Green Line Reconfiguration

Brattle Loop

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Can someone smarter than me explain the pitfalls of putting a single track surface line up Linwood Street and turning onto the SB track to Lechmere using Poplar street? Could eminent domain make the curve less tight?
From where to where? Linwood's on the entire wrong side to access the southbound/Lechmere Union Square branch track, which is (annoyingly) already on an incline at that position, meaning you'd need to climb over it (and it's unclear to me whether there's sufficient clearance over the Fitchburg Line to merge into the southbound track on that incline). Or did you mean connecting to the southbound track of the Medford branch? In that case, it'd be impossible to have a surface connection there without severing the community path (much outrage would follow), not that it's clear what purpose that would solve, given that you'd still have to get across the Fitchburg main from the Grand Junction, and if you're already digging there it'd probably make more sense to find out if its possible to make the grades work to hit an incline from the Union Square branch rather than invite all that street running. That said, the area where Poplar meets the Medford Branch ROW looks like it might be wide enough to snake in a descending incline from an elevated LRT spur from the Sullivan direction to get to Lechmere.
 

Riverside

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Can someone smarter than me explain the pitfalls of putting a single track surface line up Linwood Street and turning onto the SB track to Lechmere using Poplar street? Could eminent domain make the curve less tight?
It's an interesting idea -- I assume you mean in order to solve the Sullivan to Lechmere problem that I was diagramming?

Like this, right?

1667948544078.png


It reminds me a little bit of the idea I sketched out back in June of using New Washington St similarly:

1667948621767.png


There are probably three problems with going via Poplar St:
  1. Those curves are manageable but speed-killing; this will aggravate problem 2
  2. It's a long diversion; going northbound, the Lechmere > Sullivan route via the yard lead would take about 1,000 feet, while it takes this route over 5,000 feet (i.e. a mile) to go an equivalent distance; beyond the increase in travel time to an already circuitous route from Chelsea to downtown, this kind of mismatch also makes scheduling and dispatching more of a challenge
  3. The killer, as @Brattle Loop rightly points out, is the impact to the community path (in blue on my diagram); in theory that could be addressed by elevating either the track or the path, but that opens up its own can of worms
My conclusion is that there are a number of imperfect ways to create a Lechmere <> Sullivan LRT connection, each with their own drawbacks. I don't see a way to do a "perfect" connection that doesn't involve either tunneling, super high elevated tracks, or a rebuild of Brickbottom Junction altogether. Combined with my skepticism about the fundamental usefulness of such a connection for standard revenue service, those challenges lead me to consider Lechmere <> Sullivan "out of scope" for a first generation Green Line Reconfiguration project. (Particularly since connecting the Grand Junction itself is going to also be a challenge, but by contrast one with very clear benefits and worth -- I'd rather spend the political and financial capital there instead.)
 

Brattle Loop

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My conclusion is that there are a number of imperfect ways to create a Lechmere <> Sullivan LRT connection, each with their own drawbacks. I don't see a way to do a "perfect" connection that doesn't involve either tunneling, super high elevated tracks, or a rebuild of Brickbottom Junction altogether. Combined with my skepticism about the fundamental usefulness of such a connection for standard revenue service, those challenges lead me to consider Lechmere <> Sullivan "out of scope" for a first generation Green Line Reconfiguration project. (Particularly since connecting the Grand Junction itself is going to also be a challenge, but by contrast one with very clear benefits and worth -- I'd rather spend the political and financial capital there instead.)
Agreed on the prioritization, and thank you for that New Washington Street diagram. I was trying to envision a path up there but it's always helpful to have a visual aid.
 

Riverside

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On the topic of colors, since playing with them is indeed fun, I'd probably chuck the emerald in the bin (or maybe keep it but not use it as an official reference)
Yeah, this is what I'm leaning toward at the moment. Even if it's all still called the "Green Line", I think having the A, B, C, D, E, F, G, and R all be one color on the map is both too overwhelming visually and too confusing -- in particular if we are serious about the Kenmore Division all short-turning in downtown. It would magnify the existing problem of standing on the inbound platform at Science Park and waiting for a Cleveland Circle train to come, which the T has finally managed in the last couple of years to sorta meaningfully indicate on maps, but which is simplified by using a separate color (even if it's still just called the "Green Line").
The Aqua line is fine (though I'd call it Turquoise or Cyan if it were operationalized, because otherwise a bunch of tourists are going to get lost trying to find the Aquarium), but only so long as that BRT service isn't that teal color because it's way too similar.
Honestly I haven't loved the name "Aqua" since it replaced "Teal" (because, again, "Teal Line" sounds too much like "T line") -- I don't find it particularly euphonic, and it somehow feels aesthetically dated. (Also it would create debate whether it's AH-kwa, AW-kwa, or AK-wa -- /a/ vs /ɑ/ vs /æ/ for my fellow IPA nerds.) But also yeah the "Aqua-rium" problem is real.

Maybe I'll swipe @The EGE's idea and call this one the Magenta Line -- we'll say it's because it's the connection between Harvard (crimson red) and the Seaport (ocean blue)! (And in fact, it connects Harvard times three -- the Cambridge campus, the Stadium/Business School in Allston, and their hospitals in Longwood; I'm so tempted to just call it the Crimson Line but even I have to admit that it's too similar to differentiate, womp womp.)
I'd personally turn that into the gold line (give the shiny-metal colors to the BRT stuff, plus at least it wouldn't be making a real transit line a similar color to the buses, and pick something else for that J service. (Brown and pink are readily available, while one of magenta or violet, as well as indigo, could be doable if the CR was kept to a single standard - the equipment and some of the signage has a tendency to look a lot pinker than the digital versions.)
Yeah I mean this is where colors start to get difficult:
  • Yellow is hard to read on a map (hence my preference for Gold) and in some situations can be regrettably racialized
  • Brown has racial and identity meanings. I'd love to hear an oral history about Chicago's naming exercise in the early 90s because obviously they have a Brown Line there, but I have a hard time imagining it being used here
    • If we "needed" to use a brown color for a line, we have some alternatives -- copper and bronze, for example (although both of those obviously have connotations of their own -- bronze as "third place" for example behind gold and silver), or something botanical like "chestnut"
    • We also could take a page from Los Angeles' book (prior to their ongoing switch to letters) and have a system that's mostly colors but with one random exception (in their case, the Expo Line)
  • Black and White obviously are overwhelmingly racialized, and to boot are difficult to map (black in part because of its overlap with labels and typical methods to indicate transfers)
  • Pink... I'd argue that Pink doesn't necessarily have a single overwhelming connotation like brown or black, but has a number of different connotations, at least one of which will be seen as strong/obvious by different segments of the population (e.g. some folks will see association with gay identity, others will recognize it as the most overwhelmingly gendered color and/or associate it with breast cancer awareness)
    • (To me, lavender faces similar challenges, though less extremely so)
    • If you "need" a pink color for a line, one could use Rose, as I've proposed elsewhere
  • Magenta, Purple, Violet, Indigo -- as you mention, you can use two or maybe three of these, but not all four
    • My vote in Boston is for Magenta, Purple (applied to some sort of mainline service) and Indigo
Now, I can hear someone reading the above and saying, "Well, Riverside, if we really want to, we could find controversial meaning in the current colors too -- blue is gendered, red is racialized, and blue, red and green all have political meanings." Which is a fair point. In response, I'd point to this handy graphic that Ari Ofsevit created:



Blue, red, and green are overwhelmingly among the most common colors for rapid transit services. This normalization means that they have strong associations as "rapid transit colors" to begin with, which can offset those other connotations; pink and brown lack those associations, and so their other connotations come much more readily to mind.

I think LA's example is instructive. They started with a simple Blue and then Red and then Green in the early 90s, and then...
  • added a Gold in 2003,
  • an Orange in 2005,
  • a Purple in 2006,
  • a Silver in 2009,
  • followed by the "Expo" (light blue) in 2012
before beginning a shift toward letter names in 2020 -- not coincidentally, I'd argue, around the same time that the K Line was coming into focus, which was going to be colored pink on the map. (Since, yes, they had run out of other colors!)

Which is to say, if your system is going to have more than 8 named routes, colors probably are approaching the limits of their usefulness. And here on ArchBoston we usually talk about...
  1. A Washington Street Subway line
  2. A line over the Charles River
  3. A line to East Boston
  4. A line under Boylston St
  5. A line under Huntington Ave
  6. A line to the Seaport
  7. A line on the Fairmount Line
  8. A circumferential line or two
which puts us right on the transition point that LA has already reached.

tl;dr: Colors are fun and also hard and have limits to their usefulness.
 

Brattle Loop

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Honestly I haven't loved the name "Aqua" since it replaced "Teal" (because, again, "Teal Line" sounds too much like "T line") -- I don't find it particularly euphonic, and it somehow feels aesthetically dated. (Also it would create debate whether it's AH-kwa, AW-kwa, or AK-wa -- /a/ vs /ɑ/ vs /æ/ for my fellow IPA nerds.) But also yeah the "Aqua-rium" problem is real.

Maybe I'll swipe @The EGE's idea and call this one the Magenta Line -- we'll say it's because it's the connection between Harvard (crimson red) and the Seaport (ocean blue)! (And in fact, it connects Harvard times three -- the Cambridge campus, the Stadium/Business School in Allston, and their hospitals in Longwood; I'm so tempted to just call it the Crimson Line but even I have to admit that it's too similar to differentiate, womp womp.)
Dump the teal/turquoise, go to that other 90s standard, Eggplant. (That would at least be a hilarious name for a line. Have both and it would look like everything Disney did in the mid-90s...or the Anaheim Ducks before they dropped "Mighty".)

  • Yellow is hard to read on a map (hence my preference for Gold) and in some situations can be regrettably racialized
  • Brown has racial and identitymeanings. I'd love to hear an oral history about Chicago's naming exercise in the early 90s because obviously they have a Brown Line there, but I have a hard time imagining it being used here
    • If we "needed" to use a brown color for a line, we have some alternatives -- copper and bronze, for example (although both of those obviously have connotations of their own -- bronze as "third place" for example behind gold and silver), or something botanical like "chestnut"
The CTA's naming largely, though not exclusively, adopted colors that had been used for the lines prior to their being official designated with colors. At the time, for instance, the Ravenswood line was depicted in brown (though black and purple had apparently been used in previous times)...so they just called it the Brown Line. I can both understand why some people might see racialized elements if the T were to adopt certain colors, and simultaneously find it somewhat annoying that there's so frequently no presumption of neutrality (slash innocence) in too many contexts these days. (There's only so many colors that are sufficiently-distinguishable from each other.)

Blue, red, and green are overwhelmingly among the most common colors for rapid transit services. This normalization means that they have strong associations as "rapid transit colors" to begin with, which can offset those other connotations; pink and brown lack those associations, and so their other connotations come much more readily to mind.
Also worth pointing out that it's a choice for an agency whether to care about what some people will think. It's at least a logically-coherent argument for an agency to say "it's just a color, you don't need to read deeper meaning into it" on the basis that, as noted, there aren't that many to choose from (i.e. copper and bronze may have issues distinguishing them from orange, which is a no-no in wayfinding) and simply ignore anyone who complains. (Note to any agency managers intending to try this approach: it would be good if you anticipate these types of criticism up-front rather than get caught looking like you didn't realize people might complain.)
 

Riverside

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[concerns about mixing the A with the G & Q]

Yes, this was something I had mixed feelings about. The Q also becomes somewhat problematic in that it intermingles with the "heavy metro" D/E as well as the "light metro" J, which also is less ideal (though I also gave up the ghost on perfect separation there by having the G and J mix on the Grand Junction).

...

The A doesn't need to go to West Station, though. It could just follow the 57's route. West Station will have connections to Back Bay via the Q, and downtown via the G (plus via Regional Rail). And... ultimately what I want is to extend the Blue Line to West Station, which would eliminate the need for the A to West Station altogether. That's a much larger capital expense, though, and while I want the Commonwealth Subway future-proofed to support HRT tracks as well (hence the dashed line), I don't want to make it a prerequisite.

[concerns about frequencies on services with lots of grade crossings]

This is really useful feedback. (And provides an occasion to remark that I try always to be mindful in discussion with you and others that, like, this is your frickin' job, whereas it is decidedly not something I have any training or professional experience in.)

The J -- for what it's worth -- I think could be broken up into shorter segments to mitigate some of your concerns. I also don't know that the J needs to run all the way to Nubian -- although I think Nubian-Ruggles-Longwood is going to be inundated with buses such that there will need to be dedicated transit infrastructure anyway.

I should also point out that I left the Q's frequency somewhat undefined -- anywhere from 6 tph to 15 tph. Some of that was dependent on how high we could push the frequency through the Longwood Transitway.

I don't love it, but we could reimagine this corner of the map more simply:

[insert map: J to West Station, Q runs on its own through Longwood Transitway, and maybe adds a branch to Brigham Circle?, A runs via Packards Corner -- I need to turn in soon, so I'll post a map of this later!]

This could reduce the frequency requirements through Longwood while still maintaining increased connectivity across the system.
As promised, an updated map:

Grand Mini Map - Simplifying v2 alt.png


Mostly simplifications, but some additional tweaks:
  • A is rerouted from West Station to avoid mixing Kenmore Division and Bay Village Division services
    • Future-proofing for a Blue extension to Boston University and West Station is indicated more specifically
  • J is cut back to Boston University, with potential provisions for extension south depending on reliability
    • It sounds like the signal prioritization vs frequency battle you are describing (@The EGE) is somewhat of a political rather than engineering battle, yes? If so, I would opt for a phased approach: start with a lower frequency service (as seen here), build public support for the corridor, and eventually increase frequencies as the service gains more clout
  • Q is changed to Magenta Line (as discussed above)
  • Magenta Line is split into two services:
    • Q: Harvard to Eastport (name TBD, but it's Silver Line Way)
    • S: Brigham Circle to Design Center
    • More on this below
  • Silver Line rerouted to handle LMA-Nubian service and eliminate branching
  • Other minor changes include dotted extensions at north end of D, elimination of the McGrath Hwy transfer station, and relocation of Union Sq Somerville to its correct location
Splitting the Magenta Line is something I'm toying with. The question isn't really per se whether it's better to provide a Brigham Circle-Seaport OSR specifically, but rather whether the line as a whole can be viable even if not all trains run through the Longwood Transitway. Splitting some trains off to Brigham Circle has some unique potential: because of the particular overlap of services here, and because Brigham Circle, Longwood Medical Area, and Louis Pasteur stations would all have overlapping walksheds, this might be a scenario where the S service could have lower frequencies than would normally be acceptable.

For example, if the Magenta Line gets 15 tph on its core, but we wanted the Q to have better-than-8-minute headways between Harvard and LMA, we could do a 2:1 split: 10 tph (6 min) to the Q and 5 tph (12 min) to the S. Yes, that is a long time to wait for an S at Brigham Circle, but you'll likewise have the choice of a D or E coming every 4 minutes, and the ability to transfer to a higher frequency combined Magenta Line service further down the line at Back Bay. Coming from the other direction, if you are going from South Station to Longwood, there's a good chance you could walk from either Louis Pasteur or LMA, meaning you can take either a Q or S.

(Yes, Design Center gets a bit hosed with 12 min headways, so you can play around with this as you like.)

The point is that there is a reasonable "relief valve" to provide maximum headways on a Seaport service in the tunneled section, but have a way to slightly reduce frequencies on the surface section if needed, while still providing a usable service. (And it's not like it would be a bad thing to have a Brigham Circle-Seaport OSR either.) Alternatively, as discussed above, the turnback at South Station would give you a way to boost frequencies in the Seaport if needed while keeping frequencies on the rest of the line more modest (although I'd argue that South Station-Back Bay-Huntington is likely to see as much demand as South Station-Seaport).

Overall, the changes in this version of the map are meant to reduce interlining between services of differing characters (e.g. A vs Q & J), and "reserve" the grade-crossing-heavy segments for the services that can have the most impact due to their position in the system overall. This design subjects the Longwood Transitway to frequencies potentially as modest as today's Green Line branches, and decouples the frequency requirements of the LMA-Nubian segment (now shouldered by SL1) from the requirements of the Grand Junction and Chelsea.

(Not shown on the map: the SL1 bus lanes in the LMA-Nubian segment would probably also serve extensions of the current Dorchester bus network; keeping the Gold out of that stretch frees up more slots for those busses, which probably is higher impact.)

Brief note on Allston: the alignment here is meant to be handwavy/agnostic. As I understand it, there's still open question about exactly what the street layout etc will be in this area once Harvard finishes with it. My hope would be that LRT provisions could be included in those designs, minimizing the impact of higher-frequency service at grade crossings as much as possible. (Ideally, you'd have a short subway, as I think F-Line outlined way back upthread, but as I say, I'm trying to be agnostic.)

~~~

Also. Crazy transit pitch incoming. If you are able to convince the Powers That Be to support increased frequencies through the Longwood Transitway, you could -- probably not should -- but you could run an LRT service from the Kenmore Loop out the Fenway portal, cut across this parking lot, join the Longwood Transitway + Forsyth St transit mall, and zig-zag from Ruggles to Nubian. At 2.5 miles one-way, you can keep dispatching taut as you have cars pinging back and forth. The downside is that you introduce greater variability into the Magenta Line's ecosystem, which might disrupt reliability. And again, as alluded to above, this might be a scenario where BRT's ability to absorb non-BRT feeder routes is more desirable than the capacity increases available via LRT (i.e. instead of a closed Kenmore-Nubian LRT line, you have an open network with a Kenmore-Nubian BRT trunk and feeder branches extending directly out to Nubian, Egleston, Mattapan, Ashmont, etc). Whether the BRT also uses the Longwood Transitway (which again might introduce reliability issues), or uses another route through Longwood (TBD), is another open question.
 

Riverside

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(i.e. copper and bronze may have issues distinguishing them from orange, which is a no-no in wayfinding)
There are larger points you've made that I'll try to respond to tomorrow, but did want to clarify that what I'm proposing here is a "Copper Line" or a "Bronze Line" that basically just uses a brown-colored line on a map -- brown enough to be distinguished from Orange, but just called "Copper" or "Bronze" instead of "Brown".
 

Brattle Loop

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There are larger points you've made that I'll try to respond to tomorrow, but did want to clarify that what I'm proposing here is a "Copper Line" or a "Bronze Line" that basically just uses a brown-colored line on a map -- brown enough to be distinguished from Orange, but just called "Copper" or "Bronze" instead of "Brown".
I'll likely edit this to add comments on the larger post, but I wanted to acknowledge that I didn't get that's what the intention was. That'd be a good solution to avoid any unnecessary criticism (I'd go with bronze on account of it being a.) closer to brown than orange and b.) sounding better to me than copper, which doesn't quite roll off the tongue as nicely).

EDIT: As promised, more comments.

  • J is cut back to Boston University, with potential provisions for extension south depending on reliability
    • It sounds like the signal prioritization vs frequency battle you are describing (@The EGE) is somewhat of a political rather than engineering battle, yes? If so, I would opt for a phased approach: start with a lower frequency service (as seen here), build public support for the corridor, and eventually increase frequencies as the service gains more clout
Is that tied into the Commonwealth line, or separated? If we're terminating the J at BU, it might be useful to have the ability for the trains to run to Kenmore. Probably not as a regular service pattern, but it might help dealing with, say, crowds from Sox games and such.

  • Q is changed to Magenta Line (as discussed above)
Probably down to the map, and likely manageable (or else we'd have to reshuffle the colors...again), but in that image there's way too much similarity between magenta and red. If that were real-world some poor sods trying to go from Harvard to the Common would wind up at the cruise terminal. I suppose we could just put up signs that said "THIS ONE DOESN"T GO TO PARK STREET" kind of like those signs screaming at people to take anything but an "E" to get to Fenway on the GL.

For example, if the Magenta Line gets 15 tph on its core, but we wanted the Q to have better-than-8-minute headways between Harvard and LMA, we could do a 2:1 split: 10 tph (6 min) to the Q and 5 tph (12 min) to the S. Yes, that is a long time to wait for an S at Brigham Circle, but you'll likewise have the choice of a D or E coming every 4 minutes, and the ability to transfer to a higher frequency combined Magenta Line service further down the line at Back Bay. Coming from the other direction, if you are going from South Station to Longwood, there's a good chance you could walk from either Louis Pasteur or LMA, meaning you can take either a Q or S.

(Yes, Design Center gets a bit hosed with 12 min headways, so you can play around with this as you like.)
I like this idea. Any chance a Silver Line branch could take up any of the slack if Design Center can't quite swing 12 minute headways? Even that Aqua/Teal (I'm just calling it the Sharks line in my head) stop is pretty close that it'd be useful for anyone who doesn't need a direct Magenta ride.


It's not immediately clear to me from the map, but would a Gold-Green transfer have to happen at the GJ? It'd be a hell of a lot easier to site the station for it, but at the cost of losing the greater Union/Medford frequencies if the transfer was at Brickbottom. Obviously if "getting downtown" was the primary objective, a transfer to Orange at Sullivan would be better, but some Green transfers would still need to be provisioned for. (Also, now I'm noticing that the Gold and Orange look quite similar on the map, which will be funny when someone boards at Sullivan trying to get to the Bruins game and winds up watching the Terriers.)
 
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WarpedReality

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There are probably three problems with going via Poplar St:
  1. Those curves are manageable but speed-killing; this will aggravate problem 2
  2. It's a long diversion; going northbound, the Lechmere > Sullivan route via the yard lead would take about 1,000 feet, while it takes this route over 5,000 feet (i.e. a mile) to go an equivalent distance; beyond the increase in travel time to an already circuitous route from Chelsea to downtown, this kind of mismatch also makes scheduling and dispatching more of a challenge
  3. The killer, as @Brattle Loop rightly points out, is the impact to the community path (in blue on my diagram); in theory that could be addressed by elevating either the track or the path, but that opens up its own can of worms
My conclusion is that there are a number of imperfect ways to create a Lechmere <> Sullivan LRT connection, each with their own drawbacks. I don't see a way to do a "perfect" connection that doesn't involve either tunneling, super high elevated tracks, or a rebuild of Brickbottom Junction altogether. Combined with my skepticism about the fundamental usefulness of such a connection for standard revenue service, those challenges lead me to consider Lechmere <> Sullivan "out of scope" for a first generation Green Line Reconfiguration project. (Particularly since connecting the Grand Junction itself is going to also be a challenge, but by contrast one with very clear benefits and worth -- I'd rather spend the political and financial capital there instead.)
Thanks! I wasn't perfectly clear the first time around, but you got the meaning of my question. Certainly, connecting Sullivan to Lechmere is too messy to be a 1st generation build, but when it comes to doing the 2nd generation stuff do you think problems #1 and #2 can be mitigated by taking some industrial land via eminent domain? How important is it to grade separate the community path from a single track LRT track?
 

Riverside

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Thanks! I wasn't perfectly clear the first time around, but you got the meaning of my question. Certainly, connecting Sullivan to Lechmere is too messy to be a 1st generation build, but when it comes to doing the 2nd generation stuff do you think problems #1 and #2 can be mitigated by taking some industrial land via eminent domain? How important is it to grade separate the community path from a single track LRT track?
Well, to be clear, I am an overenthusiastic amateur with no formal training, so what I think may be quite wrong. :)

Could eminent domain smooth out the curves and shorten the diversion distance? Hmmm, maybe a bit?

The tricky thing is that both the viaduct and the community path have an elevation change along here, as you can see on Google Maps looking southwest. So you either need to have a convergence well to the north of the "landing" or you need a convergence well to the south.

Three alternatives plotted below:

Alt 1 (pink): surface streets, no eminent domain

Alt 2 (purple) surface, eminent domain clears buildings, grade crossing with community path at ground level

Alt 3 (orange) mostly elevated, diverging on the viaduct itself, maintaining elevation while Medford branch tracks & community path drop, in order to clear over the community path as soon as it reaches ground level

1668016957604.png


Alts 2 and 3 definitely are better on the curves issue, and Alt 3 probably makes a noticeable difference in running time compared to Alt 1, but still is going to be a marked difference -- my rough estimate is that it only saves you about 700' of running track, so you're still looking at a 400% difference compared to running northbound.
How important is it to grade separate the community path from a single track LRT track?
Well, to a certain extent this will depend on whether the track is in regular revenue service. If it were used only during "special services", then maaaaaaaaybe you could possibly swing it? (Maybe particularly if it were a protected crossing with gates and everything.) But in every day revenue service, I think it'll be a non-starter. Too disruptive to path users, and likely enacting too severe a speed penalty on the trains (especially if the crossing isn't fully protected).

The other angle that we haven't talked about yet is train traffic. Looping around via the northwest quadrant means that the stretch of westbound track between the Sullivan/Lechmere divergence (between the viaduct and the community path in the lower right of the above image) and the divergence to Poplar St would see:
  • all westbound Union/Porter trains
  • all southbound Sullivan-Grand Junction trains
  • all westbound Lechmere-Grand Junction trains
  • all southbound Sullivan-Lechmere trains
Which pretty easily could become a bottleneck. To me that tips the scales in favor of doing something via New Washington St, which has a lot of the same drawbacks (including a similar running difference in northbound vs southbound), but which avoids the traffic.
I'll likely edit this to add comments on the larger post, but I wanted to acknowledge that I didn't get that's what the intention was. That'd be a good solution to avoid any unnecessary criticism (I'd go with bronze on account of it being a.) closer to brown than orange and b.) sounding better to me than copper, which doesn't quite roll off the tongue as nicely).
I myself am most intrigued by the sound of "the Chestnut Line", but I'm sure some market research would be revealing one way or another!
J is cut back to Boston University, with potential provisions for extension south depending on reliability

Is that tied into the Commonwealth line, or separated? If we're terminating the J at BU, it might be useful to have the ability for the trains to run to Kenmore. Probably not as a regular service pattern, but it might help dealing with, say, crowds from Sox games and such.
I haven't fully sketched out what I would do with this junction, so it's an open question. F-Line did a design a while back, but his did not connect to a surface running route on Park Dr, and connected the Commonwealth Subway itself, which I'm suggesting is actually not vital.

Assuming a Commonwealth Subway is built (which I do recommend), my thinking would be to keep the surface tracks in place between Blandford Portal and BU Bridge (convert the ROW to support BRT as well), and use them as a non-revenue connection for equipment moves and special services to Kenmore as you mention. (Alternatively, you could look at a connection at the Fenway portal via this parking lot, but I think the curve is too tight.)
Probably down to the map, and likely manageable (or else we'd have to reshuffle the colors...again), but in that image there's way too much similarity between magenta and red. If that were real-world some poor sods trying to go from Harvard to the Common would wind up at the cruise terminal. I suppose we could just put up signs that said "THIS ONE DOESN"T GO TO PARK STREET" kind of like those signs screaming at people to take anything but an "E" to get to Fenway on the GL.
Yeah, the colors are a pain, particularly on this map since I'm also competing with OpenStreetMap's color palette (ie. the yellows of major surface roads, the magentas of limited access highways, etc). This is also why the "Gold Line," as you mentioned, is a bit on the orange-ish side. I'm confident that we can find hues of these colors that are distinguishable on a diagram, but likewise believe letters are probably the better solution long-term.
I like this idea. Any chance a Silver Line branch could take up any of the slack if Design Center can't quite swing 12 minute headways? Even that Aqua/Teal (I'm just calling it the Sharks line in my head) stop is pretty close that it'd be useful for anyone who doesn't need a direct Magenta ride.
Yeah for sure, I think there are options to supplement Design Center: Silver Line, Navy Line (because it has so many water crossings and [could] serve the Navy Yard! 😛), and/or short-turn South Station-Design Center supplemental service.
It's not immediately clear to me from the map, but would a Gold-Green transfer have to happen at the GJ? It'd be a hell of a lot easier to site the station for it, but at the cost of losing the greater Union/Medford frequencies if the transfer was at Brickbottom. Obviously if "getting downtown" was the primary objective, a transfer to Orange at Sullivan would be better, but some Green transfers would still need to be provisioned for. (Also, now I'm noticing that the Gold and Orange look quite similar on the map, which will be funny when someone boards at Sullivan trying to get to the Bruins game and winds up watching the Terriers.)
You mean would it be possible to have a transfer station somewhere in this red circle? (To enable transfers between Gold and all three Green branches? Functionally equivalent to a transfer at Lechmere?)

1668019563862.png


I'm skeptical -- I think it's pretty likely that all of the grade changes would kill us here and make it difficult to site platforms on flat stretches that still are close enough to make for decent transfers.

This is the best I could come up with as a quick sketch:

1668020079944.png


The Gold Line line platform is a complete guess, but the idea is that whatever platforms it gets would have to be somewhere on that side of the junction -- whether an island platform or side platforms or whatever. Likewise, the southbound Green Line platform would need to be south of the Union-Medford merge, which means that it's at least 250' of walking between the platforms (plus a couple of grade changes).

So... maybe something could be done? But definitely a Project™ . (Also I'm looking now and the platforms I sketched above are way too short -- the Medford and Lechmere platforms could be extended, but the Union platform is very constrained.)

Like I mentioned previously, one way to offset would be to add a Sullivan Branch <> Union Branch Gold Line service, which should be very doable from a capacity perspective. Journeys between the Medford Branch and Sullivan Branch would still be inconvenient... I guess you could also leverage the yard leads going toward Medford, though that would probably end up using level crossings in the yard (and would make for a pretty useless U-shaped service).

This was one reason I was looking at a station at McGrath Highway. (I really need to start looking at that junction more carefully.) Looking back, F-Line definitely thought it was possible fit a small station on the Grand Junction there, though I understand why @The EGE is skeptical.

Maybe you do a Gold <> Union transfer at McGrath Hwy, and Gold <> Medford transfer at Brickbottom Junction. The viaduct for the Medford Branch is mostly level, so, maybe you could do it?

1668030936012.png
 

Brattle Loop

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I myself am most intrigued by the sound of "the Chestnut Line", but I'm sure some market research would be revealing one way or another!
If it had an Orange Line-style train self-immolation in December, the song jokes would write themselves...

Assuming a Commonwealth Subway is built (which I do recommend), my thinking would be to keep the surface tracks in place between Blandford Portal and BU Bridge (convert the ROW to support BRT as well), and use them as a non-revenue connection for equipment moves and special services to Kenmore as you mention.
That's a good idea. I hadn't thought about the prospect of burying the B (or the E for that matter) but keeping the reservations around for transit purposes, that makes a lot of sense.

The Gold Line line platform is a complete guess, but the idea is that whatever platforms it gets would have to be somewhere on that side of the junction -- whether an island platform or side platforms or whatever. Likewise, the southbound Green Line platform would need to be south of the Union-Medford merge, which means that it's at least 250' of walking between the platforms (plus a couple of grade changes).

So... maybe something could be done? But definitely a Project™ . (Also I'm looking now and the platforms I sketched above are way too short -- the Medford and Lechmere platforms could be extended, but the Union platform is very constrained.)
Makes sense. Sometimes we do have to concede to reality (this isn't the God Mode thread, after all) and we're lucky at least that the existing junction allows access in the Sullivan direction at all, so if a wonky transfer is what we have to deal with, so be it.

This was one reason I was looking at a station at McGrath Highway. (I really need to start looking at that junction more carefully.) Looking back, F-Line definitely thought it was possible fit a small station on the Grand Junction there, though I understand why @The EGE is skeptical.
So many thorny questions and potential problems right around there under the McGrath overpass, that'd be an area where we'd be white-knuckling it waiting to hear the results of the studies. I wouldn't be surprised if we had to settle for only one transfer from Gold; it seems like the GJ version F-Line suggested might be easier because there's somewhat more space there. Though, that would also depend on what kind of grades would be necessary (if it's even possible) to duck under the Fitchburg and then rocket back up to link up to the GLX tracks. A Gold-GJ Inbound to Lechmere-Medford double-transfer would be deeply annoying, but enough improvements to the buses off of the Union Square branch and Orange/Gold could probably mitigate the numbers needing that specific pair.
 

Riverside

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View attachment 30262

...

Frequencies could look something like this.
Green Line: every 6 min on each service
A Harvard - Park Street
B Boston College - Park Street
C Cleveland Circle - Park Street

Magenta Line: every 7.5 min on each service
D Riverside - Seaport
J Needham Junction - Porter
E Hyde Square - Mystic Valley Parkway
K Hyde Square - Seaport
F Nubian - LMA via Grand Junction
L Seaport - LMA via Grand Junction

Combined headways are 3 min (20 TPH) between Packards and Kenmore, 2 min (30 TPH) Kenmore to Park. 4 min (15 TPH) Newton Highlands to MFA, 4 min Hyde Square to MFA, 2 min MFA to Back Bay, 2 min Boylston to Lechmere. South Station to Seaport would have 22.5 TPH; you could probably add an additional South Station-Seaport shuttle if 30 TPH on even headways was desired.
Yeah, I just have to say again, on re-reading this, how much I like this vision, and irrationally how tickled I am at the convergence in our ideas.
I think I mentioned before -- the ~8 min takt is actually key here. In both of our systems, all key segments see "double frequency" services, usually composed of two branches which split somewhere around the Inner Belt. Because the system stretches out into the suburbs, our "single frequency" needs to be modest enough not to oversaturate the service, but high enough that there's still room to "double up" once you hit the Inner Belt. What's more, we then need to be able to "triple up" because in fact there are two trunks (Huntington and Washington), which you can do here: 7.5 tph > 15 tph > 30 tph.

A ~6 min takt maxes you out by the time you "triple up": 10 tph > 20 tph > 40 tph. A 10 min takt, on the other hand, leaves both your single and double frequency tiers a little on the low side, and gives you the lowest maximum triple frequency (since you can't "quadruple up" further): 6 tph > 12 tph > 24 tph.

The ~8 min takt sits in a sweet spot where both single frequency and double frequency tiers are reasonable transit (turn up and go), where frequencies can be combined to the third degree in dense areas, and where the cascade of "triple order" to "double order" to "single order" aligns well with the branching structure of the network on the southside.
That's a good idea. I hadn't thought about the prospect of burying the B (or the E for that matter) but keeping the reservations around for transit purposes, that makes a lot of sense.
Yeah, I mean even with buried B and buried E, the 57 and 39 aren't going to go away. (Unless the A is fully restored to Watertown, but even then, I have a feeling the 57 would be retained in some capacity.) That's land that's already devoted to transit -- I have no interest in ceding it back, unless it's to create greenspace.
Makes sense. Sometimes we do have to concede to reality (this isn't the God Mode thread, after all) and we're lucky at least that the existing junction allows access in the Sullivan direction at all, so if a wonky transfer is what we have to deal with, so be it.
I will say, looking more at the "Brickbottom Jct" idea I sketched out, I'm less pessimistic than I originally was. The station would have awful pedestrian access, but it would provide a solid transfer for Medford service. I need to look more carefully.
So many thorny questions and potential problems right around there under the McGrath overpass, that'd be an area where we'd be white-knuckling it waiting to hear the results of the studies. I wouldn't be surprised if we had to settle for only one transfer from Gold; it seems like the GJ version F-Line suggested might be easier because there's somewhat more space there. Though, that would also depend on what kind of grades would be necessary (if it's even possible) to duck under the Fitchburg and then rocket back up to link up to the GLX tracks. A Gold-GJ Inbound to Lechmere-Medford double-transfer would be deeply annoying, but enough improvements to the buses off of the Union Square branch and Orange/Gold could probably mitigate the numbers needing that specific pair.
Yes, I was thinking about bus lanes on Washington St and the extent to which they could mitigate this problem, particularly if the Sullivan-Eastie segment of the Gold Line is a dual-mode transitway -- could you through-run buses, say, from Chelsea to Union Square? That kind of thing.

But yes, the grades at McGrath are going to be tricky no matter how you do it.

The junction between the Union Square/Porter and Grand Junction lines is going to be nasty, since you have to separate the Grand Junction tracks entirely from the Fitchburg Line. No way you're getting a transfer station in there. Inbound, it will be a steep continuous grade from the duck-under of the Fitchburg Line until it meets the Medford Branch tracks.
View attachment 30421
@The EGE, are you doing a flyover or a duckunder here?
 

The EGE

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@The EGE, are you doing a flyover or a duckunder here?
Duckunder. Because of the McGrath overhead, trying to do a flyover would push it to the west. You likely can't lower the Union Square Branch or Fitchburg Line - the Medford Street underpass and the tracks at Union Square station are already prone to flooding.
 

WarpedReality

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Well, to be clear, I am an overenthusiastic amateur with no formal training, so what I think may be quite wrong. :)

Could eminent domain smooth out the curves and shorten the diversion distance? Hmmm, maybe a bit?
Thank you for your very informative reply! It definitely looks like this particular service pattern isn't happening, but I do appreciate knowing exactly why it won't happen.
 

Riverside

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Falling under the heading of "Imagining the Worst Case Scenario", here's a sketch of using Medford Street as the connection between the Union Square branch and the Grand Junction:

1668823769265.png


Requires ~800 feet of elevated over Medford St, or maybe potentially utilizing part of the triangular lot bound by the two RR ROWs and Medford St. I don't think there's quite space between the two buildings in that lot (following the orange dashed path) for two tracks, though maybe you could thread one track through the lot and another track over a narrower elevated above Medford Street.

Depending on where you put the diverges, mayyyyyyybe you could slot a platform on the edge of McGrath? To provide the Union <> Gold transfer that was being discussed upthread.

It allows for gentler curves (and thus faster trains and therefore shorter times blocking the heavily-trafficked segments) than putting the junction further to the east, and allows you to better take advantage of the semi-vacant lot to the north of the ROW.

It very likely is overbuilt. Also, if I were the City of Somerville, I would definitely not be thrilled by an elevated there, especially if there is no station nearby to make it worth the imposition on the neighborhood.
 

Riverside

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I'm spamming my blog a little bit today, but see today's post as topical to several discussions. For this thread, I want to illustrate how Aldgate Junctions can still be insufficient in certain scenarios. You can read in excruciating detail the background, but the practical implications boil down to the following:

An Aldgate Junction is more useful when as many of the following are true:
  1. Branches are evenly distributed geographically
  2. The region is pluricentric, where key destinations are located across multiple branches
  3. The branches are long and form corridors unto themselves
  4. Direct “crossing services” (such as circumferential routes) are not available between the branches, or are too centralized resulting in three-seat-journeys (such as Farringdon-Moorgate-Monument-Cannon Street)
Among other things, this is why, for example, a Comm Ave-Beacon St circulator service seems unlikely to be particularly effective.
 

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