Well, Boylston could become a major transfer station for GL from the West to GL to Seaport, but that only seems practical, IF there is some way to link the Boylston platforms inside fare control. Boylston platforms could certainly handle the people volume, but the separate directional stations are an issue.
That's why there needs to be an effort to avoid having to ever build a "Boylston Under" like SL Phase III. If you're just reactivating the fence tracks, transfers are as dead-ass easy as they are at Park St. You just re-excavate the filled-in underpass between inbound and outbound sides (closed 1975-ish so the trackbed over the ped tunnel could be strengthened for the weight of Boeing LRV's) and ADA it like the Park IB-OB underpass.
As per my previous reply, if you envision the Tremont St. tunnel reactivation and new Tufts station as a multi-stage buildout, you end up getting most branch patterns covered in the end by eventually using that 4-tracker pipe to relocate the E off the Copley Jct. chokepoint. Which in turn gives you a chance to route a subset of D service off Brookline Village-Riverway connecting trackage. You can have any of the following patterns represented with one-seat service: Heath/etc.-Boylston/etc., Riverside-Boylston/etc. via Huntington, Needham-Boylston/etc. via Huntington, Kenmore Loop-Brookline Village-Boylston/etc. via Huntington, Boston College-Reservoir-Boylston/etc. via Huntington. With Urban Ring Park/GC-Lechmere 'circuit' service and UR Harvard/West-Lechmere having full access from the north.
What does that actually leave out. C's...unless you do some convoluted Kenmore Loop thru-route back out onto the D via Brookline Village and the Huntington connector. But that's slower on a one-seat than just crossing platforms, so isn't a real-world consideration. And B's past the BU East subway station on the UR built, excluding Chestnut Hill Ave. to BC which can be alt-routed via Reservoir and Huntington. Within the scope of a MUCH bigger system, that is not very much left out at all. So when construction costs for a Tremont tunnel reactivation w/Tufts and some TBD South End routing for SL Phase III replacement are factored, both that and the later-phase E relocation cost less than trying to re-mount the original SL III tunneling on a westbound hook-in and impaling itself all over again on the Common. No...you probably won't have all those routing options from Day 1 because the E-relocation cog is probably a second independent project. But given how utterly brutal it is going to be to attempt any sort of Boylston Under whatsoever or anything that SL III attempted to touch in that vicinity, you may indeed get E's-n'-friends aligned for north-south thru-running
sooner and
cheaper playing the hookup options at Tufts rather than getting target-fixated on monolithic builds.
Play the sequence of cog plug-ins @ Tufts with due diligence and the answers get pretty self-contained. Say Tufts is built as the Transitway light rail link-up replacing SL Phase III. Don't think of it as "well, I'm using one pair of tracks and one Tufts platform for the Seaport...the other one is complete surplus." No...what's the next cog? Is it converting Silver Line-Washington to streetcar for Dudley Sq.? Is it the E relocation, and mixed patterns ? Eventually you are going to plug the other track pair and other Tufts platform with other cogs.
Yes. But for me the point is that Bolyston-Park is 4-track and so it makes the most sense to turn back at the "Far end" of the 4 tracking (far end from whichever direction you came from).
From the North/East it makes the most sense to turn back at
Gov Cen...because it has 4 tracks on its North side but only 2 going to park
Boylston...because it have 4 tracks on its North side but only 2 going to Arlington
Kenmore...with a pocket track on the surface so you don't have to slog out the B or C
From the West it makes the most sense to turn back at
Kenmore, on the loop, if you wished you had more service on a branch than the central subway can handle
Park...because demand has tapered off and you've got plenty of platform
Government center...I have a hard time justifying short turns here from the South/West...seems like future demand and current capacity favor turning anything you could have at Gov Center by going to North Sta instead.
And if you 've made it past North Station, going 3 stops to Union Sq seems a fine turnaround.
Following on from above re: the Tufts "cogs", seeing the other 2 tracks and their other platform as strictly "the short-turn" is probably very shortsighted.
How many southbound cogs could there eventually be @ Tufts?
Platform 1
- Boylston/etc.-Silver Line Way w/ SL2 replacement to Black Falcon (6 min. peak headway)
- Boylston/etc.-Silver Line Way w/streetcar to City Point (6 min. peak headway)
Platform 2
- Boylston/etc.-Dudley Sq. via Washington St. (6 min. peak headway)
- Boylston/etc.-Huntington Ave (≤ 6 min. peak headway; primary E pattern + supplemental headway augmentation via Brookline Village)
Should the E alt-route potpourri get especially varied you could even filet a few those slots between Platforms 1 & 2 and work the crossovers past the station down to where tunnels diverge 2 x 2 to keep things in balance. Though because it's also likely that a wye at the tunnel split can alt-route some E's/D's straight to South Station and the Seaport most of the capacity for that variety won't need to be at Tufts-proper.
Now what's available for pair-matching on the north end?
- Medford/etc. via Lechmere
- Union/Porter/Watertown via Lechmere
- UR Northwest Cambridge 'circuit': Park or GC Loop <--> Kenmore <--> Kendall <--> Lechmere/GC
- UR Northwest Harvard/West: Harvard or West <--> Kendall <--> Lechmere/GC
- UR Northeast: Chelsea/Logan Airport <--> Lechmere/GC
Hmm...do you actually have enough bandwidth to change ends on the Tufts platform anymore with 2 full branch schedules + some fileted augmentation feeding each side. That's not Park St. dense, but it's more than a train per every 3 min. on each of the 4 tracks. Probably too tight for short-turning.
And what's that...a 4-on-5 mismarch of south vs. north patterns unless the alt-ed E's pick up the slack? Hold the phone on retiring Brattle Loop...we're probably going to need that.
You can absolutely
start out Tufts with ample short-turning because it's going to take some time to add all the service cogs and pair-match them. But all of the individual matches are high-leverage builds you eventually want, and you are indeed going to build
most of them if not all. Your 50-year traffic modeling considerations are thus that you
can't really consider Tufts replacing Brattle Loop as the only north-to-south turnback, because Tufts' capacity will be spoken-for on thru runs if even 75% of those desired cogs get built. It would be selling yourself extremely short on future considerations.
However...if you
do want to bump that E relocation up on the priority pile just a bit so that cog has a bit more strategic juice behind it, you do ease the pressure eastbound enough that deleting Park Loop looks a bit less risky. But you better damn well be willing to commit to building that Prudential-Back Bay-Marginal Rd. tunnel and get the hell off Copley Jct. in regular service in no less than 15 years if you want to make Park Loop deletion a fail-safe. I don't think they're looking quite far enough ahead right this second to be able to make that level of commitment with certainty.
) Maybe this has been asked before but, how many billions would it take to complete the Circle Line from Medford/Tufts to Riverside through Arlington/Belmont/Waltham????????
