Crazy Transit Pitches

[Riverside]

So here's a crazy transit pitch that I realized this morning has been tossed around but never really examined: build a second LRT tunnel between Back Bay and Boston University. Such a tunnel (connected at the eastern end to a subway under Marginal Rd, with connections to the Pleasant Street tunnel and the Seaport) would significantly increase capacity on the western end of the network, enabling new branches to the Grand Junction, Harvard, and a reactivated A Line (via West Station) to avoid capacity constraints in the Central Subway altogether.

(The aforementioned subway under Marginal Rd, which also would serve the Huntington branches, would then become a pinchpoint, but if needed that could potentially be remedied with a double-stack subway to enable quad-tracking to Shawmut Ave, after which the split off to the Pleasant St tunnel will relieve pressure.)

I am not sure this is feasible; there are several sections, each with their own challenges.

Back Bay Station to Dalton Street -- going under the Pru

As far as I know, the only path through here has been carved out by the Mass Pike and the B&A railroad tracks. So if this is going to work, I think it would require a subway under the Pike itself. I have no idea how feasible this would be. Also note that a flying junction would be needed around Exeter St to hook in the Huntington branches. Also note, as always, that this is landfill.

Dalton Street to Charlesgate East

A couple of considerations here. First, a decision would need to be made about whether and how to interface with the Hynes Convention Center station. Since our LRT tracks would likely be on the north side of the Pike anyway, it might be feasible to veer slightly north away from the Pike to connect to the station. Also note that in this pocket we are actually not on landfill anymore -- this was the "Gravelly Point" peninsula.

Then you have a choice -- travel via Kenmore, or via Lansdowne?

Charlesgate East to Kenmore

Yeah, I have no idea how feasible it would be to widen the S-curve under Charlesgate to add an additional 2 tracks.

For Kenmore Station itself, probably you'd want to look at a second level below the current station, and futureproof it to interface with a Blue Line extension; the upper level supports 4 tracks, so you're okay width-wise from a footprint perspective.

Make sure you add crossovers or the like to support short-turns (ideally from both directions, but especially from the west).

Kenmore to BU Bridge -- a new subway under Commonwealth

Extending the subway under Comm Ave has been an idea for over 100 years. Comm Ave itself is extremely wide, well over 90 feet between sidewalks, which should be more than enough for a quad-track subway -- two tracks to Copley and two tracks to Back Bay. Arrange them right, and you might even avoid a flying junction at BU Bridge -- just put your Back Bay tracks on the northern half of the quad. (Of course, ideally you can swing a flying junction to enable a WWEE track layout with shared center platforms for each direction, to make waiting for the right train easier.)

Once at the BU Bridge, you can branch off to West Station and Grand Junction like we've been discussing for years. (For example, here.)

Charlesgate East to BU Bridge via Lansdowne

I think this stretch is relatively homogenous. And I think you basically have three choices:

1) Subway under the Pike (if you can with the landfill, and also dealing with closing half the Pike during construction and also with ducking under the Beacon St Subway)
2) Claiming lanes on the Pike -- would basically entail grabbing three lanes, plus a little more for a stop at Lansdowne. The Pike is 8 lanes wide, plus a breakdown lane, for most of this stretch, so it's not necessarily impossible, but....
3) Running over the Pike at street-level and/or with overpasses on cross streets; this will cost you at least partial air rights, plus will be expensive, plus would introduce some challenges with grade-crossings. Light rail plays nicer with traffic lights than other rail, but still less than ideal

An alignment via Lansdowne would have a couple of station-siting-related challenges:

1) Difficult to add useful connection to either Kenmore or to the Lansdowne commuter rail station
2) Difficult to create a usable transfer station at Boston University

If I were king...

I would put the Pike on a road diet under the Pru, reclaim 25 feet for LRT track, hook into Hynes station, then expand the tunnel under Charlesgate to support 4 tracks, add a second level beneath Kenmore and then extend into a 4-track subway under Commonwealth.

~~~

So, is there any other way under the Pru? Can the S-curve be expanded to 4 tracks? Should the Pike be put on a diet?

 

[Teban54]

So here's a crazy transit pitch that I realized this morning has been tossed around but never really examined: build a second LRT tunnel between Back Bay and Boston University. Such a tunnel (connected at the eastern end to a subway under Marginal Rd, with connections to the Pleasant Street tunnel and the Seaport) would significantly increase capacity on the western end of the network, enabling new branches to the Grand Junction, Harvard, and a reactivated A Line (via West Station) to avoid capacity constraints in the Central Subway altogether.

(The aforementioned subway under Marginal Rd, which also would serve the Huntington branches, would then become a pinchpoint, but if needed that could potentially be remedied with a double-stack subway to enable quad-tracking to Shawmut Ave, after which the split off to the Pleasant St tunnel will relieve pressure.)

I am not sure this is feasible; there are several sections, each with their own challenges.

Back Bay Station to Dalton Street -- going under the Pru

As far as I know, the only path through here has been carved out by the Mass Pike and the B&A railroad tracks. So if this is going to work, I think it would require a subway under the Pike itself. I have no idea how feasible this would be. Also note that a flying junction would be needed around Exeter St to hook in the Huntington branches. Also note, as always, that this is landfill.

Dalton Street to Charlesgate East

A couple of considerations here. First, a decision would need to be made about whether and how to interface with the Hynes Convention Center station. Since our LRT tracks would likely be on the north side of the Pike anyway, it might be feasible to veer slightly north away from the Pike to connect to the station. Also note that in this pocket we are actually not on landfill anymore -- this was the "Gravelly Point" peninsula.

Then you have a choice -- travel via Kenmore, or via Lansdowne?

Charlesgate East to Kenmore

Yeah, I have no idea how feasible it would be to widen the S-curve under Charlesgate to add an additional 2 tracks.

For Kenmore Station itself, probably you'd want to look at a second level below the current station, and futureproof it to interface with a Blue Line extension; the upper level supports 4 tracks, so you're okay width-wise from a footprint perspective.

Make sure you add crossovers or the like to support short-turns (ideally from both directions, but especially from the west).

Kenmore to BU Bridge -- a new subway under Commonwealth

Extending the subway under Comm Ave has been an idea for over 100 years. Comm Ave itself is extremely wide, well over 90 feet between sidewalks, which should be more than enough for a quad-track subway -- two tracks to Copley and two tracks to Back Bay. Arrange them right, and you might even avoid a flying junction at BU Bridge -- just put your Back Bay tracks on the northern half of the quad. (Of course, ideally you can swing a flying junction to enable a WWEE track layout with shared center platforms for each direction, to make waiting for the right train easier.)

Once at the BU Bridge, you can branch off to West Station and Grand Junction like we've been discussing for years. (For example, here.)

Charlesgate East to BU Bridge via Lansdowne

I think this stretch is relatively homogenous. And I think you basically have three choices:

1) Subway under the Pike (if you can with the landfill, and also dealing with closing half the Pike during construction and also with ducking under the Beacon St Subway)
2) Claiming lanes on the Pike -- would basically entail grabbing three lanes, plus a little more for a stop at Lansdowne. The Pike is 8 lanes wide, plus a breakdown lane, for most of this stretch, so it's not necessarily impossible, but....
3) Running over the Pike at street-level and/or with overpasses on cross streets; this will cost you at least partial air rights, plus will be expensive, plus would introduce some challenges with grade-crossings. Light rail plays nicer with traffic lights than other rail, but still less than ideal

An alignment via Lansdowne would have a couple of station-siting-related challenges:

1) Difficult to add useful connection to either Kenmore or to the Lansdowne commuter rail station
2) Difficult to create a usable transfer station at Boston University

If I were king...

I would put the Pike on a road diet under the Pru, reclaim 25 feet for LRT track, hook into Hynes station, then expand the tunnel under Charlesgate to support 4 tracks, add a second level beneath Kenmore and then extend into a 4-track subway under Commonwealth.

~~~

So, is there any other way under the Pru? Can the S-curve be expanded to 4 tracks? Should the Pike be put on a diet?

Question: What makes you think Commonwealth Ave warrants a 4-track subway instead of a 2-track one?

 

[JeffDowntown]

Question: What makes you think Commonwealth Ave warrants a 4-track subway instead of a 2-track one?

You have two destinations both directions West/Grand Junction, Copley/Back Bay. The flying junction is out near the West/Grand Junction branching. Need Quad tracks to operationally accomplish the directions.

 

[Riverside]

Truth be told, I proposed a quad under Comm Ave because I did the math wrong. Strictly speaking from a capacity perspective, 2 tracks would probably be fine: the tunnel would only need to support a max of 4 branches (BC, Oak, Harvard, Grand Junction), which should be doable on 2 tracks. 4 tracks of course would set you up for that much more capacity down the line, but the only “crayon map” branch I could ever imagine being in the universe of possibilities would be a branch to Watertown via West Station staying north of the Pike (using Western Ave or N Beacon St). Probably not worth the expense.

That being said, it may be that with the various junctions, it still makes more sense to separate the tracks. (@JeffDowntown I think this is what you’re getting at?) Oak and BC trains would be headed for “Kenmore Middle” while GJ and Harvard trains would be going to “Kenmore Under”, and I don’t think it’s worth worrying too much about enabling revenue crossover service between the two “pipes”. So, from that perspective, it may be more parsimonious to just go with quad tracks rather than a bunch of flying junctions.

 

[JeffDowntown]

Truth be told, I proposed a quad under Comm Ave because I did the math wrong. Strictly speaking from a capacity perspective, 2 tracks would probably be fine: the tunnel would only need to support a max of 4 branches (BC, Oak, Harvard, Grand Junction), which should be doable on 2 tracks. 4 tracks of course would set you up for that much more capacity down the line, but the only “crayon map” branch I could ever imagine being in the universe of possibilities would be a branch to Watertown via West Station staying north of the Pike (using Western Ave or N Beacon St). Probably not worth the expense.

That being said, it may be that with the various junctions, it still makes more sense to separate the tracks. (@JeffDowntown I think this is what you’re getting at?) Oak and BC trains would be headed for “Kenmore Middle” while GJ and Harvard trains would be going to “Kenmore Under”, and I don’t think it’s worth worrying too much about enabling revenue crossover service between the two “pipes”. So, from that perspective, it may be more parsimonious to just go with quad tracks rather than a bunch of flying junctions.

I think without separate tracks your junction options get too convoluted. That was my intent. Do all the routing back at the GJ/West area.

 

[luobo]

So if we're talking about LRT from Mattapan up Blue Hill Ave, would it be worth it to wiggle up Warren St to Nubian and up Washington St to downtown?

You'd end up a GL branch to Ashmont (via Nubian and Mattapan). You eliminate the isolated fleet, the only tricky part is figuring out how to go through Warren St, and you don't ruffle as many feathers on the Mattapan/Milton end.

Having a J-shaped line that goes south to Mattapan and then north again to Ashmont is a little odd though.

 

[737900er]

One of the issues I see is the length. It would be a bit over 6 miles from the portal to the Mattapan. B is a little over 4 miles from Blandford Street to Lake Street. Even with a modernized design it would still run into operational issues, and the trip lengths to/from the end would be quite long. That might be ok if there was an intermediate place to connect to it (e.g. if Orange ran to Nubian), but that's not going to happen. Introducing another line as unreliable as the B into the Central Subway also wouldn't be great.

For these reasons, I'm a proponent of RoxCrossing/Ruggles-Nubian-Mattapan-Ashmont LRT. It's not a one-seat-ride to downtown, but it would be much faster and more reliable than any one seat ride ever reasonably could be, and connects to Orange, Green (F), Indigo, and Red. It would be about 5 miles from Mattapan, but wouldn't get in the way of other services. Like the current Mattapan line it could be operated as a Green Line division but branded as something else, and there would be non-revenue connections to the F at Nubian.

 

[ulrichomega]

You'd end up a GL branch to Ashmont (via Nubian and Mattapan). You eliminate the isolated fleet, the only tricky part is figuring out how to go through Warren St, and you don't ruffle as many feathers on the Mattapan/Milton end.

The Warren St issue always seemed overblown to me. Other LRT systems seem to have no problem temporarily ducking into C&C tunnels or onto temporary elevated structures (obviously the tunnel would be preferable here). There are convenient medians on either end where the ROW would be going anyway for portals. And if the trains are going to have to go down that street anyway I see no reason a tunnel wouldn't be the perfect solution for this short stretch.

 

[ulrichomega]

Having thought about this a bit more:

The stop spacing around the tunnelled section would be reasonable. About 3000 ft spacing, which is about double what they just rebuild the BU stops as. Depending on whether they're trying to match existing station spacing ala the B&C lines, or longer, more LRT-esque station spacing ala the D Line, GLX, and existing Mattapan Line, this is fine. It's slightly long, but with stations at either portal it's not the end of the world. Pictured is a more-spaced version of what this might look like, with the obvious caveat that station spacing and where to go after Nubian can be completely arbitrary.

 

[737900er]

Apart from the tunnel it doesn't seem like a very crazy transit pitch to me!
Not having to build any stations in the tunnel would help keep construction costs way down.

 

[ulrichomega]

Apart from the tunnel it doesn't seem like a very crazy transit pitch to me!
Not having to build any stations in the tunnel would help keep construction costs way down.

I agree! It's a perfectly reasonable transit pitch, however it involves the spooky spectre of actually pouring concrete, and is therefore Crazy on these forums.

In all honesty, the mysteries about the northern end of such a branch are enough to actually cement it in Crazy town for me. Needing to re-open the Pleasant St portal in some form is going to be a large undertaking, and a GL extension this long is going to induce operational problems no matter where it ties in (though at the very least a use of the Pleasant St portal would enable the branch to use the less-used outer tracks at Boylston, which reduces conflicts with other branches at least a little). And speaking from a "This will actually never happen but wouldn't it be cool if" scenario, it greatly complicates the possible existence of a potential Marginal St/Stuart St/Other subway to create a second GL mainline through Back Bay, as was discussed over in Green Line Reconfiguration recently.

Barring a Pleasant St portal re-opening, I'm not sure where it could go. The Roxbury Crossing/Ruggles connection is an intriguing one, as a short section of track would enable it to connect to the E. I'm not suggesting through-running along a RoW out there, but it would enable yard access to the main GL facilities. Of course, extending it up through downtown along Washington would be great, but that would require the powers that be to actually give a damn about enforcing bus/trolley lanes, or the reconfiguration of numerous streets to create a dedicated RoW. Which is absolutely worth it and needs to be done anyway. Leaving such a line as a Nubian->Ashmont stub would also be... fine. You'd need to either rejigger the Mattapan yard to handle an increased fleet or probably find some space elsewhere to house it. The yard property looks big enough, but a lot of it is used for other purposes now, and I'm not sure how feasible a conversion would be. Or heck, it literally goes to Codman Yard. Carve out a little space there if possible (yes, I'm aware they're currently reconfiguring that yard for increased Red Line storage).

EDIT: Oh, and I hope this doesn't need to be said, but obviously the full extension to Ashmont conflicts with any possible Red Line extension that also uses the Mattapan HSL. I think that's probably the better investment here in terms of raw dollars-to-transit, but Milton's reticence to any changes would probably honestly lead to two separate lines both terminating in Mattapan, rather than a combined line or a replacement by the Red Line.

 

[Tallguy]

Why would re-opening Pleasant St be difficult?

 

[Tallguy]

But going up Seaver to Columbus to Jackson and possibly to Huntington at Ruggles could be center dedicated lane the whole route.

 

[ulrichomega]

Why would re-opening Pleasant St be difficult?

From an engineering perspective you need to reactive a portal that hasn't been used in a long time. There's going to need to be upgrades to make, and the portal was north of the Pike, so how do you cross that? Or do you create a new portal south of the Pike and just use the existing flying junction as opposed to the original portal? If you use the original, how do you get from Washington St to Shawmut? So you're either dealing with a new tunnel under the Pike (basically impossible due to the Orange Line and NSRL reservations you'd need), or you're doing fairly cheap but operationally expensive surface improvements. The line south of the Pike is easy to figure out. North of there is hard.

Hard is not impossible. Hard is just harder than taking an already wide rode and laying trolley track down the middle along with a short tunneled section.

EDIT: I use the word "impossible" in this post in the same sense that it's been used numerous times on this forum: Hard to accomplish and therefore will not happen due to political realities. For this I apologize and will be deleting my account forthwith.

 

[Riverside]

From an engineering perspective you need to reactive a portal that hasn't been used in a long time. There's going to need to be upgrades to make, and the portal was north of the Pike, so how do you cross that? Or do you create a new portal south of the Pike and just use the existing flying junction as opposed to the original portal? If you use the original, how do you get from Washington St to Shawmut? So you're either dealing with a new tunnel under the Pike (basically impossible due to the Orange Line and NSRL reservations you'd need), or you're doing fairly cheap but operationally expensive surface improvements. The line south of the Pike is easy to figure out. North of there is hard.

Hard is not impossible. Hard is just harder than taking an already wide rode and laying trolley track down the middle along with a short tunneled section.

Detailed in excrutiating detail here and here in the thread you yourself mentioned earlier, based on previous studies and my own (admittedly non-professional) analysis. There are several alternatives presented, most of which do not actually require reopening the Pleasant Street Portal, but instead reusing the bellmouths into a new tunnel. (And, as you mentioned, the alternatives I propose are specifically designed to future proof for a Marginal Subway.)

The NSRL portal (as F-Line explains in the linked thread) would be to the east around Harrison St, and would not be impacted here. Digging under the Pike is indeed hard but not impossible.

If we are deadset against tunneling under the Pike (which obviously can be done, since the Orange Line does the same), then Alignment B in the second link still provides a portal north of the Pike and doesn't actually require eliminating Eliot Norton Park.

It's true that the tunnels themselves will need some rehabbing after 60 years of disuse. But I don't think it's nearly as mysterious as you are suggesting.

 

[ulrichomega]

I'm not saying connecting to the Tremont subway is impossible, just that it's harder than laying track in a median. But as you say most proposals for a new line to Nubian don't involve reusing the portal, and instead require a lot of much more complex tunneling than I was proposing on Warren St. (especially if we're future-proofing for future subways, which we should).

I'm not sure of where the hostility here is coming from. Is this really a contentious statement to make? I'm 100% in support of any and all efforts to do anything possible to extend rapid transit to Nubian and points south, but it is a complicated project.

EDIT: Ugh, I'm sorry. I see where I said tunneling under the Pike was basically impossible. That was wrong. I was under the impression that the NSRL portal was closer to Back Bay, since my understanding was that NSRL needed every bit of horizontal space it could get to make the grades work. I can't see F-Line's posts, but I'll assume he's correct here. I'll stand by my statement that it is harder than laying tracks in a median, though.

EDIT2: I will actually contest the "portal around Harrison" statement. The latest study has the portal between Shawmut and Washington, right where we'd want things to go. Now you're obviously already going under the Orange Line around there, so depth isn't a major concern, but underpinning a second tunnel would be.

 

[Riverside]

Regarding LRT on/under Warren St: I think this is a very complicated discussion -- both from a transit design perspective, and from a social-political one. Remember, in recent memory there was significant community opposition to the "28X" BRT proposal. Am I saying that we should never propose BRT or LRT on Blue Hill Ave again? Absolutely not. What I'm saying is that an LRT line will run into many of the same objections, and a good proposal should have some way to address them.

Two transit design notes: first, and probably most importantly for a tunnel under Warren: where are you going to put the portals? (I talk about this the least, but it's also one of my biggest concerns.)

Second, a Mattapan-Park St LRT line would parallel a Fairmount Indigo Line at well-less than a mile away for its entire stretch south of Columbia Road; the infrastructure for a one-seat ride to downtown already exists -- does it need to be duplicated on a mode that will be slower?

Finally, it's worth recognizing that the transit network in Dorchester is unique in Boston. Three northern terminals (Nubian/Ruggles, Egleston/Jackson/Ruggles, and Forest Hills) are each linked to both southern terminals (Mattapan and Ashmont), with almost every route featuring very high frequencies all day. These routes overlap to form a lattice, in a structure that basically does not exist anywhere else on the T. (I wrote at some length about the unique features of this network back in late 2020.) It is not trunk-and-branch.

Building a rapid transit spine down the center of this network would not have the same network-realigning effect that (for example) GLX to Medford is likely to have. Green-on-Blue-Hill handles one pair (Nubian-Mattapan, though only sorta), but you'd still need to keep your other routes pretty much exactly as they are: Nubian-Ashmont, Jackson-Ashmont, Jackson-Mattpan, Forest Hills-Ashmont, Forest Hills-Mattapan. And honestly, you probably need to keep your Nubian-Mattapan buses too, if you're going to do rapid transit spacing. Plus, there's the fact that a huge fraction of these riders actually go to Ruggles, not Nubian -- my skim of the data suggests the split is roughly 50/50.

(And, by the by, LRT from Nubian is not likely to be faster than staying on the bus and transfering at Ruggles.)

So... an LRT line from Park ends up serving:

• Blue Hill Ave & Warren St riders heading downtown who are able to walk to a rapid transit-spaced stop but are not able to walk to a more distant but also more centrally located Fairmount Line stop
• Blue Hill Ave & Warren St riders heading directly to Nubian
• Blue Hill Ave & Warren St riders transferring to a different bus at Nubian

But doesn't help

• any riders to Jackson Square
• any riders to Ruggles
• any riders who need to transfer to a different bus at Ruggles
• any riders to Longwood
• any riders to Forest Hills

This is my point about the Dorchester network being a lattice. It is true that the 28 corridor comes in first place in ridership... but all the other corridors are not far behind at all. The 28 corridor looks like it is a trunk line, but it really is more complicated than that.

I highly recommend reading the Better Bus Profiles for the different routes we're talking about here. Another piece of the puzzle that comes through in those profiles: there is major ridership turnover on these routes -- many people aren't going to Nubian at all but are traveling locally from one point on the corridor to another. An LRT line will help some of those folks with a slightly faster ride, but many will continue to prefer the bus as its local stop spacing will get them closer to their destination (and likely will come more frequently than a Green Line train would anyway)

I don't mean to come across as hostile, so I apologize for that. Laying track in a newly-created median on Blue Hill Ave between Mattapan and Franklin Park Zoo? Sure, yes, from an engineering perspective that is probably easier than the work at Pleasant (easier from an engineering perspective but maybe not from a political one). Likewise, LRT tracks on Columbus and Seaver -- building on existing bus lanes -- would probably be similar.

A new cut-and-cover tunnel down a narrow street in a dense residential neighborhood, along a stretch of street that sees more buses than (I believe) anywhere else in the system that would all need to be diverted and delayed during construction, and many -- if not all -- of which would still be needed following completion of the LRT line... that is much harder. Add that on top of the number of transit journeys that this won't really improve at all... my point is that, even if the tunnel is feasible (but again, portal locations), it's far from obvious to me that this is the best way to improve transit in Dorchester.

(Sorry for wall of text and for possibly hostile tone -- I don't mean to come across aggressively. Like I said, I just think there are a lot of layers here.)

 

[ulrichomega]

No worries, your post just put me on the defensive.

I'll agree that the political realities of such an LRT line would be... fraught. The 28X was a disaster that everyone involved really should have learned from. I was aware the bus network down there was a lattice, but the sheer extent of it was actually kind of eye-opening. I still think there's some utility in a line directly downtown, but I'll fully admit that this is pencilling in on a map and not real transit advocacy.

RE: The frequency comments. Even assuming that some connection gets made to downtown, I think I would still argue for Nubian short-turns to increase frequency on the rest of the route. Or, heck, even separate the line into two. Nubian/Ashmont and Nubian/<somewhere north of Boylston>. The lessons of the Fairmount Line's not-as-SS-centric-as-you'd-expect existence should be learned here. The bus network tells the transit story here, as you say, and it says that intra-neighborhood transit is important here.

RE: Portals: I say just put them on either end, outside of the narrow section of Warren. My map has them located about where I'd put them. On the north end, north of Townsend/Quincy streets where the large median exists today. On the south end, you'd need to either do a large rework of the Geneva Ave. intersection or tunnel under Blue Hill Ave until you're south of Washington (though that stretches out what's already a long stop spacing).

 

[Riverside]

No worries, your post just put me on the defensive.

I'll agree that the political realities of such an LRT line would be... fraught. The 28X was a disaster that everyone involved really should have learned from. I was aware the bus network down there was a lattice, but the sheer extent of it was actually kind of eye-opening. I still think there's some utility in a line directly downtown, but I'll fully admit that this is pencilling in on a map and not real transit advocacy.

RE: The frequency comments. Even assuming that some connection gets made to downtown, I think I would still argue for Nubian short-turns to increase frequency on the rest of the route. Or, heck, even separate the line into two. Nubian/Ashmont and Nubian/<somewhere north of Boylston>. The lessons of the Fairmount Line's not-as-SS-centric-as-you'd-expect existence should be learned here. The bus network tells the transit story here, as you say, and it says that intra-neighborhood transit is important here.

RE: Portals: I say just put them on either end, outside of the narrow section of Warren. My map has them located about where I'd put them. On the north end, north of Townsend/Quincy streets where the large median exists today. On the south end, you'd need to either do a large rework of the Geneva Ave. intersection or tunnel under Blue Hill Ave until you're south of Washington (though that stretches out what's already a long stop spacing).

For what it's worth, I think there is a stronger argument for an LRT line that is explicitly built to terminate at Nubian or Ruggles rather than through-running. However, as I think it was @Charlie_mta who pointed out, an LRT journey between Franklin Park Zoo and Ruggles is much easier to accomplish traveling via Egleston rather than Nubian. Wide streets all the way, connection to the (faster) Orange Line much sooner for those looking to transfer, direct connection to the transfer hub at Ruggles, and better proximity to employment centers in Longwood.

Plus -- even if such a route terminated at Ruggles (which I'd argue it should), it would still be able to connect to revenue Green Line tracks at Jackson Square. How does the Green Line get to Jackson Square? Via a half-mile extension from Hyde Square -- itself an extension that, as I understand it, enjoys reasonable community support and has some credibility at an official level.

All that being said: the City won a grant last fall to design and build center-running bus lanes on Blue Hill Ave and I believe the T has plans underway to expand the Columbus Ave bus lanes. So it will be interesting to see how those projects pan out.

 

[ulrichomega]

Update on Portals location:

I'm not sure this is as possible as I was thinking. Basing things off the B and C portals, we'd want ~500 feet of travel to get down to the right depths. That's just not possible without major rework on either end.

On the south end, you'd have to start your portal almost in the middle of the Grove Hall intersection and by the time you get down to the Washington St intersection you've got almost enough space, coming in at a bit under 400 ft. It's possible that some reworking of the grid here could help (such as allowing a central median/portal across the Washington St intersection similarly to the Geneva Ave one), but I'm sure the community response to such a project would be harmful to the project.

On the north end, I'm completely stumped. It seems like you'd be able to do the same thing with turning Hazelwood into a southbound-only connection to Warren, but you're basically at MLK by the time you're up high enough, pushing your platforms even further north.

The extra portal length turns a 3000ft station gap into a 4000ft one. That seems too far without an intermediate station, and a station box on Warren seems like a cost blowout waiting to happen. I'll stand by the pitch as "Crazy", but it's definitely moved towards the harder end for me.