Bojaxs
Active Member
Yeah, I was under the impression that a line requires 3 tracks in order to run express service. Hence why I was disappointed to see the Davenport Diamond guideway was only constructed wide enough to accomodate 2 tracks.
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GO Transit: Construction Projects (Metrolinx, various)
- Thread starter drum118
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crs1026
Superstar
^ It half works if the Stouffville line runs "wrong main" - ie eastward trains on the northmost track - because then westbound locals can be interwoven on the second track.
Presumably LSE will remain three tracks from Scarboro Jct out to Guildwood, which puts us back to 1967 in terms of track capacity for LSE..
ML has gradually walked back the investment in track that was supposed to happen east of Guildwood. The big losers in all of this will be VIA, and anyone hoping for an express GO ride west of Pickering.
The added investment of a flyover(under?) and further capacity east of Guildwood is a very prudent investment imho. If this has been cancelled, I'm not impressed.
- Paul
Presumably LSE will remain three tracks from Scarboro Jct out to Guildwood, which puts us back to 1967 in terms of track capacity for LSE..
ML has gradually walked back the investment in track that was supposed to happen east of Guildwood. The big losers in all of this will be VIA, and anyone hoping for an express GO ride west of Pickering.
The added investment of a flyover(under?) and further capacity east of Guildwood is a very prudent investment imho. If this has been cancelled, I'm not impressed.
- Paul
Reecemartin
Active Member
This is not really a change from the status quo, in sections with four tracks - i.e. from Union to Scarborough, you have Stouffville make most stops while LSE skips (thus effectively always running "express") on the inner section, beyond Scarborough you are in the same place you are today.
But, to be clear 2 tracks is fine for express trains and is just how express trains work on the large parts of the Paris RER and in rail systems across Asia - select stations have overtake tracks where expresses pass stopped locals + there is remaining triple track which could be expanded, you can also have some trains run express for parts of their journeys until they catch a leading train. This is enough to run a fairly high frequency of both local and express trains, the main drawback is you can't have some number of Stouffville trains become expresses when they hit Scarborough by popping onto the express tracks.
There is on one hand a reliability cost where if one track goes down you can't put all trains onto the local or express track easily, but on the other hand having a ton of trains switching from local to express tracks is going to lead to a ton of reliability and scheduling issues anyway (just look at the NY subways issue with merge conflicts etc, and GO trains are bigger and slower, even if EMUs).
This is not the plan and frankly is the kind of thing that would create a lot of delays and conflicts at the junction, as well as confusing ops on Stouffville, and for no substantial benefit when the interleaving is of locals and we are prepping for a fourth track anyways.
All of this stuff is kind of water under the bridge at this point, they've been planning to do it for at least 3 years since I did that interview.
ShonTron
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The JR line between Nara and Kyoto has only one mainline track (and passing sidings) and it has local and express service.
You only need more than one track per direction at places where trains running in the same direction need to pass each other. The Davenport Diamond viaduct is not one of those places.
crs1026
Superstar
Well, today it’s the Stouffville trains that skip stops, but I would be happy if LSE did the skipping and Stouffville became the local route.
True, but ML is not adding overtake tracks, and have deferred any plans to extend the triple track.
Can you explain how the existing third track can be used as an overtake track for express trains in both directions without requiring them to reduce speed to take turnouts (which would greatly work against overtakes in the short stretch between Scarboro and Guildwood) ?
Nobody said that ML’s decisions only got bad lately. If this one merits heritage designation, that’s fine - but it’s a very limiting thing for the service plan.
- Paul
nfitz
Superstar
Lakeshore East was only 2 tracks east of about Pape until about 2010 or so. And it ran express trains AND Stouffville service at Peak.
You'd surely need 3 though if the express trains were running in both directions, and if the counter-peak service was very frequent.
Bojaxs
Active Member
That was my thinking. If we want AD2W on a line with 15-30 min frequency (in both directions), while also running commuter express service on that same line, then we would need a third track. Wouldn't we? I mean maybe if you have a really experienced transit controller at the helm, they could make it work with enough bypass tracks. But at some point, if you keep adding bypass tracks to a line, doesn't it make more sense to just add a third track?
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Reecemartin
Active Member
Stouffville being quite a bit shorter (especially when demand weighted) certainly makes more sense as the local.
Lots of things are possible and the specific track layout has not been determined, that's what the whole design and development phase is about. From what I hear through the grapevine lots of higher speed turnouts are coming. Re. how third track can be used you just have to offset the overtakes in the service plan sort of as Sean said.
It is and it isn't, this decision strongly bifurcates LSE and STO, as I said before its not probably what I would choose but it should make operating very high frequencies (as opposed to a mix of patterns at lower frequencies) fairly simple and by all accounts thats what we are going for..
Reecemartin
Active Member
A third track is frankly often going to be less useful than short sections of quad track for overtaking, by its nature a third track is best suited to an asymmetrical service pattern and thus is often going to have a poor capacity cost benefit.
nfitz
Superstar
Do you have any papers and numbers to back that up?
crs1026
Superstar
The LSE service plan at peak as shown in the GO Expansion Business Case is five express trains per hour plus four stopping trains. (It's very likely that this plan has been changed somewhat, but as it's the most authoritative plan we've seen......)
A local train leaving Union on the markers of an express has only eleven minutes' head start on the following express train.
One assumes that all trains will stop at East Harbour, so the local has to be spaced slightly further behind the express, otherwise it will have to hold short of the platform at EH while the express makes its platform stop. So maybe nine minutes behind. It won't take long for the next express train to catch up.
There is no space for construction of overtaking sidings at Danforth, and construction is far enough along there that we can conclude there won't be any built there.
Now add even a single VIA train to the mix....
At fifteen minute headways each, LSE and Stouffville can easily share a track for stopping service in at least one direction, and turnout speeds for local trains are less restrictive assuming trains are making a platform stop at Scarborough, and/or are proceeding at the lesser speed implied by the curves on the Uxbridge Sub just north of there. That adds some routing conflicts, granted, but still seems the better design.
- Paul
smallspy
Senior Member
They're not. They've standardized on the #20s.
There are locations currently that have some slower-speed crossovers that will have those replaced with #20s, but that's about the most speed-up that will happen.
Dan
canarob
Senior Member
Stouffville is already adding two more stops at Finch and East Harbour, so if stops at Scarborough and Danforth are also added, that's four more stops which would negate a lot of the acceleration/deceleration and frequency advantages of expansion and electrification in terms of trip times for most riders. Stouffville really needs express service from Unionville that only stops at Kennedy and East Harbour to shorten trip times as much as possible for core ridership.
Bojaxs
Active Member
Can you elaborate on this? What's a "speed turnout" and what's a "#20"?
How much of a speed increase will the #20's offer over the existing crossovers?
Northern Light
Superstar
I will leave the speeds on existing turnouts to others........
But a #20 generally permits a speed of up to 45mph in the cross over ~72km/ph. * there are factors that cause this to vary.
Here's list of some North American turnouts and their speeds:
Here's the more complicated math, which I will leave others to explain:
The above is from : https://hsr.ca.gov/wp-content/uploads/docs/programs/eir_memos/Proj_Guidelines_TM2_1_3R00.pdf
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