@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.