mdu
Active Member
I have a religion to introduce to you...
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DirectionNorth
Active Member
daniel_kryz
Active Member
I don't know much about engineering, but I can confidently say that they could've built each station consecutively (after the TBM passes through the station box).
On the other hand, politicians keep getting in the way
On the other hand, politicians keep getting in the way
crs1026
Superstar
It's easy to criticise when I don't know what was buried down there... but..... I really question the decision to deep bore using TBM's for so much of the route.
Perhaps a TBM was needed for some portion, but was that really the right decision?
And now we have four more projects that are TBM based.... again, while necessary in some places, is that really the right decision throughout?
Too late to change for this project, but I wonder if there should have been some detached and critical thinking done before those next four projects were launched. If you don't study history, you repeat the same mistakes.
- Paul
Perhaps a TBM was needed for some portion, but was that really the right decision?
And now we have four more projects that are TBM based.... again, while necessary in some places, is that really the right decision throughout?
Too late to change for this project, but I wonder if there should have been some detached and critical thinking done before those next four projects were launched. If you don't study history, you repeat the same mistakes.
- Paul
EastYorkTTCFan
Senior Member
That's not always possible as they usually use the completed tunnels to remove the dirt that is excavated by the TBM so having stations being built around that isn't always possible plus you also have the tunnel lining sections being delivered to the TBM as well.I don't know much about engineering, but I can confidently say that they could've built each station consecutively (after the TBM passes through the station box).
On the other hand, politicians keep getting in the way
Steve X
Senior Member
That's why they should get 6 TBMs to dig for the Crosstown. This cuts down time. Use Cedarvale as the launch site instead so the TBM could both started at the same place for liner delivery and dirt removal. If they dug the launch shafts all at the same time, they could have bored all 3 segments (Black Creek to Cedarvale, Cedarvale to Eglinton and Brentcliffe to Eglinton) at the same time. It'll take about 12 to 15 months to complete, completing in 2013/14. Then they could build each station in 3-4 years time pegging the opening date in 2017/18.
Instead they chose to spread out the cash flow in a decade and place all the digging at 2019/20 (beyond 2 election terms) and it won't complete before the next election. Now this try to make this decade long tunnel first and build later the regular way to build all projects.
Look at the Broadway Subway construction schedule: https://www.broadwaysubway.ca/construction/schedule/ They haven't even started digging and it'll open in 2025.
toronto647
Active Member
Crosstown LRT Updated Pictures between Eglinton and Sloane/Bermondsey and Eglinton and Jonesville (just west of Victoria Park). I assume Metrolinx will want to get as much work done as possible before the snow starts coming down hard in the next 3-4 weeks. Pictures from November 21 afternoon.
innsertnamehere
Superstar
Traditional road construction season typically ends mid-December and restarts mid-to-late March, so makes sense.
Almost odd seeing Eglinton not be a total construction mess for once.
Almost odd seeing Eglinton not be a total construction mess for once.
jcam
Active Member
Time to put on my ex-TBM designer hat. For soft- or mixed-ground geology like Toronto, the tunnel pushes off the lining as it installs it. Push TBM forward to mine -> pull back propulsion cylinders to make room behind machine -> install next ring -> push off the new ring. The 'muck' either gets taken out of the tunnel in a train (temporary tracks) or a conveyor.
For TYSSE, we had 4 machines, station boxes went in first, and the TBMS operated between the boxes. For Crosstown, tunnels were bored first, the, stations built after, essentially throwing out the tunnel where the stations went.
When you're in rock, like the Niagara power tunnel, you don't necessarily need a concrete liner, so the machine has pads that compress out on the sides of the already-mined tunnel, and push forward off that.
Last point on Crosstown, we built 2 of the TBMs early, as the intention was initially to send 2 tunnels to dig the LRT tunnel for Sheppard under the 404 to Vic Park, THEN send them down to Eglinton for the east drive. When that came off the table, the TBMs just sat in our shop for almost a year, and we delayed building the second 2.
smallspy
Senior Member
A lot of projects now look just as much as how life will be lived during construction as afterwards. (Whether this is the right approach? I don't know.) That's why TBMs and mining have become much more prevalent.
The first section of the YUS and the B-D subways were built as cut-and-cover. On the B-D, they were lucky and were able to use a parallel street for much of the length to prevent having to basically shut down Bloor and Danforth for years. But on the southern section of the YUS that wasn't possible, so Yonge was basically impassible for 4 years.
In the case of Eglinton, would we be willing to have that be the case? Would it be allowable to have the street unusable for that length of time (or maybe even longer)?
And before anyone remarks that "it's basically unusable now".....there is still a lot of traffic able to use the street today, and the street is still fairly vibrant around midtown and out towards Oakwood. If the line was built as cut-and-cover, there is no guarantee that it would be possible to maintain 2 road lanes all of the way across (such as around Yonge).
Dan
crs1026
Superstar
As I noted, I’m quite ignorant of what’s under the pavement, and what the alternatives were. Some of the stations were mined, and the two crossings of Line 1 were going to be major efforts anyway.
Is four years a dependable benchmark for a cut and cover project? Again, I don’t know…. I can accept it in the context of 1950s construction methods and Toronto’s first experiment with building subways. And conditions on Yonge, which might have had a whole different breed of underground obstacles. All I can say is that this particular traveller has been avoiding Eglinton for many years now…. Nd some of the congestion I experienced even while detouring certainly amounted to a closed road anyways.
I would just hope that there were good technical reasons for the added depths imposed both on construction and on the end product. I can buy tunnelling as a necessary evil, but given the impacts it should not be assumed - as it seems to have been with our latest projects.
- Paul
innsertnamehere
Superstar
B-D didn't use an existing street (well, it did on a few small sections), the vast majority of the line just expropriated 3-4 houses on every street to the north of Bloor and demolished them.
The TTC was planning to do the same thing on the north side of Queen for the then-planned Queen Streetcar tunnel that never came to be, and they also did it for Yonge between Bloor-Yonge and Eglinton.
ARG1
Senior Member
How much disruption can we reduce by doing stacked cut and cover tunnels (1/2 the width, but probably 1.5x the construction time)?
W. K. Lis
Superstar
Don't forget that it was cut-and-cover for the Crosstown stations. Notice how disruptive it was just for those station intersections and emergency exits. Then imagine the same disruption expanded for the entire length.
Northern Light
Superstar
From a report on Line 5 and Line 6 Fare Collection headed to next week's TTC meeting:
