Quote:
Originally Posted by sim
Well that's assuming you have the same amount of stations in a tunnel and that currently the traffic lights never come into play, which they do. Not too mention the fact that you can likely run faster speeds when not having to drive-by-sight and the fact that you are removing a lot of the variability in headways that the transit mall (along with other surface crossings) invariably create. Finally, were it to go that far, extentions to 5 car consists also become a possibility in a tunnel; won't be interfering with any N-S streets (of course posing susbstantial costs to extend all platforms again).
~1 min headways (in the interlined portion) are not out of the realm of possibility.
Finally, it can be assumed that at least some of the current demand on the South - North Red line will be diverted to the hopefully built-out NC-SE Green line.
In short, I'm not convinced that those same problems will occur before a measurable increase in capacity has again become overwhelmed.
Agreed on the expense. I meant it depends on whether the NE-W would then also be tunneled or just left as is.
You may well know these patterns better than I, but I would be interested to see an OD matrix nevertheless. I'd also be wary of predicating future ridership patterns on current ones after a pretty fundamental change in infrastructure occurs. Again, not too mention that it also sets up the entire system for more easy and attractive transfers once a green line is implemented, provides for a more integrated network overall and allows for more operational flexibility.
Not to say that it's the best and only solution, but I think it's been prematurely discounted without the proper understandings of the potential benefits it may bring and without looking at the system more broadly and over the longer term.
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Seriously? Where are trains operated by humans, with cab control, on one minute headways? And exactly how fast do you think a train is going to run between two stations three blocks apart? You could have 200 km/h speed operations, it would take the same amount of time, since it's spent almost entirely accelerating and decelerating. And our downtown blocks are 150m; six car consists would be a problem but five are fine. (Four was not possible at 3rd St E, but that's no longer an issue.)
Interlining does reduce capacity (in addition to the obvious reduction by sharing one set of tracks between two lines). I'll use the City Hall interlocking as an example. If only trains to/from the NE were using the tracks, they could follow one another about as closely as possible given safe operating practise with inbound trains and outbound trains not interfering with each other. With the interlining, a train heading outbound to the NE blocks an inbound train from the S, and vice-versa.
Transfers would generally not be made more convenient by putting trains into a tunnel, since the dozens of bus routes that also go downtown are all at surface level. The only transfer that would be made more convenient by moving the Red line (NE-W) into the same tunnel as the Blue (NW-S) would be the transfer between the lines. Every other transfer to the Red line would be made more difficult, as there is now flights of stairs in the way. And the SELRT may reduce demand on the S line a little, but the future investment in transitways (the north transitway connects NE-NW and the south connects W-S) will reduce the demand for train-to-train transfers in the downtown.
I just don't understand why we would either choose to put ourselves at the same risk of an overcapacity line by interlining, or to spend an extra billion dollars we don't have on a second tunnel, just to make most transfers more difficult. Other than checking a box on some railfan scorecard. I'm also not sure why anybody disregards costs when talking practically about infrastructure; why don't we disregard gravity instead, it's about as realistic and a lot more fun.
The traffic lights aren't perfect, but we don't lose a lot of time due to them. And putting trains in a tunnel adds travel time to everyone who gets off them, which is most people. Obviously we need to put a line in a subway due to congestion, but it's not a great boon.
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