Rainforest
Senior Member
The Canadian runs 3 times a week, and it is essentially a tourist train based on the ticket prices. If it has to stop using Bala sub, and take a slightly longer route to Union instead, the skies won't fall.
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Ontario Line North of Eglinton (was Relief Line North) (Speculation)
- Thread starter jaybe
- Start date
BurlOak
Senior Member
The question is: If instead of spending the effort to build the decking - which also involves piling and foundation work to support the beams - they would spend the time digging down an placing a precast box tunnel; would the road closure be similar, but the tunnel would be complete instead of having work continue below the decking to complete the tunnel.That'll mean cut-and-cover along the north section of Pape Avenue to the side of the Don River Valley, just like what was done with the original Yonge Subway.
Diverting the the traffic as they dig down.
From link. Missing would be all the 3+ story buildings along Pape Avenue.
The tunnel would be a W shape and an M shape precast segment - with a field cast high early strength concrete closure to connect W and M together to create a 2 cell tunnel. Each W and M would be about 3m long (the width of a traffic lane for transportation) and 2.5m high (to fit under bridges for transportation) and 10m wide (to create a tunnel cell to accommodate a 3m train and 1.5m emergency walkway). When Yonge subway was first built, there was no such thing as precast concrete and no such high early strength concrete. With these modern advancements, I see no need for decking over - just dig, place precast segments, waterproof and backfill. Each stretch would be closed for less than a month. The only part that needs decking is the stations (just as when a TBM is used) - but with with cut-and-cover, the stations would be much shallower, so construction time is much reduced.
jaybe
Active Member
This sounds so manageable. All proposed DRL routes north of the Danforth could accommodate this construction methodology rather than drilling. I live in the area would gladly put up with the inconvenience for the cost savings and quicker completion.
Especially under a street like Don Mills, where closing the two middle lanes wouldn't mean a total shutdown. I can see the merit of doing it under a more urban roadway, but under a wide suburban arterial I think it makes more sense to do cut and cover.
W. K. Lis
Superstar
Except that cut-and-cover is fine with shallow digs. The problem is sound or vibration of passing trains. The deeper the cuts, the less vibration is carried or the more material that can absorb that vibration.
See link.
BurlOak
Senior Member
There seems to be all sort of isolation methods of having some ballast under track, rubber isolation of tracks and ties, and energy absorbing ties. You are potentially saving $100's of millions of dollars per km, so you would expect that you would have to spend a few million more on the tracks.
44 North
Senior Member
Hold on though, let's not forget RH Express. Which had quite high projections when modeled for the Big Move, so not exactly speculative. Something was drawing riders to it. With the "express" aspect one would assume no stopping south of Langstaff Rd, which could be an optimal operation to go in tandem with a milkrun from Bloomington. And as is RH has pretty solid ridership per km, more than others getting hefty investment.
This summer we toured QP and on the second floor you could hear/feel the subway. Which was extraordinarily surprising for me, knowing that U/S is deep bore thru that stretch, and that I was +30ft above ground level in a stone castle. Though perhaps the deep foundation and stonework helped carry the vibrations.
But agreed. Precast segments in a cut/cover operation could be beneficial for certain segments. Basically a small moving construction project instead of a decade-long one stretching several km.
Uncle Teddy
Senior Member
You can hear the downtown subways in all sorts of places downtown. That's what happens when they are close to the surface.
mdrejhon
Senior Member
There's also the potential theoretical concept of interlining DRL with Richmond Hill RER. (Meaning DRL becomes the RH RER)
Option #2 and #3 permits this potential concept:
Which would make this or this possible -- the interlining of DRL to Richmond Hill RER.
An interchange station at Langstaff GO that connects 407 Transitway and two subways (Yonge North extension + Relief Line meeting at Langstaff GO or Richmond Hill).
Depending on corridorwidth south of Langstaff, there could be a parallel track left to allow Northlander / expresses / other trains to reach Union.
But the concept of merging DRL + RHRER is actually one of the possibilities suggested (and may be attractive to the current provincial administration and/or Superlinx)
Attachments
44 North
Senior Member
Pretty sure something along these lines has been the last twenty pages of discussion. But if relating this to the 2008-era RH GO Express proposal, wonder if there could be benefit for a 3-track RL. So two tracks with all-stop no different than every TO subway project since 1954; third track allowing station bypass. Why 3-track and not 4? Obviously majority are core-bound in AM, and outbound in PM, so basically the 3rd/Express track would be bidirectional depending on time of day. If in a deep tunnel setup probably two tracks above and the single track below, or vice versa.
micheal_can
Senior Member
How do you get all those trains to their starting point? With only 3 tracks, you do not have the space to have enough trains express and local.
nfitz
Superstar
Look at the average speed they used. It's the same as the other routes - which doesn't seem unrealistic! Who knows what erroneous data was in that! Instantaneous connections to Line 2 and Line 5 no doubt!
Hard to say really without a table of all the link times and node locations.
PeterCh
New Member
Minor comment:
I thought the storage tracks north of Danforth under Pape will be TBM cut because of their depth?
Excuse me if I've missed something because I haven't gone through the whole thread.
There are some diagrams in a Steve Munro blog, where the wording is a bit unclear if one doesn't follow closely. Areas on a couple diagrams marked in yellow are cut and cover where the "Y" joins to the shallow Bloor-Danforth line. But the storage tracks under Pape, although marked in yellow on one diagram, are deep -- The top of the tunnel would be something like 25 m underground. There's a TBM extraction shaft planned, but Pape I don't think would be cut and cover all the way.
(Ref.: https://stevemunro.ca/2018/04/29/relief-line-south-station-and-alignment-plans/ - last few diagrams at page bottom)
It's my neighbourhood so I was looking closely at the details.
nfitz
Superstar
That's a pretty major comment!
Interesting ... looking at the depth of the tunnel, you'd think it would be TBM that's for sure - with the tunnel floor over 30 metres below ground surface.
But looking at the cross-sections and plans in Appendix 3-3 of the August 2018 Environmental Project Report, it shows the bottom of the tunnel south of Danforth as being "BOTTOM OF TWIN BORE TUNNEL" but north of Danforth to Mortimer it says "BOTTOM OF BOX". Also the plan shows EXTRACTION SHAFT #2 at Pape and Danforth at the south end of the new station - but no extraction shafts further north. Steve Munro's page shows the same thing actually!
Ah, if you look at the text itself in Section 3.3, it's very clear that everything north of Danforth is cut-and-cover. If you look at the cross-sections, chainage 6+550 (6.55 km) is at Danforth while 7+410 is the end of the tunnel at Westwood Avenue just north of Mortimer.
On page S3-22 of the report (in Section 3.3) in the section called "Tunnel Drives" is a paragraph that says:
"The remaining alignment from 6+650 to 7+410.36 would best be constructed using cut and cover method due to cross over and tail track three track design required to use a storage for subway cars on the Relief Line South."
TransitBart
Senior Member
I would walk farther to faster transit. I get @Streety entirely.