For this part, I'm using
"32 TPH" loosely as
"maximum capacity". That could mean 4 bullets for Green Line-like LRT, or 3-min headways for HRT
(ala Red Line Transformation). Likewise,
"16 TPH" means a line that can get by with
"half capacity", or more generally, a line that doesn't require squeezing all available capacity out of it.
Keep in mind, "16 TPH" is still very usable for connections that are less popular
(not anybody's lifeline) but still valuable. That's every 3.75 min for LRT, or every 6 min for HRT.
Now, my best guesses at where
"32 TPH" is needed:
- LMA - Ruggles - Nubian
- LMA-Ruggles would be the primary means for OL South and Northeast Corridor riders to LMA
- While Ruggles-Nubian is debatable in itself, LMA-Nubian will likely draw high demand from Roxbury/Dorchester riders, which will be merged with LMA-Ruggles. If an "extra 16 TPH" from the north needs to terminate somewhere, doing it at Nubian sounds better than Ruggles.
- Cambridge - LMA
- Can be split with 16 TPH to Harvard and 16 TPH to Kendall
- However, it's possible that Kendall-LMA may warrant 32 TPH if there are really so many Allston/Brighton/Brookline residents working in Kendall; likewise for Harvard to a smaller degree (?)
- Sullivan - Kendall
- Urban Ring has insane advantage here -- any halfway reasonable alignment brings huge time savings compared to a Park/DTX transfer
- I'd guess the demand for Harvard from the north is lower (unlike Harvard-Allston)
I argue that everything else is fine with
"16 TPH": nowhere near useless, just not with insane demand. In particular:
- Old Colony - LMA
- Decent distance advantage over a South Station transfer
- I'm not sure if demand from RL South and Old Colony lines is sufficient
- If you can somehow force Fairmount Line riders to take this route, that would change the calculus a lot; but I'd expect them to continue to prefer Nubian, due to bus connections
- Nubian - Old Colony - Seaport
- I've never been truly convinced about its need: Does Seaport have that strong of a draw?
- Also not the most geographically advantageous: Radial lines here already point NE-SW, so a route via South Station / Bay Village is almost as short
- Seaport's demand in this quadrant probably stops at Nubian: anyone from Ruggles is better off
- Airport (BL & Terminals) - Seaport - Old Colony - Nubian
- For Airport cross-harbor service, I continue to prefer sending them to BBY-South Station-Courthouse, rather than Nubian-Old Colony-Southie
- Factors against Nubian-Seaport above are still at play here: geography (ease of transfer near South Station) & influence stopping at Nubian
- In addition, depending on where the Seaport station is, the ring would probably miss out where most action is at
- Airport - Sullivan
- Heavily depends on alignment
- Going via Charlestown truly lives up Urban Ring's expectations, but even then, I don't think either Sullivan or Airport have insanely strong draws
- Going via Everett-Chelsea makes it a radial wannabe
- Sullivan - Harvard
- Mentioned above; it might even be that most demand comes from intra-Camberville
- Note that a Harvard-Sullivan-Charlestown-Airport line would bring Airport's influence all the way to Harvard; but even then, I don't think Airport is such a strong node
The 32 TPH segments had direct influences on this map. In particular:
- The strongest segment, Nubian-LMA-Cambridge, is served by overlapping Cyan and Lime lines (16 TPH each)
- Sullivan-Kendall is the only one not satisfied by the "ring system" alone -- but conveniently, our Kendall-BBY subway fills the gap
- This also helps with Allston/Brighton/Brookline - Kendall, to some extent
- The cross-harbor tunnel -- where quad-tracking is virtually impossible -- is split between the downtown/BBY oriented Magenta and the more "picture perfect" Cyan ring
- Everything else is fine with 16 TPH (Cyan alone), mostly for filling new connections
With all that said... If we do want the full "32 TPH" on everything, or "64 TPH" for Cambridge-LMA-Nubian, there's always the $$ option to build two ROWs through LMA.
