kEiThZ
Superstar
It would be nice to have some more spacious stations. Montreal seems to do quite well at this. What do they do that's different? Is it just a matter of cost?
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- Thread starter wyliepoon
- Start date
nfitz
Superstar
No. Not one subway line matches the SRT. And there are dwell times for that as well. I'm not saying that it's much faster; but it isn't slower, which is what some here try and pretend.
The technology is clearly not suited to the Toronto climate; but let's trash it for the right reason!
I disagree. Not only does the SRT have a dwell time, but given the reports of how overloaded it is in rush hour, it's more strained as a subway train at peak.
These things were designed to be smaller, lighter, with faster acceleration; why would one not assume that it would be faster?
golodhendil
Active Member
And you conveniently ignored the most important part of the logic, which is the longer station spacing and larger number of stations.
Let's do a simple gedankenexperiment:
Suppose line A has 12 stations 5 d-units apart, and line B has 4 stations 10 d-units apart (a generous assumption, since the majority of YUS and BD stations are more than twice as close as most SRT stations, and they have more than three times the number of stations as the latter).
Then suppose line A trains run twice as fast as line B (say, 10 d-unit/t-unit vs 5 d-unit/t-unit), and give it the benefit of the doubt that line B has the same dwell time as line A (say, 3 t-units).
Make the simplifying assumption that the trains run start-stop (no time for acc/dec) so the trains run at constant, highest speed between stations, which favours in the calculations whichever train has the higher acc/dec.
Doing the math, line A takes 0.5 t-units to go from station to station, while line B takes 2 t-units.
The total time for line A is 41 t-units, over a distance of 50 d-units, giving an average speed of 1.22 d-units/t-units.
The total time for line B is 18 t-units, over a distance of 30 d-units, giving an average speed of 1.67 d-units/t-units.
Thus, a line that runs faster trains (line A) has a slower average speed than a line that runs slower trains (line B), simply by virtue of longer station spacing and more stations.
And in real life, the subways are less than twice as fast as the SRT, the stations are even closer and there are even more stations than in this scenario, so the average speeds are even more skewed.
Acceleration has nothing to with speed. And saying that the trains are designed to be smaller and lighter would automatically imply higher speed, is like saying streetcars and peoplemovers, being designed to be lighter and smaller, should have higher speed than the TGV or shinkensen because the latter are bigger and heavier. Those are simply different and unrelated design criteria, and one does not imply the other.
Anyway, until we have real data about the operating speed of the two trains, this is the best and most logical we can do. My point is not that the SRT is "worse" in any way, I actually like the ART technology, and if not for network connectivity considerations I would favour keeping the ART in some form (that's O/T). All I was trying to say, is that LRT is slower and more importantly has smaller momentum than HRT in general and thus has less of a need for PSDs.
wyliepoon
Senior Member
Platform screen doors!
joeclark
New Member
Arial! Argh!
Wyliepoon, please stop using Arial. In the TTC setting it’s levels of fake.
Wyliepoon, please stop using Arial. In the TTC setting it’s levels of fake.
nfitz
Superstar
If the stations were infinitely spaced perhaps - but to suggest that the average speed in the subway has nothing to do with the acceleration only indicates that you flunked Newtonian mechanics!
And here's proof. If the acceleration of the train out of the station is reduced from 1 m/s² to 0 m/s², does the speed of the train change.
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Whoaccio
Senior Member
I wonder if it would be possible with PSDs to install a video projector on the track side of the screens, which could project commercials onto the screens. As the train would pull up, the projection would be interrupted and you would see the train.
Seems like something they would have "in the future." The future or Minority Report, whichever comes first.
Seems like something they would have "in the future." The future or Minority Report, whichever comes first.
golodhendil
Active Member
I almost thought you were making a joke, but seems like you misunderstood me (and things in general), purposely or otherwise.
"Acceleration has nothing to [do] with speed" was referring to your assertion that trains (or anything) being designed to have better acc automatically implies they are designed to operate at higher speed, which is false. But to entertain your "proof", obviously something that accelerates at 2 m/s^2 is going to reach the same speed faster than something accelerating at 1 m/s^2 (1 vs 0 is a meaningless comparison, since the latter train would not be moving out of the station at all), but precisely because of this, a faster-accelerating train would take less time than otherwise, further biasing the average speed to appear higher than a slower-accelerating train which takes longer to reach the same speed. (actually, if you meant a train changes from accelerating at 1 to 0, then the answer is no, the train's speed doesn't change anymore except slowly decreasing due to friction, but I don't think this is what you meant)
I might have chosen to pursue another science than physics, but I think I am sufficiently confident with basic concepts like those. Anyway, since there seems to be nothing constructive coming out of this discussion anymore, I think we should hand this thread back to Wylie for his wonderful renderings.
golodhendil
Active Member
nfitz
Superstar
When a train spends much of the journey time between two stations accelerating or deccelerating, then clearly the average speed is going to be a function of of the acceleration. The top design speed is irrelevent; an ALRV can in theory operate at 80 km/hr - yet never is.
golodhendil
Active Member
EXACTLY. A TRAIN THAT ACCELERATES/DECELERATES FASTER (PERHAPS THE ART) CAN THUS SKEW THE AVERAGE SPEED EVEN MORE TOWARDS APPEARING FASTER THAN A SLOWER-ACCELERATING TRAIN (LIKE AN HRT SUBWAY). (for like, the third time)
btw I was never talking about the top speed, but the speed they operate at; there's a difference (perhaps the phrase "designed to operate" threw you off). So, to reiterate: acc, top speed and operating speed have nothing to do with each other, average speed is affected by the first and third of those things (in ways that may not be immediately intuitive), and operating speed is different from average speed.
and btw the word is deCelerate, single "c"
I think I am done talking through a selective filter. kthxbye
nfitz
Superstar
Which why using the current SRT technology will yield a faster service than using the current subway technology - as long as there is no snow!
Railization
Active Member
Sorry to spoil the party, but there is something to think about regarding the average speed discussion.
One of the advantages of ATO/ATC is that it allows faster average speeds by about 10%. However, this has nothing to do with higher maximum speeds, which as pretty much set in stone by elements such as track curvature and slopes.
How do they get that 10% average speed increase? It is coming from "high rate" service as they call it. This involves faster acceleration.
Now, 10% is fairly optimistic, even though that only translates into a 3km/h faster average. I know that Steve Munro is extremely skeptical about that 10% increase. There's a good reason to be skeptical, too, since there are other factors that can keep the train speeds at a slower average, and include things like passenger crowding and weather, among other things.
One of the advantages of ATO/ATC is that it allows faster average speeds by about 10%. However, this has nothing to do with higher maximum speeds, which as pretty much set in stone by elements such as track curvature and slopes.
How do they get that 10% average speed increase? It is coming from "high rate" service as they call it. This involves faster acceleration.
Now, 10% is fairly optimistic, even though that only translates into a 3km/h faster average. I know that Steve Munro is extremely skeptical about that 10% increase. There's a good reason to be skeptical, too, since there are other factors that can keep the train speeds at a slower average, and include things like passenger crowding and weather, among other things.
syn
Senior Member
Wow, great work Wylie. There are only a few things I would change. I would use a different set of floor tiles, without the smaller green diamond tiles at each corner. In combination with the blue tiles it all kind of looks like some sort of kitchen.
I'd also put something on the walls instead of leaving them bare concrete. I think minimalism would work well with these station designs, as opposed to imitating the look of the aesthetically questionable Sheppard line.
Overall though you did an excellent job.
I'd also put something on the walls instead of leaving them bare concrete. I think minimalism would work well with these station designs, as opposed to imitating the look of the aesthetically questionable Sheppard line.
Overall though you did an excellent job.
golodhendil
Active Member
That I don't disagree with, when we are talking from a service/average speed perspective. Glad we're agreeing on somethingWhich why using the current SRT technology will yield a faster service than using the current subway technology - as long as there is no snow!
Though I guess, assuming the crowding and weather situation doesn't differ significantly between having or not having the ATO/ATC, faster acceleration etc could still produce a significant net increase in average speed (don't know about the 10% figure, of course)