Is the volume of freight traffic large enough that restricted hours would be a major problem? I know there is some, an in addition to Amtrak being very unhappy that means full subway conversion isn't happening, but I don't think it's enough that night operations would be insufficient.
The plan, back from the "Indigo Line" proposal, was to move the Readville platform off the Fairmount-Franklin connector north about 500 ft. with a south tip aligned with the Hyde Park Ave./Milton St./driveway intersection. Then drop an island platform in the gap between the current mainline track and the freight lead. They'd then re-interlock the tracks north and south of the platform so both sides of the platform are accessible from any train and also to/from either the Franklin or NEC connectors (the NEC connector does exist and is used by the last Stoughton revenue train of the night). Then add a third-track turnout at the south interlocking so the backing-up freight trains miss the platform (Franklin Line to the Readville backup is a protected high-and-wide freight clearance route).
The only freight inbound of Readville Yard was a nocturnal switch of the cold storage warehouse at Widett Circle, done on the 1:00am-5:00am shift. That customer has been idle for 2-3 years, and they were only getting weekly deliveries when they were using rail. So right now there's nothing whatsoever. Should Marine Terminal get its Massport rail spur off Track 61, the extant Readville-Widett slot would simply go 6 nights a week and be extended to Southie. It's understood that because of crossing Southampton Yard and the Old Colony main at-grade that CSX would never be able to do a daytime freight there, and it says so in Massport's feasibility study about the Marine T. spur.
Great analysis. First, a few minor points:
That still leaves the (Admittedly not great) option of just, not stopping at Boylston, but this could create problems with overcrowding Park St.
I'm not sure 5 min headways are actually unworkable. Some quick digging turned up this paper which mentions bunching on the Silver Line, pointing out that the biggest problems for reliability are:
Good points. Let me try to keep this one quick.
Both are detailed in the F-Line proposal above. The supposed "Harvard-reserved ROW" (despite little amounts of official details) would allow no street running in mixed traffic in Lower Allston, and grade separation at all junctions via open cuts. So the only temporary part would be street-running north of the river and on the Anderson Bridge (Kennedy St).
Well, if you want to do the phased-build approach that F-Line suggested, it will have to be light rail regardless (at least initially). But the other reason is what the branch will connect to beyond West Station and BU, as discussed below.
Like I already said in the buses thread, I'm very pessimistic that a full deep-bored tunnel that's almost 4 miles long (Harvard-LMA via 66) is gonna fly in today's political climate. But aside from that:
Some good points, although I'd like to clarify a misunderstanding that I wasn't very clear about: I don't think the full 4 mile tunnel is what should be built. I think we're generally in agreement that a tunnel across LMA is desirable, nor is it impossible. (Although again, it would need to be deep bored, not C&C.) This would end up being probably around 1.25 mi. The line would then surface, follow i90 to West Station, then travel on the surface/elevated across Harvard/Lower Allston, (As shown in the plan linked), before diving into a final short tunnel to link up with the existing tunnel at Harvard. This ends up being ~1.5 mi of tunneling.Moving this discussion here since it's clearly no longer about "MBTA Buses and Infrastructure".
Both are detailed in the F-Line proposal above. The supposed "Harvard-reserved ROW" (despite little amounts of official details) would allow no street running in mixed traffic in Lower Allston, and grade separation at all junctions via open cuts. So the only temporary part would be street-running north of the river and on the Anderson Bridge (Kennedy St).
The permanent solution that he gave does seem to require a tunnel. From a very quick search, it looks like cut-and-cover across rivers* is actually not as hopeless as you may think, though I haven't looked into the details yet. But regardless, if such a proposal comes from @F-Line to Dudley - who's famous for its cost-consciousness to the point where some proposals may seem to be from a dollar store - then I have more confidence that it can be done at reasonable costs.
* Shanghai has always been an interesting case to me in terms of construction. Like Boston, it also has a very complex set of conditions underground, to the extent where "experts" from decades ago deemed that the city wasn't suitable for subway construction. Yet, it now has 18 subway lines and is actively building more. Not sure how much of their land was filled, so can't make a comparison to Boston yet, but I'm far from an expert on subway construction anyway.
Well, if you want to do the phased-build approach that F-Line suggested, it will have to be light rail regardless (at least initially). But the other reason is what the branch will connect to beyond West Station and BU, as discussed below.
Like I already said in the buses thread, I'm very pessimistic that a full deep-bored tunnel that's almost 4 miles long (Harvard-LMA via 66) is gonna fly in today's political climate. But aside from that:
For one, both @F-Line to Dudley and @Riverside (where that map I linked came from) are explicitly assuming that a cross-LMA tunnel will not be built. F-Line has written various pieces on why he thinks a cross-LMA tunnel is literally impossible. You're free to disagree with them - and I'm generally more optimistic of a cross-LMA tunnel than they are - but this helps understand the context.
For another, even if a cross-LMA tunnel does get built, the question is: what do you use it for? This is best illustrated with the following proposal from @The EGE, who is indeed optimistic on a cross-LMA tunnel as a "Crazy Engineering Pitch":
(All pieces from The EGE on this topic: one, two, three)
The idea: A cross-LMA tunnel is just as desirable for a radial route (via Huntington) as it is for a circumferential route, if not more. This route gives you direct access to the heart of LMA from Back Bay, South Station, North Station and Seaport... All big names. Even with as much circumferential service as you can realistically build, majority of LMA commutes will likely still come from the downtown core via transfers.
And the best part is: You don't have to choose whether you're doing a radial route or a circumferential route - you can have both! As elegantly shown above. But you'll only reap this benefit if you build it as (heavy-metro, grade-separated) LRT.
I realize that "LRT vs HRT" is a separate question from "TBM vs other grade-separated methods". But TBM isn't the definitive answer to the second question either - as The EGE sketched above, there is a theoretical possibility to land the tunnel on the Highland Branch. Then it may be possible to do a low-cost approach to land onto a Comm Ave subway, where C&C is definitely doable due to no utilities. That gets you to the BU bridge. If this is feasible, it's the cheapest way by far to navigate through the LMA-Kendall segment, while still giving you grade separation all the way to Main St Cambridge (or possibly Mass Ave if you're pessimistic about that one).
Finally, circling back to the original point of the Harvard branch: Whether cross-LMA is built as a TBM subway doesn't reduce the cost of a full LMA-Harvard subway. Yes, you may save some fixed costs, but my prior belief is that variable costs of TBMs are just as much as fixed costs if not more. It's not like you get the other 3 miles of subway for free if you build the 0.5-0.8 mile cross-LMA.
(Note: I have to say that I'm increasingly skeptical of the Highland-Longwood wye shown above, specifically, about flood mitigations for opening up a portal on the Highland Branch just next to the river. It's possible that the northern lag may need to be tunneled under Brookline Ave instead, while the southern lag need to be underground beneath Highland until Aspinwall Ave. Regardless, most of my points still stand.)
Assuming GLRC, this (mostly) already exists. It's the Green Line. Yes, the walk from the Longwood/LMA stops is not ideal. But is eliminating it it worth permanently nuking 50% of capacity for on the entire rest of the line for? An orbital line would (Likely) serve places like Nubian, Kenmore, Kendall/Harvard, and potentially more. Again, also big names. Not to mention you're now linking the main orbital route, which is basically "The backup plan" in case something goes wrong on the GL, with the GL.
While the question of "whether a 10-min walk from an 'LMA' station to hospitals is good enough" bears discussion, I think the same also applies to a circumferential route. There's nothing innate about riders from Harvard, Allston, Ruggles, Nubian etc that make them deserve a doorstep LMA connection more than riders from North/South Stations, Malden, Maverick etc. So if walking from LMA is reasonable for the latter, it's also reasonable for the former, at which point you save the expense of the cross-LMA subway altogether. In fact, this is exactly what @Riverside's map is hinting at: a low-cost solution that still provides access to LMA from all quadrants, possibly layered with additional services for circumferential riders going beyond LMA (e.g. T28 to Kenmore) and/or street-running routes across LMA (the 'H' Crimson Line in that proposal).
I don't think I agree with this, at least in this specific case where (At least to some extent) "LRT" means "Connecting to the GL" and "HRT" means "Not doing that"
This is a fair point. If an orbital line could be built without the deep-level subway under Longwood that may be preferable. I'd be concerned about whether or not this is possible though given the fens and generally swampy nature of the area though. But you're right, it's not that Nubian/Harvard riders deserve a shorter walk, it's that a rail connection is needed between the two, with a stop at Longwood on the way. Given that, if the cost of adding a stop in the center of Longwood vs the periphery is about $0, then that's obviously preferable. If that is not the case, and an alignment that passes through Longwood rather than around the edge is significantly more expensive, then it's much more tricky.
To clarify, I meant that the combined frequency of both circumferential BU-LMA-Ruggles trains and radial Reservoir-LMA-Back Bay trains (i.e. the maximum capacity that can be handled by a single trunk) seems to be better (or at least more easily doable) than the equivalent for HRT (e.g. Ashmont and Braintree trains combined, or the entire Orange Line).
| Route | Pros | Cons |
| Via Roxbury Crossing | Could C&C under Malcolm X Blvd, making the intermediate tunnel cheaper | Loses out on CR connection and local ridership |
| Via Ruggles | Connects to CR and local ridership at Northeastern | May require a TBM for the Nubian-SW Corridor section |
| Route | Pros | Cons |
| Nubian-South Station via 93 |
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| Nubian-Seaport via Widett Circle/South Boston Bypass |
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| Nubian-Southie via Widett Circle/Andrew |
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| Nubian-JFK/Columbia Point via Newmarket |
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| Station | Pros | Cons |
| Harvard |
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| Central |
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| Kendall |
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| Route | Pros | Cons |
| Via Kenmore |
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| Via Coolidge Corner |
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| Via Lower Allston (And CC) |
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Excellent Discussion.
In my recent fantasy map the option I went with for serving Chelsea was a full C&C subway under Broadway, which generally does a better job of hitting the major locations in Chelsea compared to the SL3 alignment. It can also be extended further into Revere Center, another major location with extremely high bus ridership that would significantly benefit from better transit.
Yeah, the southern half of that is similar to what The EGE proposes:
And there are a lot of potential alignments you can do for that, but yeah, I'd connect it to a new heavy rail subway under Congress St.
I swear it’s purely coincidence I mentioned the EL on Rt 1 in the other thread and you’re showing a line along the same route here
. I’ve always imagined your red line diverting from Rt 1 briefly along Everett Ave to a large, consolidated Chelsea Sta. at Mystic Mall. I think that‘s prime land for a sort of “New Downtown” for Chelsea, and you can maintain a good connection the current downtown with a station at the Rt 1/Everett Ave interchange