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800 Maynard Ave S, Suite 200, Seattle, WA 98134
800 Maynard Ave S, Suite 200, Seattle, WA 98134
Sounds suspiciously like the line Gregoire's, cum Inslee's, mega-projects people gave on the Columbia River Crossing boondoggle. "Vancouver [WA] won't get light rail unless we build this monstrosity."
Meanwhile U-Link is early and under budget. But nice try, Ed.
So when Ed Murray says the following, he could just as well be speaking for me: "My fear around Bertha isn’t so much isn’t that the current tunnel can’t be built. But I believe [its failure] will kill any opportunity to build a fourth tunnel through Seattle. The ultimate answer to transit through downtown Seattle is for light rail to come through downtown Seattle from West Seattle or Ballard.”
When it comes to the deep-bore tunnel, that really is my dog in the fight. I hope it succeeds if for no other reason than I fear that its failure will create some insurmountable resistance to building a second downtown transit tunnel.
I hope my fear is unfounded. I realize these are two vastly different tunnel projects, and that a second downtown transit tunnel would be nowhere near the engineering big deal that the DBT is. I realize the two projects really should be unrelated. I realize I'm talking not so much about engineering as political and public perception.
I tend to take Murray at face value on this and not see some sinister motive. In this respect, I'm really relieved to be hearing such a statement from him. I voted for Mike McGinn because I've regarded him as more sincerely pro-transit, but if Murray proves to be more effective in actually getting transit built--well, I'll take results over righteous any day.
It's pretty common in light rail networks to have some overlap, and it would avoid tearing up more of downtown. Plus the downtown stations are huge and can easily handle more rail traffic.
I was joking.
It's bitter irony.
Many of the same people who are saying how much we need to go from West Seattle to Ballard were using that very same criticism -- "No one wants yo go from West Seattle to Ballard!" -- during the monorail failure.
How quickly people change their spots when convenient.
Adding a Ballard-West Seattle line into the mix would put the tunnel right around that 30 trains an hour. It also makes a complete mess of interlining headways. Because of all of that any planning for a Ballard - Downtown - West Seattle line has it either terminate on the edges of downtown, or include a second tunnel.
Perfectly good train tunnels are far smaller and we've proven we can build them.
Stick a fork in Ed Murray, he's grasping for straw men.
Was it robotslave who reminded us recently that Hitachi Zosen was way out on a limb with their design for the Bertha tunneling machine (much bigger than previous models; awkward and untested compromise among parameters for different soil conditions)?
Anybody wanting to propose a more rational tunnel (specific to mass transit needs rather than auto/truck traffic; smaller and routed anywhere other than the notoriously unstable and unpredictable reclaimed-land zone of the downtown waterfront) should take pains to distance themselves from the Bertha flustercuck and STP/Hitachi Zosen.
@BerthaDeBlues
We tried Ed Murray wishful thinking & magic realism of zero problem tunnel solutions- they don't work
With that said, we do need rapid transit between downtown and West Seattle/Ballard, but the two can ideas can co-exist (cross bay ferry service and rapid transit to/from downton)
"Mayor takes over Seattle Schools"
The Mayor, in his short time as mayor, has taken over Parks, will create a new system of pre-K (that will compete with the fed program and the state program at a much higher than advertised cost) AND is still trying to get a tunnel built.
Adding the takeover of Seattle Schools (which would need legislative approval) seems a huge stretch of both ability and bandwidth.
(Note: even though this is the Times' stated wish, Murray is also contemplating it but continues to deny he is. Just wait.)
Here's what happened - the drill broke. Everyone who predicted that has some credibility. Everyone else just said "something bad might happen..." And now wants to tell us how right they were and how we should listen to their next prediction.
Murray's point seems to be that purse string holders in Olympia are only as smart as "tunnel broken mean all tunnel bad." And so if Bertha is left to rot, we'll have to deal with all those idiots as a road block to getting transit done, much like the ones here who want "I told you so" credit for predicting that some nonspecific bad thing might happen at some non specific time in the future.
So now I guess I'm back to my view of Ed Murray as the "wolf in sheep's clothes" of pro-transit politicians.
That said, I'm still pleasantly taken aback at his coming out and saying, "The ultimate answer to transit through downtown Seattle is for light rail to come through downtown Seattle from West Seattle or Ballard." Hence, my initial reaction. Maybe the Seattle Subway folks have the mayor's ear.
And having given my "on the other hand" to my original comment, I could lay out another "on the other hand" to this one--that basically things aren't as simple as I'm making them out to be.
+1 on @18 and @21 on how a new transit tunnel is nothing like the deep-bore tunnel.
Folks, contact your state legislators and tell them to get behind this. And I'd love to hear Sydney Brownstone here ask the mayor a follow-up question, "Would you support Rep. Farrell's ST3 bill?"
Bertha has no reverse gear so there’s no way to back it out. What I don't understand is: didn't Seattle Tunnel Partners consider the possibility that the machine might encounter a problem while digging and would need to be repaired? It sure seems like something you'd want to be prepared for.
the machine has a larger diameter than the concrete-lined tunnel it poops out of its rear end
OK, so that's why no reverse; it simply can't be backed up given the existing tunnel-lining process. Could that tunnel-lining process have been modified in some way in order to allow the machine to be backed up if necessary? I would think so but it undoubtedly would have cost more money and, again, I'd bet that STP decided that the chance that Bertha would need to be repaired was so remote that it wasn't worth that cost. They stuck with a plan where, if something happened to the machine, the only option is to do what they're doing -- or trying to do now -- dig down into it. And considering that no forward tunneling progress has been made for over a year, and they still have not reached the machine to haul parts out to repair it, that doesn't seem like a very wise plan.
Not yet.
The engineering problem here is that for the length of the boring machine, the only thing keeping the pre-lined tunnel from caving in is the machine itself.
If the lined tunnel were going to be big enough for the machine to back out, the pre-lined tunnel would have to be bigger than the machine-- and the machine would no longer be preventing that pre-lined tunnel from collapsing. This tunnel-holding-up aspect of the design is referred to as the "tunnel shield," and tunnel shields have been in use in one form or another for about 100 years longer than the modern combination boring+lining machines.
Modern tunneling machines have been evolving for some 50 years now. f you've got a sound idea of how to build a combination boring head + shield + lining machine that can back out of its own lined, structurally stable hole, there are several enormous multinational civil engineering firms that would love to hear from you.
Trust me, you're not the first person to think that it might be good to be able to put one of these mole-mobiles in reverse.
Oh, also: there are and were plans to repair the machine in-place (without digging a pit down from the surface in front of it) if needed. But it's faster, cheaper, and safer to do it the way they're currently going about it, when conditions allow.
Just trying to explain why you can't build a simple reverse gear into one of these things.
I don't know the exact details of what's going on, but part of the function of the bore-head is to hold back the weight of all of the backfilled earth that's in front of it, and that threatens to collapse into the tunnel it's dug if they pull it back. This collapsing earth must by necessity come from SOMEWHERE, and in this case that somewhere is under the foundations of buildings in Pioneer Square. If you think the settling we've seen so far is bad, you'd hate to see the result of removing the TBM. Incidentally, I think this is why the TBM can't be easily repaired where it is. The broken bit in question seems to play a part in holding the earthen wall in front of it up.
Side note: The technique was actually invented in the 1820s for a tunnel under the Thames river by Marc Brunel, (father of Isambard Kingdom Brunel, who did basically every cool civil engineering thing that could be done in early 19th century Britain.) http://en.wikipedia.org/wiki/Tunnelling_…
Second, he may be worried that Bertha failing will somehow get everyone scared about tunnels. That is ridiculous. Transit tunnels are being built right now, and they have all been hugely successful (they are being completed way earlier than expected). Furthermore, it is a different company and a different tunnel. The company that is building the 99 tunnel has a bad reputation. The company that is building (or has built) the transit tunnels has a great reputation. But mainly a downtown transit tunnel on fourth has none of the engineering challenges that the 99 tunnel has. That is a ridiculous comparison.
45: this is not meant to be any sort of endorsement of the colossally stupid design they went with for this project, nor of the choice of a relatively inexperienced firm to build the machine, nor of the decision to replace the viaduct with a tunnel to begin with.
Thanks, and I didn't take it that way.
you can also visit http://www.ride.com/ for more information.
Please someone talk me down from this idea, because I don't have an engineering background whatsoever, but it seems pretty simple.
We all know those types, right? The ones who just shit on every last little thing that doesn't go exactly as they think it should have gone and don't understand anything about long term planning. The fuck you, got mines. Those are the folks that I believe the Mayor is worried about.
While it's perfectly true that the transit tunnels being done by Sound Transit, those aren't getting the attention that the Bertha issue is.
Your first sentence is not true. The numbers you were looking at were with the buses removed. I agree with everything else you said, but removing the buses from the DTTT wont fix the headway problem if you add a whole new line.
That all makes sense. Thank you sir/madame!
I love the juxtaposition of your comment and your username
Even in a non-EPB design, if you were to contract the shield, then there would be nothing holding the unlined tunnel occupied by the machine in place, and it would in all likelihood collapse. The collapse would then crush your contracted shield (and destroy your machine, and drop whatever is sitting on the surface above by some fraction of your machine diameter, and fill at least some your completed lined hole with debris) because when you've got the shield sectioned and contracted like a cylindrical leaf shutter, it no longer has any of the structural strength of a circle.
Again, the large teams of engineers who design and build these things aren't anywhere near as stupid as the peanut gallery seems to think they are, and if you've got a viable way to extract a tunneling machine through its own lined hole for repairs, there are several enormous international civil engineering firms that would love to hear from you.
Just so we don't get more questions like this, let me reiterate:
The machine itself is preventing the hole from collapsing, and the hole will collapse if you take out the machine.
@60 In our particular case, to suggest that Bertha is pressurizing the tunnel is getting things backwards. Bertha is well below the water table, and the ambient pressure is about what it would be at the same depth below water (you'd reach 4 atmospheres about 100 feet down). It would be somewhat less misleading to say that Bertha is depressurizing the cabin (like a submarine) rather than pressurizing the cutting face.
Some of us have seen this show already; The Boston big dig which went from 2.8 Billion to 22 billion dollars. Look it up. Things we haven't seen here yet are; cost of rat mitigation. When you dig a tunnel through a densely inhabited waterfront, the local wildlife decides to move a few blocks uptown. I'm still expecting the Mexico City/Rome discovery of the ruins of a Native American village at tunnel level.
Oh, and the brave statements that Seattle taxpayers won't have to pay for the cost overruns. Stay tuned when Murray and the City Council announce that they're really surprised to find we do have to pay for it.
It's possible to build a transit tunnel with less stupidity than the Viaduct replacement. However you still have the same expert management. Why would anyone vote for a repeat of that?
I spend my time advocating for transit, so I'm not going to worry too much about the Bertha tunnel. As someone who is not involved in the project, I cant fix it.
As for your last point "It's possible to build a transit tunnel with less stupidity than the Viaduct replacement. However you still have the same expert management. Why would anyone vote for a repeat of that?"
The management is not the same. Link tunnels are being built by different contractors completely, and the contracts are being overseen by Sound Transit, not the Washington State Dept. of Transportation(WSDOT). Sound Transit has been very effective at delivering their projects. The U-Link extension is right now 8+ months ahead of schedule, and $200M under budget. WSDOT's problems with their mega-projects ( Bertha, 520) are a separate issue.
You've once again perfectly summed up why I think you are an unconscionable asshole. Good day to you.
Realllly.............
Let's hear about how this works. Not to say it can't be done, but probably costs more than the TBM tool to begin with.
TBM's erect the walls inside the tube they drill using the most recently installed ring as a push platform. The cutter head has to be big enough to make a hole very slightly larger than the rings, so it can at most be backed up the distance it has bored since the most recent ring was installed. It wasn't that Hitachi Zosen made a boo-boo; it's an inherent weakness in ALL TBM's.