Millennium Line - Evergreen Extension | Completed

[xd_1771]

If anyone's curious about the Mark IIIs (Bombardier Innovia METRO 300), the report previously released by Bob Mackin said that the first Mark IIIs will be delivered before the end of the year (in the latter half), and the final vehicles (not the prototype I showed earlier) are being manufactured.

The first Mark IIIs for Kuala Lumpur's Kelana Jaya extension are slated to come even earlier. We'll be seeing those first.

[Ridgerunner]

[QUOTE=Alex Mackinnon;7062731]Ridgerunner, I think you're reading into this a lot more than you should.

If they could just drive along without having to do maintenance, then there wouldn't be an issue. The ground would be confined and there most likely wouldn't be any subsidence. Unfortunately, they've got to stop on occasion.

End Quote


Does anyone remember the two tunnels on the Canada Line? Both were much longer than the present work that has been done on Evergreen. The two tunnels bored under water on the first leg and had no issues at all with "having to stop on occasion" .

The evergreen tunnel is stopping every 50 feet for such maintenance ... which is Poli-Speak for "we ran into another sand lens we did not anticipate and we have to make sure that the one or two homeowners don't get disturbed even a little bit".

I still believe that i am reading this right. The issue is politics not technology.

[queetz@home]

Originally Posted by Ridgerunner

The issue is politics not technology.

You are right about politics. The issue here is the powers to be, solely for political reasons, forced the Canada Line ahead of the Evergreen Line, and did so, let the stakeholders affected by it be damned. This resulted in a lot of issues we see today from the smalll Canada Line platforms, to the stigma of cut and cover, and to the current Translink financial "issues". But this also yielded a much more sensitive public. Not wanting a repeat of the Cambie Merchants mess, EGRT is far far more sensitive to people that are directly affected by the construction such as residents and businesses. Due to the effects of politics, EGRT has practically been overkill when it comes to treating the affected stakeholders, and the tunneling process has been affected by it.

They cannot work as fast or as much as they could (i.e. 24/7) and have to ensure that they are doing everything that they can do avoid any sort of sinkholes (but failing). Note that even though sinkholes have formed, they are quite small (unlike those large ones in Ottawa and Los Angeles subway construction) and frankly, not that big a deal. But because of politics that goes back to a certain former transport minister who shall not be named, EGRT has to treat the residents and businesses like royalty even when its not necessary. And the negative impact of politics will still carry on in future projects such as Surrey and Broadway rapid transit.

As for technology, I am no expert but I think the reason why EGRT is more prone to sinkholes than Canada Line's boring is the size of the TBM itself. The bigger it is, the more prone it would be in making an impact. Even if air pockets developed during the Canada Line tunneling, its still fairly small its possible that it would simply be a non-issue. Evergreen Line's TBM is huge, and no doubt the risks are much greater.

[Olden Retreiver]

Originally Posted by finalcoolman

I am the only one with real information, I posted back on May 7th that actual tunnel boring will resume around Canada Day.

Since you're the only one on this forum with real information, could you please tell the rest of us if anyone on the tunnelling project has actually got a clue? Thanks in advance.

[finalcoolman]

Originally Posted by Olden Retreiver

Since you're the only one on this forum with real information, could you please tell the rest of us if anyone on the tunnelling project has actually got a clue? Thanks in advance.

Well, the problem is that Clarke Hill/Burnaby Mountain is probably the worst area in the entire Lower Mainland you could build a tunnel in. Probably the only place that could be worse, is if you were crazy enough to bore a tunnel in the water logged mud flats in South Delta/Richmond. I want to emphasize that even if we bored a single bore tunnel for both tracks in the Broadway corridor with a similar TBM to Alice it will not be this bad, since Burnaby Mountain is nothing more than a mound of loose sediment (glacial till) left behind by the glaciers in the last ice age.

The TBM has been stopped since March when it arrived at its present location at Seaview. They stopped the TBM just a couple of meters before a grout wall that was already under construction since the beginning of the year. The TBM was NOT stopped flush with the grout wall at this time, as to not damage the TBM from the grout wall construction. However no maintenance was done for MONTHS, because the project team was scared to hell of creating a sink-hole under Clarke Rd and all the bad publicity from it. So they spent almost half a year (basically from the new Year until the beginning of June) building the strongest/highly reinforced grout wall they could. On June 5th, the grout wall construction was completed, and the TBM was moved just a couple of meters forward to become flush with the grout wall, and it was hoped that when they opened the door into the maintenance chamber, the wall that they spent 5 months building which was now butted butted against the head of the TBM, would hold up all the loose sediment, and prevent a sinkhole from forming.

Well, even 5 months of building a wall couldn't hold up all the incredibly loose sediment this hill is made from. So in terms of competence, maybe if they spent longer building a even more reinforced wall, the sink-hole wouldn't have happened.

But then it becomes a time-cost-benefit issue. They could have spent 10 months instead of 5 building a even bigger and stronger grout wall, but then TBM maintenance would not begin until October. Is that extra time of the TBM just sitting idle until October worth it just so no sink-hole appears?

Or you can look at it this way in terms of competence. Five months of building a grout wall and we still got a sink hole that shut down the road to traffic. They could have skipped building the grout wall all together, just shut down all traffic EXPECTING a giant sink hole with concrete trucks lined up and ready, and gotten it over with quickly, and the TBM will be almost done now.

Anyways the actual TBM maintenance is in progress now, and should be complete around the end of June/beginning of July, with the TBM starting up again to proceed to Robinson at that point in time.

[Alex Mackinnon]

Originally Posted by Ridgerunner

The evergreen tunnel is stopping every 50 feet for such maintenance ...

I still believe that i am reading this right. The issue is politics not technology.

Nope still wrong. They had to stop and change tools on the Canada Line. They had 2 station boxes, which are just dandy for getting at the exterior of the machine. They also hit sandstone, so they could open up the face and perform maintenance. They would have done maintenance twice on each direction of the bore while in the station, plus whatever they did when they encountered competent sandstone. Evergreen only has grouted safe havens.

Article on Canada Line TBM tunnel.

And as finalcoolman said, this is the same round of maintenance.

Also, you all should stop making assumptions about the geology. It can change quite rapidly.

[Olden Retreiver]

Right after the 4th sinkhole, I was going to post facetiously that they should get back on schedule by skipping the grout and going directly to sinkhole.

Initially I thought the grout was intended to strengthen the ground by essentially flooding a volume of soil with cement material. What is the designed purpose of this (vertical?) grout wall? Isn't the basic problem that the tunnel roof keeps collapsing whenever it's unsupported? Is the grout wall intended to hold back groundwater flow? Inquiring minds really, really want to know.

[Jimbo604]

Is anyone going to the following? They will be discussing plans for south of Robinson, my question is when will TBM arrive at Robinson?

"EVERGREEN LINE RAPID TRANSIT PROJECT Community Information Open House
Wednesday, June 17 - 6:00 p.m. – 8:00 p.m.

Dear Resident,
On Wednesday, June 17 the Evergreen Line project team will hold a community open house to provide information on tunnel boring operations at Clarke Road, south of Robinson Street. The meeting will be a drop-in open house format and residents will have an opportunity to speak directly to members of the project team. You are invited to attend the following meeting:
DATE: Wednesday, June 17
TIME: 6:00 p.m. – 8:00 p.m.
LOCATION: Banting Middle School – 820 Banting Street, Coquitlam"

Source:
http://www.evergreenline.gov.bc.ca/docum..._Invitation-CommunityMeeting-17jun15.pdf

[finalcoolman]

Originally Posted by Olden Retreiver

Right after the 4th sinkhole, I was going to post facetiously that they should get back on schedule by skipping the grout and going directly to sinkhole.

Initially I thought the grout was intended to strengthen the ground by essentially flooding a volume of soil with cement material. What is the designed purpose of this (vertical?) grout wall? Isn't the basic problem that the tunnel roof keeps collapsing whenever it's unsupported? Is the grout wall intended to hold back groundwater flow? Inquiring minds really, really want to know.

The purpose of the grout wall IS to hold up the ground to prevent sink holes. Nothing to do with stopping water, that is done by a separate dewatering process to lower the water table.

Listen, if you go to a sandy beach, fill up a bucket of sand and plop it upside down to create a little sand mountain, this is how cohesive Burnaby Mountain/Clarke Hill is. The only thing holding it all together is gravity. Now imagine trying to bore a miniature tunnel through that little mountain of sand you got.

I will let you guys judge what is or is not incompetence yourselves through the following information. First of all I want to make clear, that having to build a grout wall in of itself is NOT a sign of incompetent tunneling in any way. When you are tunneling through glacial sediment, building a grout wall is the only chance you have of keeping the soil stable for TBM maintenance and not getting sink holes.

The problem is, the project was building the tunnel through this soil condition WITHOUT building grout walls, hoping to just wing it through the TBM maintenance and hope that no sinkholes appear. This has the benefit of saving ALOT of cash by not having to build any grout walls, and being able to say in the literature that the only tunnel construction disturbance would be at both ends of the tunnel.

The whole reason for the tunnel delay, is that building grout walls wasn't planned for in the time schedule. For example, the TBM arrived at Seaview in March, but was sitting idle waiting for maintenance after the grout wall was completed in June. If the grout wall was already complete by the time the TBM got there in March, there would have been no delay at this maintenance stop (ignoring the fact it was already delayed from the previous stops).

The tunnel could have been completed on schedule if they started construction of the grout walls in the beginning of 2014, with each wall being complete before the TBM got there, letting TBM maintenance begin immediately, and not having the TBM just sit there a couple of meters before the wall waiting for its completion.

But the problem is, the project wanted to save some serious cash by not building the walls and hoping for the best. Well as you all know, even building these walls at the last moment, we still got sinkholes. So it begs to ask the question:

It is pretty obvious that building these walls for 5 months at a time is some serious coin. Would it just be cheaper to forgo the walls, let a huge sinkhole appear, and repair it. Ofcourse the 4th sinkhole would be much larger, than the one that appeared if no wall was constructed. It might have been so large that it may have damaged some other structures. But, it could have been cheaper to just pay off the property repairs, than 5 months of subterranean construction.

[twoNeurons]

They had soft soil when building the Seikan tunnel. TBMs ( at least at that time ) didn't work... so they built it by hand:

• Video Link

[Olden Retreiver]

Several points:

1. I cannot see how building a grout "wall" can hold up the tunnel roof. They should be building grout arches over the top instead.

2. The grout walls do not hold up the tunnel roof - it collapses repeatedly, causing sinkholes.

3. Therefore I can't stop wondering if I'm smarter than the people building this tunnel.

[aberdeen5698]

Originally Posted by Olden Retreiver

I cannot see how building a grout "wall" can hold up the tunnel roof. They should be building grout arches over the top instead.

I assumed that the idea was to create a mostly-solid mass of grout that the TBM would bore partially into. When the cutting face backs away the grout would be above and around the cavity rather than loose soils.

[Alex Mackinnon]

Originally Posted by Olden Retreiver

Several points:

1. I cannot see how building a grout "wall" can hold up the tunnel roof. They should be building grout arches over the top instead.

2. The grout walls do not hold up the tunnel roof - it collapses repeatedly, causing sinkholes.

3. Therefore I can't stop wondering if I'm smarter than the people building this tunnel.

Re 3: I think Dunning and Kruger would say you're not since you're overly simplifying the problem.

The grout is injected into sand to attempt to make solid mass that won't flow or fall in on the crews working in the cutter head.

The grout "wall" isn't just a vertical wall, it's like a block. They pump an area full of cement, then drive the TBM into the middle of it. If the cement and sand made a solid block, then the contractor could back up the TBM a little bit, and have room to work on the cutter head, without having the original sandy material fall in, or causing a cave to form.

The problem is the grouting. It's basically a blind process. Once you start pumping concrete, you don't know where it's actually going. There's tools called packers than make it so you can isolate vertical sections of your injection hole, but that's about all the control you get.

Ideally your grout would form nice cylinders or pancake shapes as you inject from surface. Overlap a bunch of these and you could make a safe haven for the TBM. If grout flows in directions that aren't useful, then you can find that injecting a lot of grout does nothing.

[nname]

Originally Posted by dpogue

They've started putting up the wayside signs around Lougheed (with a slightly different font that is going to irk me to no end). One on the outbound curve is already facing the wrong way.

Same font used on the Canada Line wayside signs?

The signs are up at the Burquitlam area too. Seems like the switch before the station would be numbered 200-203.

[officedweller]

I think this is an explanation of the grouting:

http://www.haywardbaker.com/WhatWeDo/Techniques/Grouting/CementGrouting/default.aspx

A "grout wall" appears to be a "term of art" - and should not be taken literally as a thin "wall".

[deasine]

Originally Posted by dpogue

They've started putting up the wayside signs around Lougheed (with a slightly different font that is going to irk me to no end). One on the outbound curve is already facing the wrong way.

Any photos?

[dpogue]

Originally Posted by nname

Same font used on the Canada Line wayside signs?

The signs are up at the Burquitlam area too. Seems like the switch before the station would be numbered 200-203.

I am ridiculously curious about the switch numbering, and will be stopping by Burquitlam over the weekend to see if I can get a good view from the ground

Originally Posted by deasine

Any photos?

I have a video approaching Lougheed from yesterday and a video departing Lougheed from today.

The new switch signs are DC158, DC157 (on the side platform facing away from the camera), and DC155.

[GeeCee]

News1130 report on the latest open house: http://www.news1130.com/2015/06/18/next-...ings-old-worries-into-new-neighbourhood/

The tunnel boring will start in late July, expected to last three months, ending at Clarke Road and Robinson Road for machine maintenance.

[Olden Retreiver]

Originally Posted by officedweller

I think this is an explanation of the grouting:

http://www.haywardbaker.com/WhatWeDo/Techniques/Grouting/CementGrouting/default.aspx

A "grout wall" appears to be a "term of art" - and should not be taken literally as a thin "wall".

Well, whatever they built, it doesn't work.

And if they can't get this right after 4 tries, it legitimizes all my questions and those of Port Moody Mayor Mike Clay. In my general experience, Engineers can do just about anything if they have the right tools and the right input information. Is EGRT working with fundamentally incorrect geotechnical data and interpretations?

[GeeCee]

Originally Posted by Olden Retreiver

Is EGRT working with fundamentally incorrect geotechnical data and interpretations?

Depends on what you consider to be 'fundamentally incorrect'. They're basing their actions over the results of their test bore holes. They could have drilled holes every five feet or so to get a more accurate picture of the ground conditions, but that would have raised the costs and duration of that part of the project considerably. The perfect tool in this case would basically be x-ray vision. They certainly could have used that in Seattle a few years ago as well. But, since we don't have that, sample drilling every so far is the name of the game.

Sinkholes happen when you're tunneling. They can occur when tunneling due to insufficient data or incorrect assumptions, but given the soil conditions, I wouldn't think that the possibility was ever entirely ruled out.