Green Line Reconfiguration

F-Line to Dudley

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Ok so let's go down this rabbit hole. Instead of Essex, use Avery Pl. That curve buys you an extra 200' (give or take) which maybe buys you enough extra grade to where the performance isn't compromised? Or perhaps it doesn't because now you have to go even deeper to avoid building foundations.
No-no-never on thru the Common, as that permitting is what chewed and spat out the Boylston Loop. And the problems to the east with Chinatown underpinning + building foundations + narrow streets are exactly the same. Remember: tunnel depth out of Transitway is totally fixed/unchanging at the threading around Big Dig tunnels with running room to Chinatown unmovably fixing the problematic OL underpin depth. You can avoid Boylston and go deeper to your heart's content west on the Arlington insertion...but the plot was already lost at Chinatown so it doesn't salvage the FTA rating or let you complete design.

Every "Yeah, but..." about some novel new Essex stab (as if there already weren't a thousand of those officially tried) needs to re-read that last sentence in triplicate. The plot is lost by Chinatown... You have to pick a different Orange transfer station than that one; running distance simply doesn't exist from the fixed Transitway insertion to square the underpin.

That means you have no choice but to alternately target Tufts OL as a replacement for infeasible Chinatown. Which drags you south of Essex by necessity, albeit to universally wider streets that won't be nearly such dog-slow running (thus making crow-flies 2D Google Maps perfectionism the ultimate doesn't-matter waste of time). Any "Yeah, but..." that glosses over this necessity isn't rehabbing the project at all to fundable build, so don't waste any target fixation to the West. If you have to touch Chinatown, you're already dead.

Debate ahoy on Stuart St. Redux as that's wholly enabled by a south jog. But the Orange transfer must target Tufts, not Chinatown. Chinatown is a verified impossibility for achieving 100% Design.
 

F-Line to Dudley

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@Riverside...I'm not going to address every micro-point here, because I already did: We're down in the weeds of the weeds getting 6000 moving parts ahead of ourselves hung up on 40 TPH through Park St. as world's-destroying bottleneck under a completism network that won't be seen in any way/shape/form before 2050, if then...and if we could even predict what travel patterns would be with any accuracy in 2050. There's nothing more I can offer as evidence that this is overreading to an extreme, because exactly which traffic interacts at Park is subject to MANY independently-mounted service and build decisions all being enacted and piling on top of each other. Which is neither how anything truly happens in the real world, nor a fixed endpoint when damn near every cog in the Reimagine scheme is thoroughly "choose your adventure" on how you deploy it.

Look...you admit that multi-directional flexi-junctions are the best future-proofing money can buy, and thus probably need to be sited exactly where they are. And given that Bay Vill is part-and-parcel part of the salvage job for fixing SL Phase III's Fed not-recommended rating preventing 100% Design from ever being funded, an arguably necessary step for mending what's broken. That's all fine! Nobody's putting a gun to your head to ever build the E hook-in to Bay Vill Jct. if the traffic modeling doesn't merit that. It's a fucking notch in the wall to evaluate later if/when the shoe fits, and restores our FTA Design funding. That's all. Everything else is future speculation. Just like the unbuilt Post Office Sq. extension still exists 100 years after its cancellation as a fucking notch in the wall at former Charles St. Jct. on the Central Subway that ran hot-and-cold with BTC planners but never amounted to anything. The cover-your-bases expense is all (1) suitably flexible siting of a would-be junction, and (2) fucking notching the wall. No additional overthinking required.

If by posting a potpurri of services you could physically run through there I'm being mistaken for all those services should be run through there...I will STOP posting wholly speculative service scenarios like that forthwith because it's obviously causing major distraction here that's not helping the discussion flow. NO alt-patterned service gets vetted without hard data look at demand and traffic modeling. NONE of the ones I posited as potentials have gotten that data-driven treatment with requisite fullness, nor can skip their place in line at getting their due vetting. If that is not self-evidently understood, clearly that's not the right bait to be flinging around in the thread if scare-mongering about bottleneck what-if's umpteen places down the bucket list is the result. But if you're going to terraform a legacy system to new applications, you better have a wide enough spread of potentials at your disposal for those evaluations because the candidate list will be winnowed by dispatching realities and relative demand in the end. Perfection was never the goal; spread-of-options as door-opener for getting some builds done (like pulling badly-needed SL III and Urban Ring off the mat) are the goal.



So put it this way for however you sketch out your service bucket list from the enabled options. If Park St. TPH is going to be the upending of even a fairly modest network in your traffic modeling...then you are extremely likely going to be an advocate who immediately and full-stop gets behind BLX-Kenmore as a higher-priority future build. Straight-up take the loading that's going Kenmore-Downtown off the Central Subway, straight-up put it onto another trunk with Charles MGH as the Red transfer, and re-center the transfer universe on GC instead of Park. Then backfill Green accordingly with radial traffic and Hynes really being the only intermediate stop not covered by the spread of BLX to the north and relocated E to the South. "Choose your adventure" isn't just an alt-routing game; it's a build priority game, and it's not limited to what's attached to Green. Everything you mention about Park simply fits the profile of one who's going to highly value BLX sooner rather than later and let that shape the bucket list on most-desired Green appendages. This notion that we are embarking on some reckless campaign to blitz-build new service ceilings to ram our heads straight to concussion into is absurd. Work the map...the full map! Let that shape the bucket list. Future-proofing a flexi junction for best potential ROI to try to salvage a lost Design funding rating is not the same as "Jesus Christ...now have this tunnel notch; I simply *must* run myself straight into a problem because reasons!" No...just...no. You pursue the service appendage bucket list that makes the most sense for what you can manage, in whatever sequence tracks with where you see the growth. And if it doesn't pan out, it doesn't pan out. That Post Office Sq. subway tunnel notch isn't bleeding us dry in maint costs after 109 years of disuse.

When I made the obviously badly taken point about Kenmore-Nubian run-thrus I was not advocating that as a service pattern of priority implementation. I was saying that south-half Urban Ring needing to be BRT from lack of suitably effective rail/streetcar ROW's means some wholly other mode exerts gravitational pull on Reimagined Green, too. In that case the need that more limited-capacity BRT be kept free enough from excessive dwells to do its stated job on its best-footing reference schedule...so it is potentially influenced by load-bearing offsets from Green. You then study to square potential with reality, because right now we don't have enough info to make that call. Just because a wraparound Kenmore Looping E provides some easy-grab frequency boost for 66 bus refugees now crossing the Kenmore island via the Harvard Sq. branch and looks like a good idea on-spec does NOT mean the same is a good idea on-spec for Kenmore-Nubian. It just means that you keep tabs on what *potential* tools in the arsenal could help when UR-South now exerts gravitational influence and needs to stay in its lane loading-wise to do its job. That's it; work the map for exploits, and know how to rate the exploits you accrue as either good enough or not good enough to implement. BTC, after all, did that with the Post Office Sq. tunnel notch and decided reverse-branching wasn't the answer.


If the very act of considering the effects of gravitational wells is a source of panic for some assumed "completism" gun to the head...then, what can I say, this is the wrong future-leaning exercise to be engaging in because pants-shitting fear never ended up getting anything useful built. "Parkopalypse" sounds exactly like how Sec. of Trolling Pollack would throw shade at any SL III reboot today so we can continue to watch Downtown slowly drown in escalating double-transferee dwells. Cover the bases, because flexibility has to be prioritized in new steel-and-concrete if we're going to do things like get a rejected FTA funding rating reversed on the Seaport connection. And then just be shrewd with how you use the flex. That's it. I cannot pretend my crystal ball, nor anyone else's, is clear enough to know exactly what degree of completism's Green Line we're going to need to be operating in 2050. I'll settle with Reimagining just transitioning us to a place of more/easier-plug service flex so we choose or not choose where the flex gets plugged in only where/when it's needed to be plugged in. And if that means our Downtown station gravitational wells change in the process...well, DUH!, we've already went down that road giving Red-Blue, NSRL, Silver Line, and UR such high project priorities for their attempts to pull the center of the transfer universe away from Park/DTX with more equitable spread. It fully reasons that any Green-sourced Downtown touches are going to run with the same playbook. How far you push the gravitational reshaping is part/parcel in all this. Pick nits on how much you think the TPH ceiling can be in-situ raised on the Green Line, it also matters the world how the finite-TPH pie is divided by most-wanted demand. Is that not a very different-shaped pie if BLX-Kenmore gets uprated in priority? OK...regardless of one's individual feelings on that one have we not thoroughly established that this isn't a Green-only universe we're making these decisions in? Are we even capable of quantifying NSRL's effects on the 4 color subway lines to know where that future pie gets sliced? No...it'll dump unforeseen new loads in some places, remove loads in others, and generally do both on line segments of all 4. Can we do much of anything today about anticipating those unknowns except prioritizing greater service flexibility in the designs of what we choose build?...probably not. When that flexibility shoe already fits for salvaging SL Phase III project rating and the future brings about all kinds of new uncertainty, Captain Obvious is being rather namesake about the need to bank more flexibility into the LRT system, no?


That's all I have to say on this. I'm bullish on the future if we set up more flex to springboard off of. I'll be long dead before it's time to render one's garments on whether imperceivable future Park St. demand bracketed by a wildly different service universe can conform to a TPH spreadsheet.
 

vanshnookenraggen

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Debate ahoy on Stuart St. Redux as that's wholly enabled by a south jog. But the Orange transfer must target Tufts, not Chinatown. Chinatown is a verified impossibility for achieving 100% Design.
I'm arguing that with a new Stuart St-Tremont St alignment you wouldn't need a transfer to the OL at all. If you're coming from the west then just stay on a train turning north. If you're coming from the east then switch to the RL. Not every crossing requires a transfer. And before anyone says "but it would be nice...", no. It would be nice if this didn't cost billions of dollars. But it does so no.

I guess I wasn't clear enough with my description. The E, via Huntington, would not change. It would swing up to Boylston St and serve Copley and Arlington stations. Then Boylston and Park, on to where ever. The new tunnel would take the B/C/D and swing them just south of Boylston so that you can connect them back into the network with the Tremont tunnel and a branch to South Station. Keeping it hugging the Pike is a bad idea because if you are rerouting so much of the service you need to keep them close to the original stations. There is no reason to dig through Bay Village. First, there is nothing there with transit value. Second, tunneling may be a non starter given the water level problems. The existing tunnels already have to pump water back into the ground to keep the foundations from rotting. More tunnels, especially that Gordian knot clusterfuck, are not the answer. Stuart-Kneeland is the way to go.

Screenshot 2021-01-14 034620.jpg
 
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F-Line to Dudley

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I'm arguing that with a new Stuart St-Tremont St alignment you wouldn't need a transfer to the OL at all. If you're coming from the west then just stay on a train turning north. If you're coming from the east then switch to the RL. Not every crossing requires a transfer. And before anyone says "but it would be nice...", no. It would be nice if this didn't cost billions of dollars. But it does so no.

I guess I wasn't clear enough with my description. The E, via Huntington, would not change. It would swing up to Boylston St and serve Copley and Arlington stations. Then Boylston and Park, on to where ever. The new tunnel would take the B/C/D and swing them just south of Boylston so that you can connect them back into the network with the Tremont tunnel and a branch to South Station. Keeping it hugging the Pike is a bad idea because if you are rerouting so much of the service you need to keep them close to the original stations. There is no reason to dig through Bay Village. First, there is nothing there with transit value. Second, tunneling may be a non starter given the water level problems. The existing tunnels already have to pump water back into the ground to keep the foundations from rotting. More tunnels, especially that Gordian knot clusterfuck, are not the answer. Stuart-Kneeland is the way to go.
Not arguing. Stuart-Kneeland would be one of the study options because of its width. There would be some demerit of needing to bust early out of the abandoned Tremont tunnel and thus being able to use all 4 tracks of the tunnel's capacity to usefulness if a sharp turn or junction were placed, but if the tunneling feet pricing relative to Red-Blue on a similar-width street keeps it under effective control the rest of the way you've checked all boxes and have a winner. I think it's going to fare slightly worse on utility relocation cost than Bay Vill despite BV's greater tunneling feet because it's north of the '65 Urban Renewal nuke zone...noting that utility relocations are such large share of total price tag. But at absolute worst it's a *very* buildable #2 candidate with multiple scenarios where it could easily study out to #1 spot. No one should pretend they know the street innards well enough to make a final call on-spec, so I think you have to state your early preference in terms of #1 and #2 most-feasible builds. Under those odds, Stuart/Kneeland ranks Top 2 in almost any analysis and should get very thorough study attention.


The only thing that has to be emphasized here is that ALL permutations of Essex-Boylston are no-go because of the fixed insertion angle out of the Transitway leaving too little running room to correct the OL underpin blowout at Chinatown. As before...if you predicate anything here on touching Chinatown or the OL tunnel where if awkwardly bifurcates around Chinatown, you're already dead regardless of any/all that happens to the West or is mitigable to the West. So all these posts that claim "self-evidently" that Essex is hands-down best need a reality check.

So...must be a street south of Essex. Your choices (with or without an Orange stop):
  1. Lagrange/Beach to Chinatown Park insertion
  2. Stuart/Kneeland to Chinatown Park insertion (*maybe* some extreme-difficulty cross-block cut to Atlantic bus loop, though that's going to be intrinsically harder than the Park)
  3. Oak to Harrison-or-Hudson then Chinatown Park insertion
  4. Marginal to Hudson/Chinatown Park insertion
Some of these will be considerably more valid than others, but those are the 4 debateworthy choices for all Transit Pitching. It just can't be another broken-record stab at Essex. That ship sailed when the FTA downrated it and made funding 100% Design there an impossibility.


EDIT: Re: Atlantic bus loop being pinched out by adjoining Big Dig tunnels, this is the far more likely trajectory for your Kneeland alignment (blue anno):

EDIT.png


It's 100% impossible as Kneeland + bang-onto Atlantic; Big Dig tunnels cover all possible insertion into the Transitway. Scrub that one off the map, because the convergence of above/below tunnels sealing off any insertion angle doesn't even allow one to squint harder at that trajectory to find a way. The only alternatives are:
  • The "official" provisioned SL III junction on the Atlantic to Surface Rd. blocks of Essex gutted & cleanroomed during the Big Dig. Any selection of streets west of the tip of Chinatown Park is fair-game, but trajectory is set in stone here for the Transitway tie-in. Blue annotation would be shared by any Kneeland OR Bay Vill trajectories.
  • Potential...but longshot...ability to cross diagonal off Kneeland on the mid-blocks between Surface Rd. & Atlantic to hit East St. at the southern extent of the SL loop. Manifold difficulties trying to do this with sharp angles and building foundations on those blocks, but *theoretically* possible where as bang-up on Atlantic from Kneeland intersection is 100.00% impossible.
I think you're taking the set-aside SL III provision to the tip of Chinatown Park as a practicality because it's hands-down going to be cheaper/easier than any mid-block kludges and impossibility is sealed for lower Atlantic. Means you have to square a turn at Harrison or Hudson and make it look 'joggier' on a 2D map, but the turn angles @ the Park and into the Transitway are gentle enough to take a trolley at-speed so as long as the turn from Kneeland isn't too sharp it'll be a good performer. Probably still faster than the Essex SL III alignment where the max-steep grades on the Chinatown underpin was a bona fide schedule-wrecker making total mockery of the 2D crow-flies directness. So, in the end, not a consequential edit that you won't be getting mapmakers' perfectionism on the turn into SS.
 
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Riverside

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If by posting a potpurri of services you could physically run through there I'm being mistaken for all those services should be run through there...I will STOP posting wholly speculative service scenarios like that forthwith because it's obviously causing major distraction here that's not helping the discussion flow. NO alt-patterned service gets vetted without hard data look at demand and traffic modeling. NONE of the ones I posited as potentials have gotten that data-driven treatment with requisite fullness, nor can skip their place in line at getting their due vetting. If that is not self-evidently understood, clearly that's not the right bait to be flinging around in the thread if scare-mongering about bottleneck what-if's umpteen places down the bucket list is the result.
That's not what's happening here, and I hope you won't stop with your posts -- they do definitely help the discussion.

But, and this is the last time I will say this, this isn't a problem of "what-if's umpteen places down the bucket list." As I laid out very specifically, with the bare minimum of expansions, you already cross the current theoretical capacity limit. Then the question becomes, "Okay, so how do you increase capacity at Park Street?" Your answer is "By reducing dwell times through reduced transfers due to expanded through-run one-seats and transfers available elsewhere." And my response is, "Okay, but even a very modest number of non-controversial expansions would require a pretty significant increase; that's a lot of juice to squeeze out of the fruit of reduced dwell times -- do we really think that will be enough?"

And not for nothing, but these concerns have been raised publicly in the past when Green Line expansions have been proposed. My take is that they were often used as a bogeyman, but it's still a very obvious objection to raise. Your very reasonable answer is that we can't predict the future well enough to answer the question, and that's fine. Like I said, I'm skeptical, but also practically not in any disagreement about what we should prioritize building.

What I am saying: as an addition to the list of ideas we toss around here, we should have exactly the discussion that you and Van are having now about whether there is any way to send westbound trains someplace other than Park. I think it's a higher priority than you do, but I don't think it's a five-alarm problem. I think the problem is subtle and hard to discern, which is why I've belabored it, but don't mistake that for saying that this needs to be solved today.

This board has, through its conversations and collective wisdom, developed really innovative ideas that I don't see discussed elsewhere. The Bay Village loop (even without a SS hook-in), the Red Line X, and most of the Reconfigured Green Line ideas are great examples of elegant solutions to tricky problems. I'm teeing up what I think is a tricky problem and suggesting we see if we can find an elegant solution. You don't think it's a tricky problem, and that's fine.

--

All that being said, the more I think about it, the more I feel that the best solution would simply be to short-turn most Kenmore services on the inner Park Loop, if push comes to shove. Reserve the outer tracks for Tremont services that through-run north, so you get good traffic segregation. Kenmore services get their Blue Line connection at Kenmore, so there's less of a need to go all the way to GC. That would then leave the Tremont services pretty pair-balanced with most possible northside branches: Nubian-Chelsea, Riverside/Huntington-Woburn, Needham/Huntington-Waltham, and Seaport to wherever -- maybe short-turned at Porter, or maybe run to Watertown, or just divvied up among the other branches. I think most of the Kenmore branches are poor candidates for through-running to the northside, so it's parsimonious with that as well.

--

In general, something I've come to appreciate more about the Reconfigured Green Line concept is that it treats the Green Line more like a series of nodes than as a series of lines. Consider for example the reverse-branching service to Forest Hills that F-Line and I agree on -- Forest Hills to Back Bay and beyond, and Forest Hills to Kenmore. A hypothetical MFA-destined rider waiting on Centre St sees a northbound train coming. She sees that it's heading to Kenmore, but she gets onboard anyway -- she knows that when gets to Riverway (or Brookline Village), they'll be a high number of MFA-destined trains -- coming in from maybe four different sources (Kenmore, Riverside, Needham, Forest Hills) -- that she'll be able to transfer to, so it won't be a long wait.

If the expectation is that a journey that passes through a node like Brookline Village or Bay Village will, about 50% of the time, entail a transfer (even when executing the same journey -- depending on what destination train you board in the first place), and the system is designed to take that into account -- low wait times, reasonable platform design -- then I really do think the Reconfigured concept can sing. (Because of the lack of Comm Ave access to the Kenmore Loop, you cannot do this on those branches, and that is a weakpoint I wish we could address.)

--

@vanshnookenraggen thanks, that does make more sense. My gut reaction to that crossover just south of Copley is negative for its inelegance (crossing with no transfer), but I could get on-board. Certainly this would address my desire for a new western outlet for Kenmore trains.

How would you hook in a leg to Nubian?
 

nick

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How would you hook in a leg to Nubian?
That was my question, too.

A second question: Why terminate Blue at Kenmore? Why not continue down Brookline Ave and terminate at Brookline Village to pump D/Needham through Huntington? If heading into the heart of Longwood, D/Needham riders would transfer at Brookline Village to Blue, sure, but travel times would be a wash because of a much more central station location at Brookline/Longwood compared to the current D Longwood. Provides a faster connection for northside RL and OL riders heading to Longwood, and probably reduces a lot of demand for shuttles/future BRT connecting to Lansdowne.
 

Riverside

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A second question: Why terminate Blue at Kenmore? Why not continue down Brookline Ave and terminate at Brookline Village to pump D/Needham through Huntington? If heading into the heart of Longwood, D/Needham riders would transfer at Brookline Village to Blue, sure, but travel times would be a wash because of a much more central station location at Brookline/Longwood compared to the current D Longwood. Provides a faster connection for northside RL and OL riders heading to Longwood, and probably reduces a lot of demand for shuttles/future BRT connecting to Lansdowne.
Blue-beyond-Kenmore is probably better suited for the Crazy Transit Pitches thread. For a number of reasons, Blue-to-Kenmore is very obvious and relatively straightforward, but beyond-Kenmore is murkier -- is it better to go to Brookline Village, or to Allston? And from Allston, where beyond that? So that's why we typically break the Blue Line extension up into those two separate parts. Focus on building the Kenmore extension first, and then see where we go from there.

You're not wrong about sending D + Needham to Huntington, but you don't need a Blue-to-Brookline Village extension to make that work -- you can either reroute one of the two Highland Branches up to Kenmore, or you can add a short-turn Green Line branch out of Kenmore that either terminates at Brookline Village, or runs up around to Reservoir, or goes east to any number of places.

A subway under Brookline Avenue is soooooo tempting but also sooooooo expensive, and sooooooo duplicative of a ROW just a half-mile away... hence why that goes into Crazy Transit Pitches.

If you build a full subway under Huntington Ave, then that can probably provide your faster connection for northside RL and OL riders.

Yes, in a hypothetical full-build 100-year future, you probably want to send the Blue Line somewhere beyond Kenmore. But this thread is really about short/medium-term improvements to enable structural changes in the Green Line to facilitate flexibility and expansion for the rest of this century, so Blue-past-Kenmore is less pertinent. Blue-to-Kenmore is needed for a lot of Green Line Reconfiguration proposals, but not so much beyond-Kenmore.
 

Bananarama

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Would a Green Line branch to Allston make more sense? Just continue onto Brighton Ave from Commonwealth B line. A separate Blue extension that way seems redundant.
Blue running down Brookline Ave would be nice to give actual Fenway the Fenway stop (it's currently weirdly out of the way and not central to all the density being built down Brookline and Boylston).

Is there a reason for doubling up lines on top of each other other than expediency of the below grade one? Or are you suggesting just replacing the Green E entirely with Blue subway?
 

Riverside

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Would a Green Line branch to Allston make more sense? Just continue onto Brighton Ave from Commonwealth B line. A separate Blue extension that way seems redundant.
Blue running down Brookline Ave would be nice to give actual Fenway the Fenway stop (it's currently weirdly out of the way and not central to all the density being built down Brookline and Boylston).

Is there a reason for doubling up lines on top of each other other than expediency of the below grade one? Or are you suggesting just replacing the Green E entirely with Blue subway?
I'm gonna reply to this in Crazy Transit Pitches.
 

vanshnookenraggen

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How would you hook in a leg to Nubian?
Just extend it down Tremont like normal. Branch capacity here isn't as much of an issue as it would be for, say, the Red Line.

An argument could be made for a free transfer between all three Copley-Back Bay stations.

My GL reconfigs always included connecting the D to the E on Huntington. If you did that each "trunk" of the GL would see two balanced services. With one branch from Stuart going to South Station you open up a full branch to Nubian.

Screenshot 2021-01-14 154410.jpg
 
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Riverside

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Just extend it down Tremont like normal. Branch capacity here isn't as much of an issue as it would be for, say, the Red Line.

An argument could be made for a free transfer between all three Copley-Back Bay stations.

My GL reconfigs always included connecting the D to the E on Huntington. If you did that each "trunk" of the GL would see two balanced services. With one branch from Stuart going to South Station you open up a full branch to Nubian.
Yeah my question wasn't about capacity but about the physical linkage. It sounds like implicit in this proposal is that the Tremont tunnels would need to be reworked to add a flying junction at Stuart Street, ignoring the current abandoned flying junction a bit to the south. That's a downside, though not necessarily a fatal one.

And yes -- you and I take the same approach with regard to Huntington. The long-term vision should be an extended Huntington subway that hooks into the D Line.
 

vanshnookenraggen

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Yeah my question wasn't about capacity but about the physical linkage. It sounds like implicit in this proposal is that the Tremont tunnels would need to be reworked to add a flying junction at Stuart Street, ignoring the current abandoned flying junction a bit to the south. That's a downside, though not necessarily a fatal one.
This is a valid consideration. I was always working under the assumption that this could be done. If not, I'll accept a Bay Village alignment. BUT UNTIL THEN!

Here is a more reasonable alternative which doesn't redirect the GL B/C branches. While this would certainly be easier to build, I'm more cautious because I don't know if it would serve ridership demand as well (I mean it could, I just don't know.)
The real question is what kind of O/D is there between Allston/Brighton and South Station/SBW vs Brookline/Fenway/JP and South Station/SBW? If the correlation is more between Back Bay and SBW then it doesn't matter. But if there are more riders coming from the west to SBW then this doesn't really help them (although if this is the case then more RR service on the Worcester Line might just take care of that). I suppose if this was all built out and you added the Needham Branch to the GL then at least you could still have a OSR from Needham to South Station!

Screenshot 2021-01-14 161915.jpg
 

Riverside

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Yeah, I dunno if a new flying interchange at Tremont & Stuart is possible. I'm not pessimistic per se, but it's less elegant than the Bay Village's parsimonious reuse of the double portal + flying junction extant in the Tremont St subway.

For your updated proposal -- I played with something similar and called that Huntington-Seaport line the "Teal Line" (because it's Green but goes near the water). The downside I saw was that the Huntington corridor (and feeding services, i.e. Highland Branches) ends up with no or reduced connection to the Blue Line; this could potentially be mollified by clever reverse branching (or a tunnel to the airport), but it's a bit tricky.

The advantage of having some sort of crossover between Huntington-originating trains and Kenmore-originators -- whether it's at Copley or Boylston or whatever -- is that it guarantees a connection to Blue at Kenmore and at GC for Huntington. In a parallel topology, like you have here, that becomes harder to swing.
 

vanshnookenraggen

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For your updated proposal -- I played with something similar and called that Huntington-Seaport line the "Teal Line" (because it's Green but goes near the water). The downside I saw was that the Huntington corridor (and feeding services, i.e. Highland Branches) ends up with no or reduced connection to the Blue Line; this could potentially be mollified by clever reverse branching (or a tunnel to the airport), but it's a bit tricky.

The advantage of having some sort of crossover between Huntington-originating trains and Kenmore-originators -- whether it's at Copley or Boylston or whatever -- is that it guarantees a connection to Blue at Kenmore and at GC for Huntington. In a parallel topology, like you have here, that becomes harder to swing.
There's where we differ. I, under no circumstances, see the value in extending the BL past Charles/MGH. Especially with a Stuart St Subway which actually serves places people want to go. Send it to Cambridge or don't do anything at all.

I'd have to see what the O/D is between the BL and the Huntington Ave corridor. Given the hospitals there it probably isn't trivial. But Huntington would still have one line that would hit Govt Center (one line with more service, mind you.) My fix for this was to have a shuttle from Brookline Vil to Kenmore.
 

Riverside

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I see where you're coming from. And yeah -- like I said, it's not fatal to have only a subset of Huntington trains with a direct connection to Blue (which is a problem regardless of whether you have a Blue-to-Kenmore extension or not), it's only a drawback.

You'll note that in my original sketch, I excluded the Teal Line from the Tremont Subway altogether, with the aim of addressing capacity and reliability by segregating the LRT Highland Branches from the streetcar B/C etc Lines. Those benefits would come with their own drawbacks too.
 

vanshnookenraggen

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I see where you're coming from. And yeah -- like I said, it's not fatal to have only a subset of Huntington trains with a direct connection to Blue (which is a problem regardless of whether you have a Blue-to-Kenmore extension or not), it's only a drawback.

You'll note that in my original sketch, I excluded the Teal Line from the Tremont Subway altogether, with the aim of addressing capacity and reliability by segregating the LRT Highland Branches from the streetcar B/C etc Lines. Those benefits would come with their own drawbacks too.
Given the 4 track trunk of the GL and the loop at Kenmore it's possible to have a max of two branches for each trunk line AND add a branch to Allston-Harvard. Yeah, it forces C riders to have to transfer at Kenmore. Not that I think this needs to happen given ridership west of Kenmore; I think you can have three branches and not worry about interlining. But if there is a noticeable imbalance in ridership on one branch then you could deinterline (bi-interline?)
 

Riverside

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I was more looking to segregate traffic based on reliability, rather than be concerned per se about capacity. Even with traffic signal prioritization, the B/C (plus any resurrected A to Oak Square) are going to be qualitatively different in their reliability and character than the Highland Branches or even a modern branch to Nubian. More stops, closer together, generally lower ridership per stop, interactions with traffic (and vulnerabilities to, ah, right-of-way obstructions)... in a 50-year future, the Highland Branches could be renovated to Los Angeles-style high level platforms, which is much less likely to happen on Commonwealth and Beacon.

I'm hardly saying it's a must-have, but if there develops a way to let the LRT network become a bit more customized to the needs of its specific corridors -- rather than the current approach which essentially finds an (un)happy medium between all of them -- I'd be very keen.
 

George_Apley

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Here is a more reasonable alternative which doesn't redirect the GL B/C branches. While this would certainly be easier to build, I'm more cautious because I don't know if it would serve ridership demand as well (I mean it could, I just don't know.)
The real question is what kind of O/D is there between Allston/Brighton and South Station/SBW vs Brookline/Fenway/JP and South Station/SBW? If the correlation is more between Back Bay and SBW then it doesn't matter. But if there are more riders coming from the west to SBW then this doesn't really help them (although if this is the case then more RR service on the Worcester Line might just take care of that). I suppose if this was all built out and you added the Needham Branch to the GL then at least you could still have a OSR from Needham to South Station!
You could also help B/C-->SBW in this alt if there was a Huntington-Kenmore via Brookline Village short-turn that would give them a 2-seat ride.

Lots of options... now we gotta get the Commonwealth to study it... 😅
 

Arlington

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For that new tunnel for the Aqua Line (!), is there any chance it could come down Columbus and then gently turn before the pike to pass under Frieda Garcia Park and then the Back Bay Garage (on the cityside of the pike) to form a better "superstation" with the OL/CR at that point?
(I'd have it take the space currently occupied by the "Trinity Place Westbound Onramp"
 
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vanshnookenraggen

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You could also help B/C-->SBW in this alt if there was a Huntington-Kenmore via Brookline Village short-turn that would give them a 2-seat ride.
Eh, that would require a long back track that no one would make.

Ok, I've drank the Bay Village kool-aid.

Screenshot 2021-01-14 181240.jpg


I think my concern about water table drop can be mitigated if the new GL tunnel is close enough to the surface below the Mass Pike frontage roads. You probably have enough clearance to built a flying junction at Tremont St and go above the OL as it passes below the Pike. I thought about a station between the two GL branches (E and F) here but my concern is that the new F Line now has to dive so quickly to get under the OL that you might not have the grade for a station there (similar issue as up at Essex St.) No transfer here really only affects riders from the South End to SWB which I've always argued is a very small number (although does SL4 ridership justify this? Asking for a friend.)

I'm still arguing that you don't need a transfer to the OL at Tufts. Interlining allows for parallel service to the OL so just stick with a OSR. The new Washington St station should probably be between Washington and Harrison too.

As much as I would prefer to have any new tunnel closer to the CBD I can also see the potential that if built under Stuart St it would butcher ridership on the Boylston St section too much.

Also the loop at South Station is shown as in service. This is just me being too lazy to change it. Could do loop service if you want.
 

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