Toronto Ontario Line 3 | ?m | ?s

[gweed123]

Spadina Station. Can the station handle and increased load of people.

That's a good question. I suppose that most of the increase in ridership would be people who would otherwise be transferring at St. George to go southbound on University. So I guess it's really just a question of where would you rather have the congestion. By no means should this be a replacement for the DRL, but I think it would be quite effective as a 'local supplement' to it.

I also think that this type of route could give rise to an interesting local reference. Chicago for example has "The Loop" and "The South Loop", both of which are reference to the L loop in downtown Chicago. The Toronto version could be "The U", which would reference everything from Union to Bloor between Yonge and University, and "The Belt", which would reference everything from Spadina to the Lake to Parliament to Bloor. I think the phrase "inside the Belt" could become useful, seeing as how we have no real definition of what constitutes "the downtown area". By bounding it on 3 sides by an LRT line, it gives "downtown" a consistent and useful frame of reference. Just a thought.

 

[44 North]

So I did some basic research to add on to my previous post. I’ve begun to doubt the feasibility of tunnelling under the Don River for the (generally-accepted) eastern branch routing of the DRL. I cropped two images showing cross-sections of Toronto’s subsurface. Although both show a diagram of the Don Valley at – or south of – Queen, the subsurface deposits generally have similar widths northward to Danforth. It’s tens of metres of porous till followed by mixed clay (possibly porous/saturated), and a very deep shale bedrock surface. A tunnel would seemingly have to be a hundred feet deep or more.

When reading over this report on the Yonge North Extension concerning crossing the East Don River, it seems tunnelling below rivers is less feasible than many expect. http://www.vivanext.com/assets/files/enviroAssess/subways/yonge/updates/East_Don_River_Crossing.pdf

Stations on either side of the river for this section of Yonge would have to be 35m deep, twice the depth of our deepest station (Bayview at 18.6m). And considering planners add $1M for each metre of station depth, potential DRL stations on either side of the Lower Don valley (typically WDL and Broadview/Queen) would be very expensive. Add in second exits and the costs are insane.

What’s concluded as the most optimal alternative in the case of the Yonge extension is a bridge - shallower stations, reduced gradients, reduced groundwater pumping during and post-construction. It can be reasoned that these findings are easily carried over to the similar situation concerning the DRL’s crossing of the Lower Don.

So considering the costs of expropriation, built environment, and high residential/employment density, where in the Lower Don Valley is a bridge/viaduct feasible? One area: the large tract of parkland that is Riverdale Park East and West. Below is a basic alignment I thought up, where portals on the east and west side connect a 600m viaduct above the valley floor and its floodplain; as well as bridging the river, several rail lines, and the DVP. It’s just an idea for potential discussion, so I’m sure there are numerous problems associated with it.

 

[nfitz]

So I did some basic research to add on to my previous post. I’ve begun to doubt the feasibility of tunnelling under the Don River for the (generally-accepted) eastern branch routing of the DRL. I cropped two images showing cross-sections of Toronto’s subsurface. Although both show a diagram of the Don Valley at – or south of – Queen, the subsurface deposits generally have similar widths northward to Danforth.

North of Danforth is very different. The bedrock might be at the same elevation, but the overburden thickness is much greater (you may have noticed a hill from Danforth to the lake).

Exactly what is your cross-section from - it's hard to see details? Any hole I've seen along King, you quickly see the shale bedrock. You could easily see it at that hole for the new second subway platform at Union. You can see it right now in the foundation of the new Globe and Mail building near Front and Parliament. And you could see it in the holes they built recently for those 2 new condos at the intersection of King and River. I'm less sure what you'd have at Broadview and Queen - but I'd think it would be similar.

There may be a small piece right under the Don where it goes through overburden again. But that's not a big showstopper. They've tunnelled through this around 1930 making the main water supply tunnel out to the R.C. Harris Treatment plant. If they could do it then, they could do it now.

 

[44 North]

Cross-sections and their transect directions are from these two maps:
https://maps.library.utoronto.ca/dvhmp/maps.html
https://maps.library.utoronto.ca/dvhmp/Scans/G_3501_C5_1891_41G.jpg

The bedrock is fairly uniform across Toronto, but its surface topography does lower around the lake and major valleys. You can see this more clearly in the second map's cross-section...which I believe also shows the water distribution pipe you mention follow this dip. It's been gouged, scoured, and washed clean numerous times, Humber valley particularly. The Laurentian River traced the valleys well before any deposits from the last ice age. I'm quite certain the bedrock itself would be well fractured and loosened in these valley areas, and sections may be saturated and considered as part of the aquifer.

I'm not fully saying it can't be tunneled below the Lower Don. But it'd be a very costly and time consuming section. Significant dewatering, TRCA going nuts, very deep stations on either side...I just think there are easier and more realistic ways to do it.

 

[gweed123]

A question for everyone here to consider, especially given what 44 North has posted:

Does it really make sense to spend over $2 billion (4km of tunnel + spanning the Don to Thorncliffe Park) on a segment of track that will have 3 stations, 2 of which will likely be pretty low ridership stations? I mean, based on the map that 44North posted, would crossing at the point he selected, but then connecting at Broadview, followed by some type of surface alignment through the Don Valley to Thorncliffe Park not be a wiser use of funds? It would cut out about 3kms worth of tunnel, drop 2 lightly used underground stations, and remove the need for a massive new span over the Don further upstream. Cutting over $1 billion off the price tag of any extension north of the Danforth is nothing to sneeze at. The significant ridership stations on the DRL will be every station west of the Don, the transfer with Bloor-Danforth, Thorncliffe Park, and Eglinton. Anything else is just there to fill in the gaps, and won't significantly add to the total ridership of the line.

Just some outside-the-box thinking here. I commend 44 North for trying to challenge the "assumed" alignment, and I just thought I'd do the same.

 

[nfitz]

I'm not fully saying it can't be tunneled below the Lower Don. But it'd be a very costly and time consuming section. Significant dewatering, TRCA going nuts, very deep stations on either side...I just think there are easier and more realistic ways to do it.

I disagree. It's as simple as selecting the right equipment for boring. Dewatering may not be necessary except at stations. The lower Don is hardly a very natural environment. They were using a TBM in the West Donlands recently for the new sewer connection from near Mill Street to right near Keating Channel - this didn't create any issues I've heard of.

 

[P23]

People in Toronto get whipped into a frenzy over elevated rail, if you proposed elevated rail through a park they would probably burn down city hall.

 

[TheTigerMaster]

I already have my torches ready

 

[robmausser]

Elevated rail killed my father.

 

[44 North]

I disagree. It's as simple as selecting the right equipment for boring. Dewatering may not be necessary except at stations. The lower Don is hardly a very natural environment. They were using a TBM in the West Donlands recently for the new sewer connection from near Mill Street to right near Keating Channel - this didn't create any issues I've heard of.

Yes, boring below rivers or through permeable, saturated watersheds is entirely possible. Breaches can be remedied by plugging, pumping, and things would be back to normal within days. But this isn’t a harbour or broad river like the Thames. A heavily-used expressway and freight/commuter line literally abut the river, and are damn-near close to water level. If any significant breach were to occur, the potential surface subsidence could grind the entire Lower Don Valley corridor to a halt for months. Does an enormous rapid transit tunnel (or twin tunnels) have the same level of safety requirements as a small water distribution or sewage line?

Perhaps I’m making a mountain out of a molehill and this is all easier done than I’m making it out to be. I'm looking forward to when more specifics of the DRL are released which will make more sense of the alignments.

A question for everyone here to consider, especially given what 44 North has posted:

Does it really make sense to spend over $2 billion (4km of tunnel + spanning the Don to Thorncliffe Park) on a segment of track that will have 3 stations, 2 of which will likely be pretty low ridership stations? I mean, based on the map that 44North posted, would crossing at the point he selected, but then connecting at Broadview, followed by some type of surface alignment through the Don Valley to Thorncliffe Park not be a wiser use of funds? It would cut out about 3kms worth of tunnel, drop 2 lightly used underground stations, and remove the need for a massive new span over the Don further upstream. Cutting over $1 billion off the price tag of any extension north of the Danforth is nothing to sneeze at. The significant ridership stations on the DRL will be every station west of the Don, the transfer with Bloor-Danforth, Thorncliffe Park, and Eglinton. Anything else is just there to fill in the gaps, and won't significantly add to the total ridership of the line.

Just some outside-the-box thinking here. I commend 44 North for trying to challenge the "assumed" alignment, and I just thought I'd do the same.

Well, I definitely thank you for being commended. I’d be glad if this idea spurred some outside-the-box thinking. And although I fully believe any cost/time savings on a DRL should be pursued, I also don’t want it to be minimized in importance or potential. Politicians 30km away in Markham and Richmond Hill have been pushing for a quick-fix DRL so as to fast-track a Yonge North extension. But the DRL is too critical of a line to be curtailed, and there are areas southeast of the valley which have high redevelopment potential. Also, the valley is quite broad, doesn’t follow a straight path, carries important infrastructure, and has many smaller ravines and valleys branching off which further complicates things.

However, as many know there have been a few ideas about using the Don Valley, albeit vague ones:

The TC Don Mills LRT was looked at as potentially using the Don Valley southward from Overlea and connecting somehow at Castle Frank. I don’t think it’d work. Then there was a (recent?) report from Metrolinx that briefly mentioned a Don Valley light RT – forget when/where this was mentioned. As well there’s Metrolinx’s purchase of a key section of the Bala Sub, which currently is a derelict corridor running from the Lower Don to Leaside. Although the Bala Sub doesn’t use the whole extent of the valley like the Richmond Hill line, the section that does is much more direct in its path. My next map will probably take into consideration this abandoned rail line and its "Half Mile Bridge".

 

[gweed123]

Well, I definitely thank you for being commended. I’d be glad if this idea spurred some outside-the-box thinking. And although I fully believe any cost/time savings on a DRL should be pursued, I also don’t want it to be minimized in importance or potential. Politicians 30km away in Markham and Richmond Hill have been pushing for a quick-fix DRL so as to fast-track a Yonge North extension. But the DRL is too critical of a line to be curtailed, and there are areas southeast of the valley which have high redevelopment potential. Also, the valley is quite broad, doesn’t follow a straight path, carries important infrastructure, and has many smaller ravines and valleys branching off which further complicates things.

However, as many know there have been a few ideas about using the Don Valley, albeit vague ones:

The TC Don Mills LRT was looked at as potentially using the Don Valley southward from Overlea and connecting somehow at Castle Frank. I don’t think it’d work. Then there was a (recent?) report from Metrolinx that briefly mentioned a Don Valley light RT – forget when/where this was mentioned. As well there’s Metrolinx’s purchase of a key section of the Bala Sub, which currently is a derelict corridor running from the Lower Don to Leaside. Although the Bala Sub doesn’t use the whole extent of the valley like the Richmond Hill line, the section that does is much more direct in its path. My next map will probably take into consideration this abandoned rail line and its "Half Mile Bridge".

I definitely see your point regarding the 'cheapening' of the DRL. However, I would venture to say that the key areas that any DRL alignment NEEDS to hit are as follows: downtown, downtown shoulder east, easy connection point at Bloor-Danforth Subway, Thorncliffe Park, Eglinton LRT. Anything else is really just filler. If you can find an alignment that hits all of those areas, and minimizes cost, why not at least examine it?

The alignment that you proposed and that I refined above would hit all of those areas, and eliminate the need for over 3km worth of tunnelling. The cost? Dropping 2 lightly used stations from the alignment (Gerrard Square and Cosburn). The former can be mitigated by putting in a GO REX station at that location, and the latter can be solved by extending the Broadview streetcar north to some sort of a loop around that area. Both of those would come to a fraction of the cost the subway stations + tunnels that would be required.

 

[WislaHD]

Would be interesting incorporating a Don Valley LRT with the Parliament LRT discussed in previous pages. (Even connecting all the way to the East Bayfront LRT?)

 

[44 North]

So I made a design which hits all the areas Gweed mentioned. It utilizes the Don Branch of the <strike>Bala Sub</strike> Belleville Sub and a redesigned Half-Mile Bridge from just north of Broadview station to about Laird Dr. Although the route looks a bit wonky, it is more direct than if it were to somehow use the Richmond Hill line. East of Thorncliffe Park station the line descends underground below a hydro corridor and uses another bridge to cross the West Don River, before reentering the valley and intersecting with Don Mills station.

Three large bridges, a significant portion running in the open air, shallower stations, Leslieville and south East York not served... Clearly there are pros and cons. But are there cost savings? Is it realistic? Would NIMBYs be opposed? Who knows.

Edit: Perhaps what I'm calling the "Bala Sub" is actually referred to as the Don Branch or Leaside Spur or Havelock Line. And I guess Metrolinx has looked at this particular routing as its mentioned here: http://www.metrolinx.com/en/projectsandprograms/reliefstudy/YRNS_Long_List_for_Consultation_EN.pdf
Double Edit: Yes, fucked it up. It's the Don Branch of the Belleville Sub. I believe Metrolinx does own it.

 

[nfitz]

A subway to the Brickworks. That's a first. But not stop ... oops.

 

[WislaHD]

Never have I ever considered a subway at the Brickworks.


That is admittedly not my ideal route. For starters, I would've used the Castle Frank routing (with displeasure towards the loss of parklands), and Thorncliffe station is in the land of big box stores far away from walking distance of those super dense residential towers. Ideally we can hit Flemingdon Park on the way to the Eglinton-Don Mills station as well.