Green Line Reconfiguration

[Teban54]

Yeah, this is a reasonable analysis. The bigger remaining analysis, in my opinion, is indeed the scenario where Needham only runs via Huntington surface.

That's actually an interesting point. In that case, a Needham rider's options would be:

• Take the N all the way to Copley via Huntington surface: 18 min
• Take the N to Newton Highlands, and transfer to the next D: 3.75 + 14 = 17.75 min
  • Assume D and N trains are spaced evenly, and each runs 8 tph

So it's a wash, but considering the time from Brookline Village to Riverway, in practice transferring to the next D probably wins. The question is how many people are willing to make such a transfer and turn one-seat rides into two-seat rides.

On the other hand, we know from the Rail Vision study that Needham (and West Roxbury etc) rejected an alternative that gives them commuter rail service every 15 minutes but requires a forced transfer at Forest Hills. This seems to indicate that they'll likely take the OSR instead of transferring to the D to save maybe 1-2 minutes.

 

[Teban54]

Anyway, while revisiting the 2003 Program for Mass Transportation (PMT) that evaluated a huge number of projects, I found this:

Absolutely wild. I can't believe this was a real-world proposal. Apparently, it was indeed proposed by the city of Boston.

A Silver Line BRT tunnel extension from South Station (branching out from SL Phase 3) to Back Bay (via Stuart St) and then to Kenmore, where it rises to the surface and runs in two branches: one to LMA via Brookline Ave, and another to Brighton Center via Comm Ave, Soldiers Field Rd, Cambridge St and presumably the 57 corridor.

It's already wild to think about a second tunnel from Back Bay to Kenmore (though, of course, @Riverside has proposed it before), much less doing it for a bus!

Yet, the idea actually does very well on ridership, enough to net it "medium priority". To put 27,900 projected daily riders in perspective:

• Higher than BLX to Lynn (21,000) and SL Phase 3 itself (20,500)
• Much higher than Red-Blue (6,500), GLX (8,400), Arborway restoration (14,200), Needham branch (3,400), OLX Reading (9,400), OLX West Roxbury (11,300), and RLX to 128 via Arlington (6,700)
• Comparable to another (crazy) idea of merging the 23 and 28 into Silver Line (29,300)
• Only 4 rapid transit projects have higher ridership: Urban Ring Phase 3 (134,700) and Phase 2 (53,000), NSRL (96,100), Nubian surface LRT (34,300), and the aforementioned SL23/28

Where did this (very high) ridership come from? My guesses:

1. Rapid transit connection between LMA, Back Bay, South Station and Seaport
   • Though LMA involves surface running
2. Provide relief to Kenmore and BU for the Green Line, and giving them new connections to South Station and Seaport
3. New branch to Brighton that basically restores the A branch
4. Allston Landing development

Sound familiar? That's exactly why I posted it in this thread.

The most important benefits of this proposal -- that contribute to its projected high ridership -- can be achieved equally well, if not better, with Green Line Reconfiguration.

• #1 is enabled by GLR, specifically the service pattern to Seaport (the Magenta Line on my map).
• For #3, looks like the main reason Brighton is mashed into this project (instead of as the A branch) was due to the Green Line having no additional capacity. GLR addresses that.
• #4 can be supported with Grand Junction LRT, and if there's a huge need for a radial rapid transit connection from West Station, it should be easy to put a Kenmore branch there.
• The only thing not addressed directly is #2 (Kenmore).
  • However, GLR already alleviates Kenmore's capacity needs by diverting some traffic (particularly the D) to Huntington.
  • And if a Kenmore-Seaport OSR is desired, there are variants of GLR that allow it.

Even better, GLR likely won't have as much cost, due to not needing to tunnel between Back Bay and Kenmore, and not needing to modify Kenmore itself. (Even a surface Huntington branch should do the job as well as this proposal's Brookline Ave surface-running.)

• Their projected cost of $540 million for a 2-mile tunnel, part of which is under the Pike, seems way too low to me... Until you realize that their GLX projection was $375 million.

To me, this provides some support that Green Line Reconfiguration will indeed have good ridership. With LRT having higher capacity than BRT (and likely higher frequency if the Huntington-Seaport route can run every 3-4 mins), and improvements to service on every other Green Line branch, I expect eventual ridership to be even higher, even though likely not at the level of NSRL or the (much more expensive) Urban Ring Phase 3 tunnel. Even better if you also include Nubian LRT's ridership.

 

[TheRatmeister]

Anyway, while revisiting the 2003 Program for Mass Transportation (PMT) that evaluated a huge number of projects, I found this:
View attachment 47059

View attachment 47060

Absolutely wild. I can't believe this was a real-world proposal. Apparently, it was indeed proposed by the city of Boston.

That is completely insane. Really goes to show how prominent the BRT craze was in the 2000s. Just the mental gymnastics you would need to go through for this...

 

[F-Line to Dudley]

That is completely insane. Really goes to show how prominent the BRT craze was in the 2000s. Just the mental gymnastics you would need to go through for this...

At the time of the Access Boston study and the PMT, SL Phase III was already a-go (the PMT didn't even evaluate it because it was *assumed* to be thrashing along already). But it was before the problems during design started mounting with degraded vehicle performance in the tunnels, tunneling alignment straw-grasping, heinous cost blowouts, and so on. As well as failing to predict the existing Transitway's poorish vehicle performance and loading problems (it hadn't opened at the time). Even if they had evaluated SL III fully, the actual ridership would've severely lagged the projected ridership because of the resulting extreme slowness of the trips and the need (because of the degraded performance) to force-loop all ends at Boylston Under rather than run thru and hit all the subway transfers and all that Red/Orange ridership. The existing SL Washington underperformed by half its projected ridership because of the lack of behind-prepayment subway transfers to 3 of 4 lines like originally promised. You were probably looking at at least a 35-45% underperformance of SL III's projections if it couldn't hit the Green+Orange+Red trifecta on a thru trip because of the forced Boylston loopage, and probably half or more for "SL West" when the slashed roster of transfers collided headfirst with the poorer-than-originally-predicted bus performance.

The assumptions for "SL West" were thus built on a total house of cards, and assumptions making an ass out of U and me. The City generally doesn't run as robust transpo studies as the state does, so the methodology in the Access Boston source document was probably hella flawed to begin with. But the PMT should've known better and applied much more rigorous screening for this one. A big blight on an otherwise authoritative-over-time document of most-needed transit projects, but as you say...the BRT kool-aid was free-flowing in the late-90's and early-aughts.

"It's just like rail...except it has tires!"

 

[Teban54]

At the time of the Access Boston study and the PMT, SL Phase III was already a-go (the PMT didn't even evaluate it because it was *assumed* to be thrashing along already).

Actually, the PMT did include SL Phase III. The alignment at that time included the Boylston loop and then going via Tremon St. Interestingly, its new ridership projections fell short of both Nubian LRT and this SL West proposal.

degraded vehicle performance in the tunnels

I actually wanted to ask: looks like buses can theoretically handle steeper grades than LRT, but I recall that you said before about how LRT running via Essex would have less punitive performance constraints than BRT. Is it because LRT can run faster when climbing up the tunnel, even though it's closer to the maximum grade that it can handle?

and probably half or more for "SL West" when the slashed roster of transfers collided headfirst with the poorer-than-originally-predicted bus performance.

To be fair to them, the PMT map drew the SL West extension via Stuart instead of Essex. While it's not clear how they intended it to branch off from the "completed" Silver Line, the map shows SL West starting at Washington St while SL Phase III uses Tremont St further west. If they did intend SL West to branch from SL Phase III near the Surface Rd vicinity and bypass Chinatown, it would have been much more feasible.

 

[Riverside]

That's actually an interesting point. In that case, a Needham rider's options would be:

• Take the N all the way to Copley via Huntington surface: 18 min
• Take the N to Newton Highlands, and transfer to the next D: 3.75 + 14 = 17.75 min
  • Assume D and N trains are spaced evenly, and each runs 8 tph

So it's a wash, but considering the time from Brookline Village to Riverway, in practice transferring to the next D probably wins. The question is how many people are willing to make such a transfer and turn one-seat rides into two-seat rides.

The bigger concern I have is travel time relative to the commuter rail. From Needham Center today, the CR takes 41 minutes to South Station. Via Kenmore, my guess is that the Green Line to Park St would be 47 min via Kenmore and 51 min via Huntington. That's not terribly slower, and of course the frequency increases would mean more flexibility and (in some sense) less waiting. But it does make me slightly reticent to reroute Needham commuters from the CR to a surface-running version of the E.

Spoiler: measuring to Back Bay/Copley instead of South Station/Park St

The comparisons do slightly better when measured to Back Bay: CR is 35 min, Kenmore is 40 min, and Huntington is 44 min. But only slightly.

It's already wild to think about a second tunnel from Back Bay to Kenmore (though, of course, @Riverside has proposed it before)

Hahaha, "proposed" is maybe a strong word... "idly examined" is perhaps better.

To me, this provides some support that Green Line Reconfiguration will indeed have good ridership

This is a very interesting and thought-provoking analysis! Will need to look more closely and ponder.

 

[F-Line to Dudley]

I actually wanted to ask: looks like buses can theoretically handle steeper grades than LRT, but I recall that you said before about how LRT running via Essex would have less punitive performance constraints than BRT. Is it because LRT can run faster when climbing up the tunnel, even though it's closer to the maximum grade that it can handle?

The grade difference between modes isn't that much. The performance difference is that rail is on a fixed guideway while buses have to steer in-line, so the bus isn't going to go as fast as the train up the grade. It's a speed restriction on bus that wouldn't be on rail. The bus in SL Phase III already gets clobbered by the tightness of the Boylston loop (because of the need to minimize digging on the Common), and the less-than-advertised performance in the existing Transitway (which, extrapolated, means that performance on most of SL III needs to be knocked back accordingly). It couldn't afford any more performance demerits, but the tunnel stacking and maximally steep climbing grades at Chinatown served up exactly more of that.

 

[BlazingZack]

Hi! I'm somewhat of a recent (past year) lurker who only started getting interested in MBTA maps and future projects like this after discovering Van's maps, and eventually Riverside's. I know this has been discussed like 1000x over but I still don't completely understand why, but can someone explain to me *why* a LRT green line connection under essex to SS and the transitway doesn't work? Forget any BRT or bus loop, but what exactly is the issue with (a la Van's original map I believe) going down after Arlington, having some sort of station(s) at or between Boylston (under) and Chinatown, and then rising to meet SS and the Transitway?

I know the agreement here seems to be the Gold Line route, but to me, it does seem to be a problem to not have any sort of B line/C line/Kenmore and onwards connection to South Station/Seaport.

 

[Riverside]

^ Let me see if I can beat @Teban54 on the reply here

can someone explain to me *why* a LRT green line connection under essex to SS and the transitway doesn't work

First off, welcome to the board! I'm glad this is interesting, and I'm touched to hear that my maps contributed.

An Essex Subway is one of those things that seems workable until you start looking at all the things you would need to mitigate.

1) Width: you need one or two stations to provide transfers to Boylston and Chinatown stations. The logical place for one is in the block between the two. But, the buildings there are barely 50 feet apart across the street, which might barely be wide enough for a surface level station, but is too narrow for a single-level subway station. So, we say, no problem, just stack the platforms on top of each other. But that leads you to...

2) Depth changes: now you have one of your platforms all the way down at Level -3 (below the Green & Orange tracks, and then below the first platform). That already means that you are digging a deeper tunnel (see below), which makes it more expensive. And now you need that tunnel to rise up from -3 to fit over the Big Dig Tunnel and then be able to hook in with the transitway. IIRC, that is physically doable, but much more complicated, which is a problem on a project that will need lots of...

3) Building mitigations: Essex St is old, and the buildings along it are old, and a new subway -- particularly one that goes 3 levels down -- will need to dig away right next to those old buildings, down along and probably deeper than their foundations. Each building will require its own set of measures to keep it from collapsing during and after construction, which will be expensive and complicated. Plus, as an old street, Essex likely has unmapped utilities and other surprises waiting for us down there. And that's not even considering the special mitigations needed for...

4) Underpinning Boylston and Chinatown stations: by digging under the stations, you'll need to find a way to hold them up while you dig and keep them held up after you finish. More time, more complexity, more money, particularly given how old these stations are. And it becomes even more painful when you realize that you need to do it for two levels' worth of new tunnels. You'll also have to figure out how to build a transfer connection down to the new subway (including all the way down to Level -3), which... I don't even know how you would do that at the existing Boylston station -- those platforms are pretty constrained and don't even have a free transfer between inbound and outbound

I'll be honest, I needed to go back and double check myself before answering, which speaks to one of the annoying things about the feasibility of the Essex Subway concept: there's no single fatal flaw, but rather a bunch of problems stacking up on each other until the whole thing becomes impractical. (F-Line will argue that the underpinnings were the fatal flaw, and I don't necessarily disagree with that, but my point is that even if you can find a way to solve that particular problem, there will still be multiple others fighting you.)

And, also frustratingly... it's not that the Essex Subway is absolutely or physically impossible to do. Given enough money and time, yes it probably could be built. But the question is, how does it compare to potential alternatives (including no-build)? And by extension, would the money & time spent on it be more effective if spent elsewhere?

It's definitely an unsatisfying combination of, "Yes this could be done in theory" and also "It would be so expensive and difficult that it'd be hard to justify when compared to other projects". And also yeah, it looks really nice and clean on a map. But it just becomes harder and harder the more you look.

Does that make sense? Sorry for the TED Talk (though I imagine you knew to expect that by now, lol).

I know the agreement here seems to be the Gold Line route, but to me, it does seem to be a problem to not have any sort of B line/C line/Kenmore and onwards connection to South Station/Seaport.

This remains, as ever, the annoying fly in the ointment. Because, yeah. It's an unaddressed need. @Teban54 has an idea for a modification/elaboration of the Gold Line proposal to enable Kenmore <> South Station -- I think his is an interesting proposal and also would bring its own set of complications.

For my part, I've tried to address this in two ways. First, building a direct transfer between Copley and the new Gold Line platforms at Back Bay. This would be in the neighborhood of 800 feet, which is long, but IIRC is comparable to the Orange <> Blue transfers at State.

The second is to just straight up extend a BRT surface route along Essex. Like, South Station actually is pretty darn close to the Green Line -- about 2500 feet between South Station and Boylston. That's just not that far. With some good BRT infrastructure in place, Kenmore riders can get the 2SR to the Seaport that most other riders across the system would also enjoy via transfers to the Gold Line, SL3, and a Congress St busway.

 

[Teban54]

Hi! I'm somewhat of a recent (past year) lurker who only started getting interested in MBTA maps and future projects like this after discovering Van's maps, and eventually Riverside's. I know this has been discussed like 1000x over but I still don't completely understand why, but can someone explain to me *why* a LRT green line connection under essex to SS and the transitway doesn't work? Forget any BRT or bus loop, but what exactly is the issue with (a la Van's original map I believe) going down after Arlington, having some sort of station(s) at or between Boylston (under) and Chinatown, and then rising to meet SS and the Transitway?

I know the agreement here seems to be the Gold Line route, but to me, it does seem to be a problem to not have any sort of B line/C line/Kenmore and onwards connection to South Station/Seaport.

Warmest welcome!

The narrower scope of using the particular Essex St corridor is way too expensive due to cost overruns, as F-Line explained here and here. At the time of SL Phase III's cancellation, its cost had risen to $2.1 billion (2009 dollars) for a 0.8-mile extension. A Green Line extension from Arlington saves you the bus loop and tunneling under Charles St, but not the trickiest parts of underpinning the structurally complex Boylston (flyover) and Chinatown (offset OL track on different elevations) stations, as well as the narrowness of Essex St that requires stacked platforms.

However, the general idea of connecting Kenmore to South Station and Seaport is absolutely a good point and warrants more discussions. And it's not hopeless if you avoid the Essex St corridor. Here's an idea I sketched a while ago:

Brown uses the existing bellmouth between Arlington and Boylston (former Public Garden portal) for a flying junction under Lime. It then turns onto Charles St and Stuart St to the Chinatown Gate vicinity, at which point you resume with the old GLR plans. Magenta uses the Charles St Connector idea (entirely isolated from Gold) to also turn onto Charles St, and then join Stuart St in a bi-level automatically-flying junction with Brown.

This allows you to run all four service combinations: Kenmore-Park (Lime), Kenmore-Seaport (Brown), Huntington-Park (Green), Huntington-Seaport (Magenta). (Note my coloring system is a bit different from Riverside's.)

It was initially motivated by my concerns of tunneling under Hudson St, a narrow street abutting tall buildings. While this alternative Stuart St alignment for Magenta alone may not be worth the hassle (namely utility relocation) compared to just "brute-forcing Hudson" or many other alternatives (which I plan on writing about at some point), the ability to run Brown is definitely another draw. Another benefit is that it does away with possible concerns regarding turnback capacity of the Park St loop.

The main concerns are:

• Reliability concerns of (1) having street-running branches enter the Seaport Transitway (instead of isolating them that GLR achieves), and (2) simply the amount of interlining required, with a new one now added at Seaport. (1) alone is today's Green Line which can hardly be described as reliable (see recent discussions), and (2) alone is NYC's entire subway system, where transit fans propose deinterlining every now and then. Neither alone is ideal, let alone both.
• Frequencies on individual lines. If you run 2-min headways (30 tph) on each trunk, this setup means you can only run 4-min headways for each color. It may not be too bad of a capacity downgrade, as the load is spread out between many transfer points (and the mainstream GLR proposal limits itself to 4-min on Green, Magenta and Gold anyway), but still something to keep in mind.

But yeah, you're right that GLR's proposed 3-seat ride between Seaport and the entire Kenmore division is definitely one of its biggest drawbacks from a route design perspective.

Edit: Damn! @Riverside beat me by 1 minute.

 

[Riverside]

Edit: Damn! @Riverside beat me by 1 minute.

L. O. L.

To be fair to you, you provided citations.

 

[BlazingZack]

Thank you both! This was very helpful and you are very welcoming!

Brown uses the existing bellmouth between Arlington and Boylston (former Public Garden portal) for a flying junction under Lime. It then turns onto Charles St and Stuart St to the Chinatown Gate vicinity, at which point you resume with the old GLR plans. Magenta uses the Charles St Connector idea (entirely isolated from Gold) to also turn onto Charles St, and then join Stuart St in a bi-level automatically-flying junction with Brown.

just to be sure, when you say old GLR plans, do you mean the Gold line? Or the Green line Stuart subway idea? Or something else?

 

[BlazingZack]

While I’m at it (I might as well ask all the tricky questions!), the thing that got me into MBTA transit ideas was the Urban Ring, which I’m still a fan of even though Ive seen it’s a bit divisive on this forum lol. My biggest question is has there been any general consensus or at least ideas on how the BU bridge wye works, and specifically how you get LRT from BU Bridge to Fenway (down park street) to ruggles. Personally, from when I’ve mapped it, I’m a fan of running it alongside (under or at grade) and then likely onto (at grade ofc) Mountfort street ideally mostly in its own ROW (alongside) or dedicated lanes, then just running dedicated lanes down park drive and then doing Riverside’s idea of pedestrianizing/dedicated transit way Fenway drive.

TL DR how do you get from the BU bridge wye to the other side of comm ave with LRT? Do you go over, under, or through?

 

[Riverside]

While I’m at it (I might as well ask all the tricky questions!), the thing that got me into MBTA transit ideas was the Urban Ring, which I’m still a fan of even though Ive seen it’s a bit divisive on this forum lol. My biggest question is has there been any general consensus or at least ideas on how the BU bridge wye works, and specifically how you get LRT from BU Bridge to Fenway (down park street) to ruggles. Personally, from when I’ve mapped it, I’m a fan of running it alongside (under or at grade) and then likely onto (at grade ofc) Mountfort street ideally mostly in its own ROW (alongside) or dedicated lanes, then just running dedicated lanes down park drive and then doing Riverside’s idea of pedestrianizing/dedicated transit way Fenway drive.

TL DR how do you get from the BU bridge wye to the other side of comm ave with LRT? Do you go over, under, or through?

A quick reply, but here is a broader overview of my take on this question, with the obligatory Pretty Map:

To your specific question of "is there a consensus on how to do this?", the answer to that is "Nope, definitely a topic of debate, and definitely no consensus yet!"

One question I think that would impact this: what kind of service are you running south of Fenway station? Is it surface-running in a dedicated ROW? In transit lanes? Is it grade separated? How far does it run -- LMA, Ruggles, Nubian? I think those would inform what kinds of investments and tradeoffs are reasonable between BU and Fenway.

 

[Longfellow]

@Riverside Very nice map, super interesting subject. If you don't mind me asking I'm curious what program you used. My thoughts...

• Comm ave subway is very attractive to me, but six tracks with BRT? Is this just to avoid interlining completely?
• BU could really use a less wide comm ave. The highest use of comm ave as designed is with a subway and a tree lined mall down the middle or on one side. If it was multiple tracks you could revive the A and take away the 57. They instantly get their campus back as well.
• Doubling back at kenmore over digging a new subway provides some really nice frequency to that b branch trunk (if only it were more dense) but it seems like it would probably add more than a few minutes to the trip?
• While it's a tight fit, if we were trying to go without or with only minor tunneling, Given that the pike may be decked there, there's room between mountfort st and the pike for some kind of crazy viaduct, or even move mountfort over the commuter rail tracks / take a row of brownstones and put the trains down Park drive. As long as we avoid dorms, we can and should be taking some land in brookline

Edited to add: Just saw the other guy mentioned Mountfort. I think there's merit all around but tunneling under the pike seems like it would be very deep grade-wise.

 

[BosMaineiac]

A quick reply, but here is a broader overview of my take on this question, with the obligatory Pretty Map:

View attachment 47445

To your specific question of "is there a consensus on how to do this?", the answer to that is "Nope, definitely a topic of debate, and definitely no consensus yet!"

One question I think that would impact this: what kind of service are you running south of Fenway station? Is it surface-running in a dedicated ROW? In transit lanes? Is it grade separated? How far does it run -- LMA, Ruggles, Nubian? I think those would inform what kinds of investments and tradeoffs are reasonable between BU and Fenway

Beautiful work, as always! Quick question: with the revival of the A branch, is the 57 necessary? I could see a short-turned bus pinging between Watertown and Oak Sq (if the A terminates at Oak), but would it really be necessary to have a surface transitway on Comm for it? Not saying it's a bad thing to have the redundancy. I could definitely see a similar treatment being useful on Huntington for the 39, unless of course the branch all the way to Arborway is revived.

 

[Teban54]

For my part, I've tried to address this in two ways. First, building a direct transfer between Copley and the new Gold Line platforms at Back Bay. This would be in the neighborhood of 800 feet, which is long, but IIRC is comparable to the Orange <> Blue transfers at State.

Agreed with the rest of the comment, but a small nitpick: Using OpenStreetMap's platform locations as estimates, the distance from the western edge of Blue Line's platforms to the northern edge of southbound Orange Line's platform is about 650 ft. (Another consideration with State is that it's asymmetric, so someone enduring this long transfer in one direction will only have to go through a much shorter 160' walkway on the return trip. That won't be the case for Copley-Back Bay.)

Thank you both! This was very helpful and you are very welcoming!

just to be sure, when you say old GLR plans, do you mean the Gold line? Or the Green line Stuart subway idea? Or something else?

I meant the Gold Line idea (as Riverside branded it), specifically the part connecting South Station to Bay Village, via the provision for Essex St hook-in and then Surface Rd (or more precisely, the parks immediately to its west).

Previously, the alignment south of there that we collectively settled on (or at least assumed) was to tunnel under Marginal Rd and Hudson St to Chinatown Gate. I called it "old" solely to contrast it with the alternative alignments I raised above that use Stuart-Kneeland from Bay Village.

While I’m at it (I might as well ask all the tricky questions!), the thing that got me into MBTA transit ideas was the Urban Ring, which I’m still a fan of even though Ive seen it’s a bit divisive on this forum lol.

To be clear, the "divisiveness" to me actually represents a much-needed, healthy debate, which I also learned a lot from personally and really appreciate them. (Special thanks to @TheRatmeister.)

And it makes sense, as Urban Ring is nowhere near as "settled" of a concept as GLR (even though the latter also has variables and uncertainties), and the sheer length of it with lack of ROW means it's guaranteed to have many, many alternatives. I think everyone is in agreement that Urban Ring(s) should be built, but a factor underpinning the discussions is really your proposed budget: How much are you willing to spend, how favorably do you view expensive infrastructure like TBM tunnels, what would be an acceptable service standard to you (BRT, streetcar LRT, 95% grade-separated "heavy metro" LRT, 100% grade-separated LRT, HRT; and whether running in mixed traffic is acceptable), etc. Obviously, different people will have different opinions on even just this matter, and that alone is already enough to fuel debates.

I'll note that this forum is often more conservative than average on the topics I mentioned, whereas places like r/mbta subreddit are much more optimistic than average (hence the $20 bil Urban Ring fantasy maps that float around there, and hence "bore baby bore" being the mantra there).

My biggest question is has there been any general consensus or at least ideas on how the BU bridge wye works, and specifically how you get LRT from BU Bridge to Fenway (down park street) to ruggles. Personally, from when I’ve mapped it, I’m a fan of running it alongside (under or at grade) and then likely onto (at grade ofc) Mountfort street ideally mostly in its own ROW (alongside) or dedicated lanes, then just running dedicated lanes down park drive and then doing Riverside’s idea of pedestrianizing/dedicated transit way Fenway drive.

TL DR how do you get from the BU bridge wye to the other side of comm ave with LRT? Do you go over, under, or through?

Absolutely no consensus at all. In fact, I'd argue this may be one of the trickiest and most variable parts of Urban Ring. Again, it heavily depends on your opinions on budget and service standards, and there are too many options to choose:

Almost any combination of lines here can give you an Urban Ring, and/or an alternative D-E connector that serves LMA more directly than the Huntington Ave stations.

Your choice depends on too many variables:

• a) How fast do you want trains to traverse through this quadrant?
  • At-grade LRT with mixed street running (most likely on Park Dr and Mountfort St)?
  • At-grade LRT with all 13 grade crossings, but with dedicated lanes only?
  • Grade separate as much as possible, with maybe 1-2 grade crossings?
  • Fully grade separated?
• b) Related to (a): How much demand is there for through-LMA rides and to-LMA rides from the north? This determines how many people benefit from a faster ride.
  • Example O-D pairs: Cambridge-LMA, OL North-LMA, Riverside-Kendall/Harvard, OL South-Kendall/Harvard, Nubian-Kendall/Harvard, many non-commute trips and trips involving B branch
• c) How much detour do you want to make to the southwest at LMA?
  • Which east-west road through LMA to use: Fenway-the-road, Longwood Ave, or Francis St?
  • Related to (b) in terms of how many riders will need to wind through the LMA detour
  • Also related to cost (financial and political), as Longwood Ave and Francis St will be more expensive
  • Note that street-running on Fenway-the-road may result in speed restrictions that offset advantages in travel time
• d) How much detour do you want to make to the northeast at Kenmore?
  • Several alignments too: Park-Mountfort, D-Pike, and "Kenmore/Lansdowne" (D-Lansdowne-Brookline Ave-B)
  • Again, see earlier note on travel times for street-running sections
• e) Related to (d): How important do you think Kenmore is?
  • Compare through-Kenmore and to-Kenmore demands
  • Hitting every GL branch may be as good as hitting Kenmore? IMO, its function as a bus transfer hub is overrated: the only Kenmore bus that doesn't go to LMA is the 57
  • Kenmore/Lansdowne does offer transfer to commuter rail, but some designs allow you to do it at West Station
  • 2015-17 passenger survey data: 42% of Kenmore riders start their trip from there, 27% transfer from buses, 31% transfer from another GL branch
    • 2022 passenger survey data is available, but sadly it drops the "Previous Mode" field and the raw number of passengers (only shows percentages), so not nearly as useful for this purpose
• (f) How important do you think getting to the core of LMA is?
  • Current D and E stations require average walk of 10 minutes to most hospitals, while a more central station can do much better
    • @Riverside has a more detailed table that he may want to post?
  • But LMA has higher transit mode share than most other employment centers, suggesting the 10-min walk may not be deterring too many people from using transit?
• (g) How important is a convenient transfer to the B branch?
• (h) Do you even want a continuous service at all?
  • One alternative is to simply terminate two legs of LRT services both at Brookline Village, avoiding the engineering challenges of cross-LMA altogether
  • Another is to have the northern half be LRT that ends at Brookline Village, and the southern half be BRT that goes through LMA surface roads, ending at Kenmore
  • Splitting the two services at Kenmore is also an option (if you can somehow short-turn Comm Ave trains)
  • Whether that's actually desirable depends on (b) and (e)
• (i) Of course: What's your budget?

I promise this list is not to scare you. If anything, it's Exhibit A of how much of the "divisiveness" really depends on your level of optimism. The "bore baby bore" Reddit folks will think very differently from someone like F-Line who questions just about any C&C subway with utility relocation, not to mention TBMs.

 

[Teban54]

Spoiler: My personal opinion on SW Urban Ring

First, I want to avoid a fully TBM'ed SW Urban Ring as much as possible. Both because of the absurd 2024 cost, and because I don't think it adds drastically greater value to cheaper proposals -- at the very least, it's a tradeoff.

But now is where I diverge from @Riverside: I'm somewhat pessimistic that a heavily street-running approach (dedicated transitway or not) will work well, either.

• The Green Line currently has additional speed restrictions anywhere it runs on the street. This Reddit comment claims it's 25 mph in dedicated medians, and 10 mph in mixed-running sections (outer E). That sounds like it will hurt travel time pretty significantly (though more analysis needed). Even if we remove all auto traffic, as long as sidewalks remain open (and I suspect the road may need to remain open to emergency vehicles), I'm not sure how much that will change.
• From Fenway-the-station to Huntington Ave, there are 10 intersections (not counting right-turn merges) along Fenway-the-road. 6 of them are signaled. That's too many grade crossings for my taste; at least 3 of them are with major roads (Riverway, Brookline Ave, Huntington Ave), and are likely not eliminable. Not to mention it cuts off the only access road to Emmanuel College.

(Compared to this, while Grand Junction's grade crossings bother me too, only 2 or arguably 1 of them are absolutely necessary (definitely Main St, possibly Mass Ave). All others seem eliminable with flyovers and/or duck-unders. It also doesn't run on a road, so you're less likely to run into speed restrictions.)

There's an aesthetic consideration as well (though not a very convincing one): It simply looks more "streetcar-y" than the kind of Urban Ring service we want to design and promote, which is decidedly more heavy-metro (GLX-like) than streetcar/tram (B/C branch-like). Many people out there already conflate these two types of services just because they both run LRT vehicles, and thus you get calls like "LRT Urban Ring is trash, HRT or bust". (Such philosophies play out for LRT vs. BRT, too.)

I do think the Fenway transitway idea is probably the best budget proposal for a through-LMA route. But this is a corridor where I'm personally more willing to spend more to get better service.

One idea I've been thinking of, and I think may be the most promising one: an Elevated above Fenway-the-road, starting from the D (west of Fenway-the-station), and descending into a tunnel east of Huntington Ave. I may elaborate on this later once I check feasibility.

As for north of Fenway-the-station, I'm tentatively still in favor of "Kenmore/Lansdowne" (the Eastern option in @Riverside 's post). But recently, I'm beginning to consider its drawbacks, particularly longer travel time due to the more roundabout route (more than twice as long as a Park-Mountfort alignment). For this reason, at one point I started considering "just brute-force a Park Dr tunnel", either as C&C with utility relocations, or in the worst case, TBM. However, I'm still brainstorming whether it's really worth it.

I am skeptical of surface-running solutions to the north of Fenway even more than to the south: both for the reasons already stated, and in particular, because the roads are too narrow. Park Dr north of Buswell St (and the entire Mountfort St) simply don't have room for bidirectional transit lanes, and that's an area with heavy traffic.

The most feasible idea I can come up with involves a pair of unidirectional streets:


Portions of Park Dr and St. Mary's St are converted to unidirectional for both cars and LRT (one lane for each). While this is feasible on paper, I remain concerned about its reliability and political feasibility. St. Mary's St is heavily residential, and while the street parking there looks like metered parking (thus more easily eliminated with enough political will), it's still a big challenge nevertheless -- it's Brookline. Its character also makes LRVs more likely to be stopped by random cars doing shenanigans on the street, or at crossings with Buswell St. Not to mention Mountfort St still lacks transit lanes, and you can only do that by buying air rights from BU (who plans to put academic buildings there themselves).

 

[Teban54]

• Doubling back at kenmore over digging a new subway provides some really nice frequency to that b branch trunk (if only it were more dense) but it seems like it would probably add more than a few minutes to the trip?

That was my concern as well. Compared to a Park-Mountfort subway, a Kenmore/Lansdowne subway adds 4-5 minutes of travel time (3.2 min while moving assuming 12 mph, and then making an extra stop with tight turns). It's the primary factor in making me question the alignment recently.

But the question is: What exactly are you comparing it to?

• Park-Mountfort subway is obviously the fastest.
• But Park-Mountfort surface is unlikely to be nearly as fast, both due to at-grade crossings and speed restrictions for running on the surface (as I mentioned earlier).
  • If we assume the surface-running segment achieves 8 mph (IIRC average travel speed on GL surface branches), the time savings from the route alone (without stops) gets reduced to 1.8 minutes, down from 3.2. At that point, there are definitely enough uncertainties with that route (not the least due to Mountfort mixed traffic) for the 1.8 mins to evaporate.
• Pike-D subway (Pink) saves 2.3 minutes from the route, down from 3.2 achieved by Park-Mountfort subway. Still saves about 3-4 minutes in practice factoring in the Kenmore stop, but slightly smaller difference.
• Both subways also involve their own engineering challenges (and political challenges of closing off part of the Pike for construction).
• Also consider that both these alternatives involve a less convenient transfer to the B branch and longer walk to BU campus, depending on how valuable that is. For those riders, there will be negligible time savings.

(Note: Any mention of "subway" above refers to any fully grade separated ROW, which can also be a viaduct.)

Spoiler: F-Line's earlier thoughts and official Urban Ring studies

Spoiler: F-Line's earlier thoughts and official Urban Ring studies
Here was a 2013 F-Line post in which he evaluated the Urban Ring MIS's two tunnel alignments, and then argued in favor of his "B-to-D boomerang" idea, which ironically sounds like a 2013 version of my Kenmore/Lansdowne.

Here's a 1997 version he explicitly referred to in his comment:

However, that's actually not the most recent. A 2001 study compared two tunnel corridors:

(Dotted green line is tunnel, solid line is at-grade. Also, shoutout to East Somerville, although this version achieves the same purpose at Lechmere. Boxes with a cross indicate grade crossings, and they mentioned it was for cost savings to offset the longer route and additional stations, which I find nonsense.)

They don't seem like the latest versions either, as Wikipedia has another one with a Harvard branch (though that seems to be BRT).

F-Line's poo-poo about Park Drive (in this and some other posts which I can't find) seems to be due to: (1) Utility relocations under Park Dr; (2) Digging under Muddy River (which is required for the 1997 alts, and the 2001 alts replace that with the equally-questionable Longwood Ave). Frankly, I'm not sure if I agree. (1) is a concern for tunneling pretty much anywhere, even with C&C, outside of the few selected corridors. While (2) is a practical concern, I would have thought his justification for BLX-to-Kenmore would have also applied to this case. (The BLX post actually explicitly mentions a short deep-bore section, so we can also do that if necessary.)

His arguments in favor of B-D via Kenmore were something I considered when drafting the Kenmore/Lansdowne proposal, but now I'm not sure how much I still stand by them. (Note that F-Line himself is no longer in favor of the B-D boomerang that goes through Kenmore GL station twice, either, but Kenmore/Lansdowne is more direct.)

• He assumes Kenmore is major enough of a node that there's tremendous value simply going through it. Over the years, I've increasingly felt this was not true: Kenmore's purpose as a transfer node is way overblown.
  • Its primary purpose was a split between the former-A (57), B, C and pre-bus-route-60 streetcars. But that's unnecessary if you can hit all these branches elsewhere.
  • The other buses that terminate at Kenmore all go to LMA. A subway that goes around LMA can obviously connect to them.
  • In summary, Kenmore's role as a bus/LRT hub is surprisingly limited, well below Nubian, Harvard and even Sullivan.
  • Kenmore may also have demand as a destination node, which I'm unsure of (needs further analysis). However, at the moment I don't see why it has to be necessarily worse than BU Central.
• He thinks BLX to Kenmore will help make it an anchor point with Urban Ring. But the same thing can be done at BU Central (not even necessarily with a less ideal transfer).
• He also thinks of interlining with the B and D as an advantage. This ties into my earlier thoughts on reliability -- at least, there are drawbacks for interlining with the B.

F-Line even thinks any of the tunnel alts above is $5 billion more expensive than B-to-D. That sounds... Way overblown to me. I'd guess even a new tunnel under Charles River won't cost that much.

 

[Teban54]

@Riverside Very nice map, super interesting subject. If you don't mind me asking I'm curious what program you used. My thoughts...

• Comm ave subway is very attractive to me, but six tracks with BRT? Is this just to avoid interlining completely?

In @Riverside's proposal, the two Blue Line tracks are obviously needed regardless. The 4 tracks between the B (and possibly A) branch and the Urban Ring (from both Kendall and Harvard) are indeed to avoid interlining. Given there are two routes running on each, having all four interline will exactly max out the capacity; and the A/B branches involve heavy street-running further west, creating reliability concerns and propagating those delays onto Urban Ring (which itself faces its own street-running on Fenway-the-road).

The quad-track setup will be needed at two ends regardless to create flying junctions. IIRC, I've seen people saying the additional cost of digging a C&C quad-track subway compared to a two-track subway is relatively smaller (compared to TBM), but I don't have a citation for that. But one possible concern is utility relocation: the appeal of burying the B (and E) is that little or no utilities exist beneath the LRT reservation, but that's less certain under the travel lanes.

• BU could really use a less wide comm ave. The highest use of comm ave as designed is with a subway and a tree lined mall down the middle or on one side. If it was multiple tracks you could revive the A and take away the 57. They instantly get their campus back as well.

Beautiful work, as always! Quick question: with the revival of the A branch, is the 57 necessary? I could see a short-turned bus pinging between Watertown and Oak Sq (if the A terminates at Oak), but would it really be necessary to have a surface transitway on Comm for it?

Riverside and F-Line are both of the opinion that a resurrected A branch should only go as far as Oak Square, and I agree.

• The biggest reason is again reliability. Oak Square to BU Bridge already has 3.1 miles of street running (only 0.3 miles shorter than the B would be once BU Central is buried). Running to Watertown Yard adds another 1.5 miles, and involved tricky traffic conditions when crossing the Pike, at which point it really becomes too long for me. Remember, the old A branch was chosen to be terminated (when the D was launched and there was a shortage of cars) exactly because it was the least reliable and had too much street running.
• Demand patterns on the 57 also support it. Bus route profile for the 57 shows that while many people board at Watertown Yard and some at Newton Corner, the remaining stops along Tremont St and Galem St are relatively light until the bus hits Oak Square. It's not clear to me whether the Watertown and Newton Corner riders are taking it all the way to Kenmore and downtown, but even if they were, there may be better solutions for them (e.g. improving 504 and making it cheaper, commuter rail Newton Corner infill, improving 70 and 71 for Watertown).
• The roads may just be too narrow for dedicated transit lanes. Parts of the A's route east of Oak Square already concern me, where the road is often 46' wide and not enough to accommodate 4 vehicle lanes and 2 bike lanes. (I assume F-Line's A branch proposal may have been before dedicated bike lanes.) But it gets even worse on Tremont St further west, where it's often just 43' wide. (To be fair, that portion also doesn't have dedicated bike lanes which may make it easier, but there's no reason to believe it won't ever get bike lanes; the neighborhood also seems lower density and more car-dependent, so getting rid of parking will be a hard sell.)

If the A only goes to Oak Square, the need for the 57 bus obviously remains.

(Edit: I realized I completely missed the part of @BosMaineiac 's question about shortening the 57 to Watertown-Oak Sq, vs. Running it full-length to Kenmore. But I think it's not clear either, because I suspect there's a decent demand from Watertown/Newton Corner to east of Oak Square, such as Brighton, Allston and BU. A forced transfer isn't ideal. But yeah, definitely worth the discussion. )

• While it's a tight fit, if we were trying to go without or with only minor tunneling, Given that the pike may be decked there, there's room between mountfort st and the pike for some kind of crazy viaduct, or even move mountfort over the commuter rail tracks / take a row of brownstones and put the trains down Park drive. As long as we avoid dorms, we can and should be taking some land in brookline

Edited to add: Just saw the other guy mentioned Mountfort. I think there's merit all around but tunneling under the pike seems like it would be very deep grade-wise.

I've considered a viaduct over Park Dr too -- using exactly the land between Mountfort and Worcester Line as you suggested. The challenges are:

• Putting up an El next to Brookline neighborhoods next to Mountfort St: Good luck with NIMBYs. (The buildings next to Mountfort and most buildings on both sides of Park Dr are owned by BU, but a few Park Dr buildings at the corners are private.)
• BU air rights, as they're definitely looking into putting buildings on the parcels next to Mountfort.
• Space: You have 950' of slack between BU Bridge and the point where the greenspace becomes too narrow (meaning you need to be above Mountfort by that point).
  • Using @Riverside's rule-of-thumb of "260 ft per level", it's enough to climb the 3 levels required (below Pike - Pike - Mountfort - above Mountfort), but with little slack.
  • But another problem is Carlton St: You have to be at Pike level (or below) at that point. There's only 410' between that and where you need to be above Mountfort, and you need to climb up 2 levels, which sounds infeasible.