We're generally used to seeing subway tunnels built (and used) side-by-side. They have built or stacked tunnels over each other. From link.

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^ I wonder if it really saves much in utility shifting etc. There will always be things under the middle of the road - sewers, mains, etc.

Can't imagine being able to actually use the road with that excavation in the middle, there would be shoring issues etc.

It's the station voids that are the big surface killers in our projects.

- Paul
 
JasonParis said:
To be honest, there's so much service already (or will be) north of Dundas West, I have to wonder if one would start canibalizing the other (GO RER, UPX, etc). I doubt we'd see the Relief Line go north of the #2 for a very long time into the future. Perhaps getting it to Eglinton, but even that seems a bit of a stretch.
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Agreed. and the TOcore plan really only allows massive amounts of density south of Queen. Obviously connecting what I'm going to start calling the Queen subway to Bloor makes sense, but extending past Bloor where it will probably always be low density makes no sense.
 
crs1026 said:
It's the station voids that are the big surface killers in our projects.

- Paul
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Agree.

That's why a short closing for the tunnel is not a big concern. TBM has no mid-block disruption, while cut-and-cover has a short one.

But by being shallow, the station construction time can be cut drastically, turning a 3 or 4 year excavation into maybe half.
 
... but the point of tunneling so deep is not just to avoid utilities - its to also cut down the noise. There is a 90 degree bend that will be running under houses - therefore its right that they are using TBM and putting it in bed rock (aka very deep).
 
Kitsune said:
... but the point of tunneling so deep is not just to avoid utilities - its to also cut down the noise. There is a 90 degree bend that will be running under houses - therefore its right that they are using TBM and putting it in bed rock (aka very deep).
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For relief Line, it makes complete sense, given the maze that is everything under Toronto's city streets. I think it's Relief Line North, the SSE, TYSSE, Crosstown, and potential YNSE and Sheppard extensions that could use some cut and cover.
 
Kitsune said:
... but the point of tunneling so deep is not just to avoid utilities - its to also cut down the noise. There is a 90 degree bend that will be running under houses - therefore its right that they are using TBM and putting it in bed rock (aka very deep).
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I thought the 90 degree bend at Pape required expropriation of a few home on either side of the Eastern/Pape intersection.
When the decision was that "money is no object", they switched to the Carlaw alignment that had to make several extra bends and go under a sewer.
 
^The game-changer for subway construction is the added number of vertical shafts for fire, ventilation, emergency egress, etc. as a result of changes to codes etc. TBM itself is innocuous, but one can't avoid the disruption caused by excavating these added shafts. And if the decades-old utilities are in the wrong place, one is screwed either way.

The wisdom of "keep it close to the surface" is unimpeachable. The deeper you go, the more costly it becomes.

There has been discussion here before about the potential for a rolling cut and cover using preformed tunnel shells, perhaps some kind of mechanical insertion similar to a TBM that runs in an exposed ditch (no risk of cavein if you excavate to expose the TBM beforehand!) I'm not an engineer but that is quite appealing to this layperson.

- Paul
 
nfitz said:
Near the Junction ... somewhere near Dundas/St. Clair/Keele I'd think. Which would raise the interesting possibility of terminating the 512 streetcar there.

In a fantasy world, they'd extend 506 up Parkside/Keele and terminate that there as well, and stop the Keele and Weston buses at St. Clair.

Normally when people talk about where they relief line should go next, the thought is always north or up the Weston tracks to Mount Dennis. But what about turning west there on either St. Clair, Dundas, or in between? It's got pretty good density to Jane. Mount Dennis will already be well-served with GO, UP, and the Eglinton line. Perhaps one day it can go west into Mississauga. Meanwhile turn Line 2 north to the Airport via Renforth station. I guess this is in fantasy map territory ... :)
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I've thought this before.

Dundas West would actually be a decent corridor for a subway route, if we densify the centre of Etobicoke greatly.

Send the Relief Line down Dundas West to somewhere near the 427, veer it south to terminate at Sherway Gardens.

Meanwhile, Line 2 can continue along the Milton Corridor (or perhaps along Dundas) into Mississauga to Dixie Station, to take advantage of the massive amount of growth that Mississauga is planning surrounding Dixie & Dundas, including what would become into the eastern terminus of the Dundas BRT.

Or perhaps send Line 2 to Sherway, and the Relief Line West to Dixie. There are multiple options.
 
facepalming_brooklynite said:
The Galleria Mall redevelopment does not look like low density to me:
http://urbantoronto.ca/news/2018/07/city-council-approves-rezoning-galleria-mall-redevelopment
I think it's clear that this development merits higher order transit, and if you're going north of Bloor at all it makes sense to connect to the St.Clair streetcar and the Eglinton Crosstown as well.
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Yes, I'm more referring to general corridors of density. The TOcore plan only extends to Bathurst, otherwise Toronto is mostly zoned low density.
 
If relief is needed fast perhaps the line could start off with a tunnel with just a Pape and Queen station only so it can open earlier and then add the extra stations later.
 
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