunnels one heading in and one heading out of the city.
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Old May 9th, 2007, 04:25 AM   #625
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Ohhh I thought one tunnel would fit both tracks in different directions? I guess that tunnel is not big enough to fit two separate tracks.
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Old May 9th, 2007, 05:07 AM   #626
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Ohhh I thought one tunnel would fit both tracks in different directions? I guess that tunnel is not big enough to fit two separate tracks.
In the article with the pic., it reports that the diameter of the machine is only 21 feet. You need to deduct about 2 feet from that figure to accommodate supportive linnings. That leave you with about 19 feet at the widest. Which by the way is not the middle since you need to elevate the bottom to gain enough room to set rails.
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Old May 9th, 2007, 05:25 AM   #627
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Oh okay. Thanks for the explaination.
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Old May 9th, 2007, 05:38 AM   #628
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There are other options like this one.



but the cost for lease is probably more than double the single tube type.
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Old May 9th, 2007, 05:40 AM   #629
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That interesting machine... I never seen something like this before... I am sure it costs double than single one for sure!
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Old May 9th, 2007, 09:43 AM   #630
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The two tunnels aren't perfectly aligned so as to make use of a machine like the one above. Bummer eh? That'd save some time, as elaborated on below:

The tunnel length is 4300 feet. That means at 50-60 feet per day for the entire tunnel, it'll take 71-86 days to dig, that's 10-12 weeks. However, the tunneling started in January. I don't know specifically what week, but that would make it between 14 and 18 weeks from when it started. There's a lot of issues that require stopping be it planned or otherwise, such as travel through the station excavation or the accidental death of a worker.

Given the actual time frame in weeks, we're looking at 98-126 days to bore 4300 feet, or 34-43 feet per day. If the same schedule holds true, and the start of the second tunnel does begin in June, then we'll see the second breakthrough in September, maybe the beginning of October.

Why I just bothered with all this multiplying and dividing, I don't know, but it's here anyway.
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Old May 9th, 2007, 09:51 AM   #631
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True...

Supposely when they start digging under Capital Hill neighborhood... Three miles tunnel... How long do you think it will takes to reach to University District from Westlake Center station?
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Old May 9th, 2007, 10:39 AM   #632
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Nice to see light at the end of the tunnel!
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Old May 9th, 2007, 05:49 PM   #633
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Quote:
Originally Posted by Jaxom92 View Post
The two tunnels aren't perfectly aligned so as to make use of a machine like the one above. Bummer eh? That'd save some time, as elaborated on below:

The tunnel length is 4300 feet. That means at 50-60 feet per day for the entire tunnel, it'll take 71-86 days to dig, that's 10-12 weeks. However, the tunneling started in January. I don't know specifically what week, but that would make it between 14 and 18 weeks from when it started. There's a lot of issues that require stopping be it planned or otherwise, such as travel through the station excavation or the accidental death of a worker.

Given the actual time frame in weeks, we're looking at 98-126 days to bore 4300 feet, or 34-43 feet per day. If the same schedule holds true, and the start of the second tunnel does begin in June, then we'll see the second breakthrough in September, maybe the beginning of October.

Why I just bothered with all this multiplying and dividing, I don't know, but it's here anyway.

Sure, I wouldn't include stations in that calculation I made. I really think underground stations are what make tunneling expense more than anything else. But, I did get the impression they were indeed averaging 50 ft per day, which would include incidental compliations. I wonder if the type of rock is the key determinant in boring speed here.

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Old May 9th, 2007, 07:16 PM   #634
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Quote:
Originally Posted by getontrac View Post
Sure, I wouldn't include stations in that calculation I made. I really think underground stations are what make tunneling expense more than anything else. But, I did get the impression they were indeed averaging 50 ft per day, which would include incidental compliations. I wonder if the type of rock is the key determinant in boring speed here.

Nate
Stations are built after the burrowing is finished.
Although it takes time for these machines to burrow through a layer of granite it is not the most difficult since a layer of granite has little risk of a caving in. The down side is you need to replace the bits when burrowing through granites since they wore out easily. I do not know if the machine that is actually used for this construction is equiped but there are machines that you can change the bits without stopping for maintance.
On the other hand, the most danerous type of soil to burrow through is mud trenched with water.
The shield machine has three functions, pressurization of contact area to keep water from gushing in, actual burrowing and placing supportive lining into burrowed area.
This is the main reason Japan relies heavily on this machine since most of the tunnels burrowed beneath Tokyo is mud.
Although these machines cost hell of alot to lease it is well worth it if you consider the risk of accidental flash blasts, cave ins, flooding, and other potential hazards related to tunneling.
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Old May 9th, 2007, 10:22 PM   #635
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http://www.soundtransit.org/x5788.xml The video of the boring machine popping out of the light.
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Old May 10th, 2007, 12:00 AM   #636
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Quote:
Originally Posted by getontrac View Post
Sure, I wouldn't include stations in that calculation I made. I really think underground stations are what make tunneling expense more than anything else. But, I did get the impression they were indeed averaging 50 ft per day, which would include incidental compliations. I wonder if the type of rock is the key determinant in boring speed here.

Nate
So 50 feet per day if we take out downtimes. That sounds reasonable.

Thanks for linking to that video sequoias!
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Old May 12th, 2007, 11:12 PM   #637
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Quote:
Originally Posted by Jaxom92 View Post
So 50 feet per day if we take out downtimes. That sounds reasonable.

Thanks for linking to that video sequoias!
No problem!
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Old May 17th, 2007, 07:39 PM   #638
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Tuesday there was an update the the ballot measure for the Roads and Transit package. The change was to simplify the vote so it is clear to voters what they're voting on and why both roads and transit must be voted together.

The jist is that before this legislation, the vote would have been two seperate yes or no answers, one for transit, one for roads. If either one recieved a no majority, then both would not be passed, even if the other received a yes majority. Now the vote has been merged into one question.

You can view the whole news release here.
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Old May 22nd, 2007, 12:17 AM   #639
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There was an article in the Seattle Times this morning about the south lake union street car. (Get it here.) While it's not directly related to the light rail, there has been discussion in this thread about the streetcar. The article brings up some good points of concern about the line.

Of particular interest to me is the fact that the line will not be in it's own R.O.W. This has the potential to make, as the article said, walking just as quick and less expensive than taking the car. With Seattle weather, perhaps it might be better off, and you're not having to huff it however many blocks. Still, it does slow down the speed at which the car can travel and get stuck in the same traffic. I'm extremely disappointed that it was developed this way.

Incidentally, the statement about Tacoma's link being traffic separated is only half true. On busy Pacific avenue, the line is in the median, however once it starts running on commerce street, the traffic lanes are shared in certain places, causing delays. I've personally been on the train when there was a "snarl" between inattentive motorists and the train. Nothing serious, but the train was unable to move until the traffic cleared out.

To me, shared right of way is the worst thing to do when you're trying to maximize the competitiveness of transit versus other forms of transportation, namely the car.
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Old May 22nd, 2007, 10:16 PM   #640
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On tunneling under Beacon Hill

They have not come close to averaging 50ft/day - in fact, I suspect they averaged more like 10-15ft/day. They're not digging through rock - Seattle's hills are unstable glacial till - mostly clay.

The station platforms are center - between the two tunnels. Using a double borer as shown in an earlier post would have necessitated a different and much more expensive Beacon Hill station design - as it is, they have a primary and ancillary shaft sunk between the two tunnels, making the amount of work having to be done underground (and this station is 165-180 feet down) minimal.
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