Green Line Reconfiguration

[Riverside]

That's true, but skipping this would also mean all North Station-Nubian or Medford-Nubian passengers have to transfer at Park St now. Given that Boylston is the least used central subway station, perhaps that should be viewed as an opportunity to have a higher quality transfer at a less busy station. Park St is already insanely busy and adding even more Gov Center & North - Copley & West transfers could be quite bad. From there you would be looking at a full Park St rebuild and then costs are really going to skyrocket.

But I think this ultimately gets at the question of: Is this even a worthwhile goal? Is Medford/Newton/Needham/Seaport traffic really enough to justify platform lengthening across the network? As I mentioned previously 5 minute headways with 2-car Type 10s already quadruples capacity on the Washington St route, for example. Would the extra 50% bump:

1. Justify the costs
2. Make sense to put towards the GL in the first place? There's plenty of platforms that would need to be lengthened at pretty significant cost. Given that an orbital route would take load off radial routes, would that money be better spent as a nice down payment on a new orbital line?

While the ridership statistics did give me a curious idea of consolidating Boylston and Arlington into an in-between station at the site of the former portal between Arlington St and Charles St (provisioned for Post Office Sq), as for closing Boylston itself, I agree with @TheRatmeister's conclusions: Ironically, while consolidating Boylston may have value in today's Green Line, it likely becomes much less desirable in a full GLR world.

With B and C cut back to Park St, the transfer possibilities actually increase at Boylston and Park St: In addition to transfers to the Red Line (don't forget additional passengers from Nubian), now they will also need to handle transfers between the Kenmore system (my Lime, your Green) and the Bay Village system (my Green/Gold, your Gold). Opposite-direction transfers have to go to Park St regardless, but Boylston can help alleviate same-directions transfers, which I feel will be more common than opposite transfers - particularly from A/B/C to Government Center, North Station*, etc.

Okay yeah, this is a reasonable counterargument that has changed my mind.

Demand for 3-car Type 10s on the GLR, assuming it's feasible?

If we assume feasibility is not a question, I actually feel there will almost certainly be demand for 3-car Type 10s on the core GLR routes: my Green (North Station-LMA) and Magenta (Seaport-South Station-LMA) Lines.

From a super quick overview it seems like some other problem points would/could be:

• Science Park, as you said
• Haymarket
• Gov Center NB
• Prudential
• Symphony
• Riverside
• Reservoir
• Medford/Tufts

Plus some smaller works for the other GLX stations and some other D branch stops like Newton Centre for example.

Unfortunately, I think that the Silver Line Seaport stations will also present limitations here -- I just did a quick check and I think that, for example, Courthouse is in the neighborhood of 200' -- which poses a challenge even for 2-car supertrains, to say nothing of 3-car hypertrains.

(I had originally been going to suggest running supertrains on the North Station-LMA service and hypertrains on the Seaport-LMA service, but obviously that wouldn't work if the Seaport stations are too close.)

So, a target of 225' may be what we have to live with.

 

[Riverside]

In this 2016 post (below) F-line notes that it would be operationally dangerous to keep the bus turnaround loop under Atlantic Ave and a Greenline portal on Atlantic. He noted a portal is possible but the bus loop would need to be removed (and he felt that was not realistic).
http://archboston.com/community/threads/crazy-transit-pitches.3664/post-254062

I need to read through more of his points about tunneling, but FWIW I no longer agree with his analysis that the bus loop is a must-have. There are multiple other options for both SL1 and SL3.

 

[Teban54]

Here's my submission to the Transportation Dreams cartography challenge: A fantasy map dedicated to the Green Line Reconfiguration.

The image below has been compressed due to ArchBoston's limits on display of images. A version with higher resolution can be found here: View attachment 45838

I also want to use this opportunity to thank everyone on this forum who has contributed to the idea of Green Line Configuration over the almost 10 years. I truly feel it's one of the best transit proposals in Boston that I've seen, and yet the idea is so poorly known to the outside world, compared to analogous projects like NSRL and Urban Ring. That's why I made the map in the first place, as an effort to raise public awareness.

View attachment 45840

Following up on my GLR map: Somewhat surprisingly, a Redditor came to the post today and left a long, thoughtful comment with several interesting ideas. I ended up writing 7 (!!) long comments there in response.

While not all of their comments got my agreement (I ended up spending significant effort justifying the intuitions behind GLR in the first place), and there are several ideas there that are likely infeasible or that I am strongly against (Essex St, F to Mattapan, A via Grand Junction, etc), I do think it's important to have this outsider perspective. A lot of components, ideas and underlying principles that we on archBoston have taken for granted may not be obvious to someone else, and conversations like this give us opportunities to inspect them more closely or even challenge them.

Some of their really intriguing ideas include: (Again, this doesn't necessarily mean agreement, but worth thinking about)

• A "first gen" build of Needham branch as an extension of the C branch past Cleveland Circle
• BLX to Back Bay via Arlington (the station, not the city)
• Surface extension of Seaport Transitway routes (M/N) from Silver Line Way to South Boston
  • Though, this was the old SL3 that got discontinued due to poor ridership
• An additional faucet for the Central Subway (my Lime Line) to Seaport
  • They proposed it via Essex, which is exactly like Riverside's 2021 proposal that got shut down due to Essex's unviability

 

[Riverside]

a Redditor came to the post today and left a long, thoughtful comment with several interesting ideas. I ended up writing 7 (!!) long comments there in response.

That is a shockingly productive Reddit exchange. (Do I bag on Reddit too much? Nah, probably not.)

A "first gen" build of Needham branch as an extension of the C branch past Cleveland Circle

I think you explained this pretty well, but I really see it as a non-starter for lots of reasons. Not of the least of which is that all of the switches point the wrong way:

BLX to Back Bay via Arlington (the station, not the city)

This is not unheard-of in these kinds of discussions. IIRC, this is similar to something @vanshnookenraggen sketched out several years ago. It certainly could be interesting to extend it to Back Bay and then somehow use the Mass Pike alignment to make it out to the Kenmore area. The route becomes a bit roundabout but that might not be the end of the world.

Surface extension of Seaport Transitway routes (M/N) from Silver Line Way to South Boston

• Though, this was the old SL3 that got discontinued due to poor ridership

Always worth reconsidering, though I tend to think this alignment runs the "wrong way" -- a through-run LRT line in the Seaport would continue on to Back Bay, and Southie residents already have a couple of bus routes that provide that connection (and are able to serve the eastern half of Southie which would be much harder to serve from the Transitway). But yes, resurrecting a branch to City Point isn't itself a terrible idea, I just think it's not an amazing one either.

An additional faucet for the Central Subway (my Lime Line) to Seaport

• They proposed it via Essex, which is exactly like Riverside's 2021 proposal that got shut down due to Essex's unviability

Yeah, nothing more to add here.

 

[Teban54]

I think you explained this pretty well, but I really see it as a non-starter for lots of reasons. Not of the least of which is that all of the switches point the wrong way:
View attachment 47005

LOL! I didn't even check the track map when writing that comment. Yeah, given that and the apparent infeasibility of merging C and D anywhere (not at Reservoir station, not further west, and not further east)... Needham-via-C is out.

At least Needham-via-surface-E is actually doable.

• (Edit: One thing the discussion made me appreciate more is the value of a D-E surface connector, as "Phase 1" for implementing Needham service if other infrastructure have not been built yet (most notably the Back Bay-Bay Village subway). This way, Riverside trains still run via Fenway, and Needham trains run via LMA surface, largely replacing E branch service. Heath St (and possibly Hyde Square) has several possible solutions:
  • Share the E branch's tph between Heath St and Needham, with a heavier weight towards Needham (e.g. instead of 8 tph to Heath St as scheduled today, there would be 5 tph to Needham and 3 tph to Heath St)
    • Or, add some of D branch's tph into the mix
  • Run Heath St trains as a shuttle to Brigham/MFA/etc, with transfers to the Needham-downtown branch
  • Build the D-E surface connector with a complete wye, such that Heath St trains can run to Longwood and Fenway, and then short-turn at Kenmore

This is not unheard-of in these kinds of discussions. IIRC, this is similar to something @vanshnookenraggen sketched out several years ago. It certainly could be interesting to extend it to Back Bay and then somehow use the Mass Pike alignment to make it out to the Kenmore area. The route becomes a bit roundabout but that might not be the end of the world.

A good thing with that proposal is that it offers another direct connection to Back Bay, this time benefitting Blue Line residents in East Boston and beyond.

However, the BL-BBY connection is not nearly as desperately needed as a lot of other things. One reason is that Blue Line's catchment areas (East Boston, Orient Heights etc) already see Back Bay as one of the major travel demand nodes within downtown, likely due to the relatively convenient transfer to GL and OL and straighter route (unlike from, say, Cambridge). A direct connection to Back Bay on top of that is likely not worth the high cost of tunneling through downtown.

(It also benefits wherever BL gets extended to further west, but the same discussion applies, this time with a possibly even more convenient transfer at Kenmore.)

 

[TheRatmeister]

I think you explained this pretty well, but I really see it as a non-starter for lots of reasons. Not of the least of which is that all of the switches point the wrong way:

So this obviously wouldn't be as easy as just running the trains, as you pointed out, but maybe it's still worth doing. It seems like it might be possible to add a track connection to the C branch along Strathmore Rd (At the expense of the mysterious building at 26 Strathmore, but it's state owned already so no property acquisitions necessary) In addition to potential Needham services this would mean that in the event of any problems or closures between Reservoir and Kenmore, D branch trains could instead travel via the C Branch, potentially lessening the impact and need for shuttle services. Again, kind of a crazy transit pitch but I don't think it's worth immediately shutting down.

 

[Riverside]

So this obviously wouldn't be as easy as just running the trains, as you pointed out, but maybe it's still worth doing. It seems like it might be possible to add a track connection to the C branch along Strathmore Rd (At the expense of the mysterious building at 26 Strathmore, but it's state owned already so no property acquisitions necessary) In addition to potential Needham services this would mean that in the event of any problems or closures between Reservoir and Kenmore, D branch trains could instead travel via the C Branch, potentially lessening the impact and need for shuttle services. Again, kind of a crazy transit pitch but I don't think it's worth immediately shutting down.

Yeah, I could be on-board with building such a connection for operational service, I just wouldn’t want to run a regular load-bearing revenue service on it.

I think I’ve said this before, but even without a D-E connector, I think a Needham starter service could be viable by splitting existing Riverside frequencies, and supplementing with short-turns at Kenmore — particularly if this happens while a truncated CR line is still running to NJ or Hersey for a short while before OLX kicks in, reducing demand on Green slightly.

It would not be a long-term solution, but I think it can be viable enough to provide flexibility to the build order.

(@Teban54, replying to you later today, fingers crossed.)

 

[TheRatmeister]

Yeah, I could be on-board with building such a connection for operational service, I just wouldn’t want to run a regular load-bearing revenue service on it.

I think it depends on how you build it. If nothing else about Strathmore changes, yeah I wouldn't want to use that for regular service unless it's absolutely necessary. But Strathmore currently operates as a one way loop, with traffic going in on Strathmore and going out on Clinton Path. What if:

1. The CVS parking lot is reduced in size to allow for a connection to the parking area for 1885-1925 Beacon St
2. Clinton Path is made two-way
3. Strathmore Rd between Beacon St and Reservoir Yard is closed to all car traffic and converted into a transitway (Complete with green track.) Sidewalks get to stay.
4. A transit-priority light is added at the new intersection.

At that point you have something higher quality than existing infrastructure like the Packards Corner intersection, I don't see why it couldn't be used for revenue service.

There is also another future problem: Cleveland Circle isn't big enough for 2-car type 10s and will need to be rebuilt at some point. Even without any Needham Service, it seems like keeping it would be hard to justify given that Reservoir already has 2 side platforms that are already long enough (Or at minimum can be extended with much less effort) and can be used for terminating service.

 

[737900er]

Tangentially related, but does anyone know the purpose of this track? I've neve seen it used for anything.

 

[Riverside]

I think it depends on how you build it. If nothing else about Strathmore changes, yeah I wouldn't want to use that for regular service unless it's absolutely necessary. But Strathmore currently operates as a one way loop, with traffic going in on Strathmore and going out on Clinton Path. What if:

1. The CVS parking lot is reduced in size to allow for a connection to the parking area for 1885-1925 Beacon St
2. Clinton Path is made two-way
3. Strathmore Rd between Beacon St and Reservoir Yard is closed to all car traffic and converted into a transitway (Complete with green track.) Sidewalks get to stay.
4. A transit-priority light is added at the new intersection.

At that point you have something higher quality than existing infrastructure like the Packards Corner intersection, I don't see why it couldn't be used for revenue service.

There is also another future problem: Cleveland Circle isn't big enough for 2-car type 10s and will need to be rebuilt at some point. Even without any Needham Service, it seems like keeping it would be hard to justify given that Reservoir already has 2 side platforms that are already long enough (Or at minimum can be extended with much less effort) and can be used for terminating service.

To be clear, my objection is to a suburban service needing to run via a surface line making stops every couple of blocks. If, for example, an express track could be built along Beacon, then I think that makes the idea more competitive. But the idea of rerouting C trains into the Reservoir side platforms is interesting. I think you'd need to make pretty significant modifications to the yard to enable access back to Strathmore as you propose, and I think the existing station location could be maintained by eliminating these yard access tracks and converting and lengthening the platforms into a center platform. (And converting the crossover at Ayr Road into a full X.)

 

[Teban54]

I think it depends on how you build it. If nothing else about Strathmore changes, yeah I wouldn't want to use that for regular service unless it's absolutely necessary. But Strathmore currently operates as a one way loop, with traffic going in on Strathmore and going out on Clinton Path. What if:

1. The CVS parking lot is reduced in size to allow for a connection to the parking area for 1885-1925 Beacon St
2. Clinton Path is made two-way
3. Strathmore Rd between Beacon St and Reservoir Yard is closed to all car traffic and converted into a transitway (Complete with green track.) Sidewalks get to stay.
4. A transit-priority light is added at the new intersection.

At that point you have something higher quality than existing infrastructure like the Packards Corner intersection, I don't see why it couldn't be used for revenue service.

There is also another future problem: Cleveland Circle isn't big enough for 2-car type 10s and will need to be rebuilt at some point. Even without any Needham Service, it seems like keeping it would be hard to justify given that Reservoir already has 2 side platforms that are already long enough (Or at minimum can be extended with much less effort) and can be used for terminating service.

D-C connector engineering challenges

My biggest concern isn't even with the current layout of Strathmore: it's with the Reservoir Carhouse.

The Strathmore alignment basically cuts the carhouse in half. Not only do parts of the tracks circled in red permanently lose the ability to store trains, but there will be heavy interference with accessing the storage tracks further east. If regular service of just a single branch is activated, trains will pass through the yard every 4 minutes, which I think will severely compromise yard operations. Signals may also be an issue, given the junction is already maximally complex both on the yard's side and on the D's side with 5 tracks. (Not to mention possible concerns with having passengers onboard through the yard.)

At a time when even the existing Green Line system is in need of more storage capacity due to Type 10s, that's probably not the direction we want to go.

All this is before even considering the need to demolish the building! Even without any property rights issues, there are still costs (both financially and socially).

If you really want to build it, you're almost better off moving further east to Dean Rd, and trying to build a spur that elevates from the Highland Branch and lands onto the road's level. At least there's only a playground here (though, given the playground is owned by Brookline, there may be NIMBY issues).

Which brings us to the question of... All this concrete, for what?

There are several different objectives that different people may imply here:

1. As a non-regular service connection for improving resiliency (e.g. shutdowns)
2. As a temporary route to enable Needham service until GLR is built more substantially
3. As a permanent route for Needham to avoid doing GLR altogether

To me, its uses stop at (1). There are many different ways to achieve (2) with or without a D-E surface connector, as extensively discussed, so a D-C connector isn't even near the top of the list of alternatives. As for (3)... Let's just say that reducing the entire GL Reconfiguration concept to "enabling Needham service" is just wrong.

The engineering challenges and costs required for the D-C connector seem to far outweight the benefits from (1), maybe even (1+2). And that's before we get to the operational considerations of mixing Needham with 2.5 miles of street-running via the C, which @Riverside pointed out (and I agree with). (The C takes 14 stops from Cleveland Circle to Kenmore, and 14 stops on the D gets you to Haymarket.) Plus, the demand patterns: Needham riders will likely have a much greater need for the Huntington-LMA corridor than the Beacon St corridor (N-via-C all but ensures nobody from Newton Highlands onwards will take the N, whereas N-via-E will get some riders there).

There is also another future problem: Cleveland Circle isn't big enough for 2-car type 10s and will need to be rebuilt at some point. Even without any Needham Service, it seems like keeping it would be hard to justify given that Reservoir already has 2 side platforms that are already long enough (Or at minimum can be extended with much less effort) and can be used for terminating service.

There are many other solutions to this problem. Removing the yard leads facing Beacon St (as mentioned) is one; closing the Ayr Rd intersection is another. (Edit: You can also move the entire station to the east between Ayr and Strathmore without reconfiguring intersections.)

Also, if we close Cleveland Circle completely, what happens when GLR is built? Reservoir isn't ideal as a terminal, and turning the C on the D's tracks sounds like an operational disaster. Unless the answer is to permanently run Needham-via-C, which itself seems problematic.

 

[737900er]

To lengthen the platform at Cleveland Circle the Ayr Road crossing should be closed.

If you're doing A-branch reactivation, extending the C to Lake Street is probably a more reasonable pitch, especially if there would be reduced frequencies west of Packards Corner. Reconfiguring Reservoir, especially with the grades involved, would be challenging. Interlining Beacon and Highland services is against one of the core tenets of your GLR: keeping the legacy streetcar and modern LRT systems as separate as possible.

 

[Riverside]

Tangentially related, but does anyone know the purpose of this track? I've neve seen it used for anything.
View attachment 47015

I'm completely guessing here, but I wonder if it is helpful for flexibility during staging movements, especially if there's a bit of a pile-up. A train on the extra platform can merge onto the main line eastbound while another train holds on the side track, leaving space for another train to sit at the primary inbound platform .

Or it might just be a helpful place to shove an out-of-service set to get it off the main line while they figure out how to get it into the yard. Only so many places where you can fit a track like that, so take it where you can get it?

 

[TheRatmeister]

The Strathmore alignment basically cuts the carhouse in half. Not only do parts of the tracks circled in red permanently lose the ability to store trains, but there will be heavy interference with accessing the storage tracks further east. If regular service of just a single branch is activated, trains will pass through the yard every 4 minutes, which I think will severely compromise yard operations. Signals may also be an issue, given the junction is already maximally complex both on the yard's side and on the D's side with 5 tracks. (Not to mention possible concerns with having passengers onboard through the yard.)

At a time when even the existing Green Line system is in need of more storage capacity due to Type 10s, that's probably not the direction we want to go.

While I don't think either of us have the data to prove it, I'd suspect that the yard space costs are probably lower than you're imagining. Not zero, but I don't think they'd be severe enough to immediately be a dealbreaker. The other consideration is that, as you said, yard space is short and we need to build more. And if we're building a new yard, the cost of having it be able to take 35 trains instead of 30 trains for example is rather low.

As a temporary route to enable Needham service until GLR is built more substantially

As much as we might like it to be that way, any version of GLR would have several different phases and parts, each with their own timelines and inevitable delays. The more these parts can be independent from each other, such as Needham Service starting before a Huntington Ave Subway is done for example, the better.

Also, if we close Cleveland Circle completely, what happens when GLR is built? Reservoir isn't ideal as a terminal

It's no worse than Riverside, Medford/Tufts, or Union Sq. It's not like termini need loops unless we're planning on converting the GL to one-sided trolleys.


All that being said, a part I think we've both overlooked is the elevation change Strathmore/Reservoir Carhouse and the GL-D tracks that would require an engineering solution of some form, and that would absolutely kill this version of the proposal. Perhaps a route along Clinton Path could work since the elevation difference there is much smaller, but this would require either a flat junction where the split is or quad-tracking between Reservoir Station and the split. The former would not be the worst operationally but it certainly wouldn't be great for terminating services, and the latter would take up way more yard space than the Strathmore route and would certainly cause problems in that regard. The flat junction option may be worth considering for the operations benefits, depending on the costs, but for regular operation the choice between the flat junction or major axing of yard space is a pretty big problem.

 

[Riverside]

(Edit: One thing the discussion made me appreciate more is the value of a D-E surface connector, as "Phase 1" for implementing Needham service if other infrastructure have not been built yet (most notably the Back Bay-Bay Village subway). This way, Riverside trains still run via Fenway, and Needham trains run via LMA surface, largely replacing E branch service

Yes, this has been my thinking for a long time, though it gets dicey with the stretch of mixed street-running and the slower runtime via Huntington -- 14 min via Kenmore vs 18 min from Riverway, or even 13 min from just Brigham Circle.

Probably I would mitigate this by splitting Needham trains between Kenmore and Huntington, so that there is a speedier option available while still maintaining higher frequencies to Needham. There would also be some improved access to LMA, so there's some consolation.

You can also probably mitigate this in part by adding full transit lanes on Huntington/Route 9 all the way to Brookline Village. Even with a future underground connection, transit lanes would remain useful (if not vital) for 39 service.

Heath St (and possibly Hyde Square) has several possible solutions:

1. Share the E branch's tph between Heath St and Needham, with a heavier weight towards Needham (e.g. instead of 8 tph to Heath St as scheduled today, there would be 5 tph to Needham and 3 tph to Heath St)
   • Or, add some of D branch's tph into the mix
2. Run Heath St trains as a shuttle to Brigham/MFA/etc, with transfers to the Needham-downtown branch
3. Build the D-E surface connector with a complete wye, such that Heath St trains can run to Longwood and Fenway, and then short-turn at Kenmore

Option 1 is what I'd do initially. Option 2 seems like an easy target for eventual bustitution. Option 3 is a more expensive build and would depend in part on how an eventual D-E subway connector is built, but is definitely a reasonable idea. (If our northside Urban Ring service -- my Bronze Line on my map -- is terminating at Brookline Village, you could make an argument to just extend that to Heath and maybe Hyde Sq. That would actually follow the same general patten as the original proposal for the T39.)

The more these parts can be independent from each other, such as Needham Service starting before a Huntington Ave Subway is done for example, the better.

Agreed, but as mentioned above, a surface D-E connector would still provide value even without the subway. I do actually think they are largely independent.

 

[ulrichomega]

D-C connector engineering challenges

My biggest concern isn't even with the current layout of Strathmore: it's with the Reservoir Carhouse.

The Strathmore alignment basically cuts the carhouse in half. Not only do parts of the tracks circled in red permanently lose the ability to store trains, but there will be heavy interference with accessing the storage tracks further east. If regular service of just a single branch is activated, trains will pass through the yard every 4 minutes, which I think will severely compromise yard operations. Signals may also be an issue, given the junction is already maximally complex both on the yard's side and on the D's side with 5 tracks. (Not to mention possible concerns with having passengers onboard through the yard.)

At a time when even the existing Green Line system is in need of more storage capacity due to Type 10s, that's probably not the direction we want to go.
View attachment 47020

All this is before even considering the need to demolish the building! Even without any property rights issues, there are still costs (both financially and socially).

If you really want to build it, you're almost better off moving further east to Dean Rd, and trying to build a spur that elevates from the Highland Branch and lands onto the road's level. At least there's only a playground here (though, given the playground is owned by Brookline, there may be NIMBY issues).
View attachment 47021

Which brings us to the question of... All this concrete, for what?

There are several different objectives that different people may imply here:

1. As a non-regular service connection for improving resiliency (e.g. shutdowns)
2. As a temporary route to enable Needham service until GLR is built more substantially
3. As a permanent route for Needham to avoid doing GLR altogether

To me, its uses stop at (1). There are many different ways to achieve (2) with or without a D-E surface connector, as extensively discussed, so a D-C connector isn't even near the top of the list of alternatives. As for (3)... Let's just say that reducing the entire GL Reconfiguration concept to "enabling Needham service" is just wrong.

The engineering challenges and costs required for the D-C connector seem to far outweight the benefits from (1), maybe even (1+2). And that's before we get to the operational considerations of mixing Needham with 2.5 miles of street-running via the C, which @Riverside pointed out (and I agree with). (The C takes 14 stops from Cleveland Circle to Kenmore, and 14 stops on the D gets you to Haymarket.) Plus, the demand patterns: Needham riders will likely have a much greater need for the Huntington-LMA corridor than the Beacon St corridor (N-via-C all but ensures nobody from Newton Highlands onwards will take the N, whereas N-via-E will get some riders there).


There are many other solutions to this problem. Removing the yard leads facing Beacon St (as mentioned) is one; closing the Ayr Rd intersection is another. (Edit: You can also move the entire station to the east between Ayr and Strathmore without reconfiguring intersections.)

Also, if we close Cleveland Circle completely, what happens when GLR is built? Reservoir isn't ideal as a terminal, and turning the C on the D's tracks sounds like an operational disaster. Unless the answer is to permanently run Needham-via-C, which itself seems problematic.

I'm so sorry, but I can't get this image out of my head. Please don't consider it a serious proposal.

 

[Teban54]

All that being said, a part I think we've both overlooked is the elevation change Strathmore/Reservoir Carhouse and the GL-D tracks that would require an engineering solution of some form, and that would absolutely kill this version of the proposal.

Good call, can't believe I forgot to check the 3D maps. Yeah, the elevation difference definitely kills Strathmore.

Perhaps a route along Clinton Path could work since the elevation difference there is much smaller, but this would require either a flat junction where the split is or quad-tracking between Reservoir Station and the split. The former would not be the worst operationally but it certainly wouldn't be great for terminating services, and the latter would take up way more yard space than the Strathmore route and would certainly cause problems in that regard. The flat junction option may be worth considering for the operations benefits, depending on the costs, but for regular operation the choice between the flat junction or major axing of yard space is a pretty big problem.

Wait, I though you were proposing a flat junction all along... To me, it didn't look like there would even be space for a flying junction at Strathmore.

Regardless, I think a flat junction is potentially fine for this if that ends up being what's feasible. The traffic level expected at such a junction will be half of Copley's (2 branches vs. 4), and the main dealbreaker - -an inbound N train arriving at the same time as an outbound D train -- only occurs if the inbound N arrives at the start of a 7.5-min window (interval between outbound D trains), instead of a 2.5-min window at Copley. It also gets into the question of how much we want to spend on this connector (elaborated below).

On the other hand, Dean Rd looks like it actually has space for a flying junction without even involving the park. Build a pair of highway-like ramps that ascend to street level, like below. The main drawback is eliminating Englewood Ave station (though that can be interpreted as a feature).

But I think this is where we get to the question of: How much do we want to spend on a D-C connector?

• Any flying junction will obviously involve more concrete.
• If a surface connector of any kind is built, I still favor a D-E connector. As @Riverside and I said, it achieves basically the same purpose as D-C (temporary service to Needham before GLR is built in full), gives a more straightforward route with shorter street-running, and serves a corridor that appears more attractive to Needham and Newton residents.
• More importantly: I think any kind of concrete, especially on D-C, risks becoming an excuse to not build GLR properly. The greater the initial cost, the higher the risk. (At least infrastructure for a D-E connector has possibility of being reused, and more importantly, signaling the right direction for the long term.)

Spoiler: Terminal operations

It's no worse than Riverside, Medford/Tufts, or Union Sq. It's not like termini need loops unless we're planning on converting the GL to one-sided trolleys.

When I wrote that comment, my expectation was that the D-C connector will land on the D's through-running tracks and use the D's Reservoir platforms. If that's the case, and if you want the C to terminate at the D's platforms at Reservoir (assuming the N runs via Huntington subway), that presents major differences from Riverside, Medford/Tufts and Union Square: it turns back using the same tracks that another route runs through. An inbound D can't enter Reservoir until a terminating C on that platform has left.

Having said that, I do notice there's a spur to the north with shorter platforms that connect directly to Chestnut Hill Ave, and the platforms seem just long enough to be modified for 2-car Type 10s (228', see below). So in such a world, terminating C trains can use that; although it will still interline with the D and N, which may make it infeasible or at least undesirable anyway.

This also got me wondering: If there's demand for a more convenient C-D transfer -- especially if/when the D and N are rerouted to Huntington, South Station and Seaport, opening up several transfer possibilities -- would it be feasible to extend the C from Cleveland Circle to Reservoir, coming in from the west? Like this:

Spoiler: A time in history when D-via-C was a thing

From Wikipedia:

In 1974, the MBTA began rebuilding the line to accommodate the new Boeing LRVs. From June 8 to September 11, Highland branch cars ran on Beacon Street from Reservoir to Kenmore. A temporary inbound-to-outbound turning loop was built east of Reservoir for the diversion. Inbound cars stopped at Reservoir, ran around the temporary loop, and up the outbound side of the regular loop towards Cleveland Circle. Outbound cars via Beacon Street ran down the inbound side of the regular loop, around the same temporary loop track, and then continued outbound from the station.[9]

The regular short-turn loop was closed in August 1980 as part of the closure of the old Reservoir Carhouse, which had been built in 1889 when the Beacon Street line opened.[9][11] The old carhouse closed on June 25, 1982; a new building opened the next year.[9]

This is pretty interesting. However, I don't see any traces of that loop anymore.

 

[Teban54]

Time considerations of Needham surface running

Yes, this has been my thinking for a long time, though it gets dicey with the stretch of mixed street-running and the slower runtime via Huntington -- 14 min via Kenmore vs 18 min from Riverway, or even 13 min from just Brigham Circle.

Probably I would mitigate this by splitting Needham trains between Kenmore and Huntington, so that there is a speedier option available while still maintaining higher frequencies to Needham. There would also be some improved access to LMA, so there's some consolation.

Interestingly, I'm not sure if that makes a difference. There are two parts in play: travel time on the vehicle, and waiting time.

Suppose Needham trains run every 7.5 minutes (8 tph, as each GL branch does today), with a 1:1 split between Kenmore and Huntington (surface). If a rider arrives at Needham Junction and sees the next train is via Kenmore, obviously, all good. But what if the next train is via Huntington? Their options are:

• Take this train: 18 min beyond Brookline Village
• Wait for the next train: 7.5 min wait, 14 min via Kenmore -- 21.5 min total

So most riders will probably still take whichever comes first, and "suck up" the additional time from street-running, mostly because the alternative is even worse. (This doesn't consider time from Brookline Village to Riverway, but the conclusion still holds if that segment takes up to 3.5 minutes.)

The main difference is for riders who (1) check the schedule/app for which trains go via Kenmore, and (2) are flexible in what time they arrive at the station, so that they can use the 7.5-min wait for something else. But that kind of defeats the purpose of turn-up-and-go service.

(This is not to say that we should be content with Needham-via-surface, as the travel time is indeed longer and not ideal for the riders.)

You can also probably mitigate this in part by adding full transit lanes on Huntington/Route 9 all the way to Brookline Village. Even with a future underground connection, transit lanes would remain useful (if not vital) for 39 service.

The T is already planning for accessible platforms for the outer E, with designs by this July. This makes me wonder if we'll see dedicated transit lanes at least to Back of the Hill, as otherwise it's pretty hard to make them accessible.


D-E surface connector design thoughts

Option 3 is a more expensive build and would depend in part on how an eventual D-E subway connector is built, but is definitely a reasonable idea. (If our northside Urban Ring service -- my Bronze Line on my map -- is terminating at Brookline Village, you could make an argument to just extend that to Heath and maybe Hyde Sq. That would actually follow the same general patten as the original proposal for the T39.)

If you're willing to settle for a flat junction (which I made a case for above), a complete wye might not be totally crazy:

Turning radius is 66 ft. While it's a bit less than the 82' in the design handbook you found, it seems sufficient for the Green Line: the existing system has many curves that are tighter, including Government Center's revenue tracks.

However, this is where I'm not sure if a flat junction is sufficient, as you have three different services in all three possible directions. So here's a flying junction design for just D and N service:

(The 16' clearance is based on discussions here, and my measurements of a few GL portals on Google Earth Pro. The actual clearance needed may be even lower.)

Obviously, this design largely precludes a wye. I'm not sure if such (rather complex) infrastructure will be worth it -- especially if it's deemed sufficient to run Needham trains by simply cutting some Riverside trains -- but at least the short duck-under tunnel for the eastbound D can be reused for a more permanent tunnel eventually.

(If you're willing to dig deeper under the above-ground parking garage, it buys you a lot more space, but that may be more challenging and may affect the ability to reuse that tunnel in the future.)

 

[TheRatmeister]

Wait, I though you were proposing a flat junction all along... To me, it didn't look like there would even be space for a flying junction at Strathmore.

This is more in regards to terminating C trains at Reservoir, for any continuing service to Needham a flat junction would be necessary. Ideally though since there are 4 tracks at Reservoir, the C branch just feeds directly into the two side tracks, so terminating trains don't need to disturb the D branch at all.

D-E surface connector design thoughts

In terms of non-revenue operational benefits, I would consider this way more useful than the C-D connector. As I'm sure we're all aware at this point any disruption to service between Hynes and Park means that E trains can no longer reach a yard, and so can't run.

 

[Riverside]

In terms of non-revenue operational benefits, I would consider [a D-E connector] way more useful than the C-D connector. As I'm sure we're all aware at this point any disruption to service between Hynes and Park means that E trains can no longer reach a yard, and so can't run.

Yes, 100%.

Interestingly, I'm not sure if that makes a difference. There are two parts in play: travel time on the vehicle, and waiting time.

Suppose Needham trains run every 7.5 minutes (8 tph, as each GL branch does today), with a 1:1 split between Kenmore and Huntington (surface). If a rider arrives at Needham Junction and sees the next train is via Kenmore, obviously, all good. But what if the next train is via Huntington? Their options are:

• Take this train: 18 min beyond Brookline Village
• Wait for the next train: 7.5 min wait, 14 min via Kenmore -- 21.5 min total

So most riders will probably still take whichever comes first, and "suck up" the additional time from street-running, mostly because the alternative is even worse. (This doesn't consider time from Brookline Village to Riverway, but the conclusion still holds if that segment takes up to 3.5 minutes.)

The main difference is for riders who (1) check the schedule/app for which trains go via Kenmore, and (2) are flexible in what time they arrive at the station, so that they can use the 7.5-min wait for something else. But that kind of defeats the purpose of turn-up-and-go service.

(This is not to say that we should be content with Needham-via-surface, as the travel time is indeed longer and not ideal for the riders.)

Yeah, this is a reasonable analysis. The bigger remaining analysis, in my opinion, is indeed the scenario where Needham only runs via Huntington surface. But yes, I think a 1:1 split between Kenmore and Huntington would have enough mitigating factors that it could probably be a reasonable temporary strategy for a few years.

The T is already planning for accessible platforms for the outer E, with designs by this July. This makes me wonder if we'll see dedicated transit lanes at least to Back of the Hill, as otherwise it's pretty hard to make them accessible.

Yeah, I've had the same thought (and hope).

Having said that, I do notice there's a spur to the north with shorter platforms that connect directly to Chestnut Hill Ave, and the platforms seem just long enough to be modified for 2-car Type 10s (228', see below). So in such a world, terminating C trains can use that; although it will still interline with the D and N, which may make it infeasible or at least undesirable anyway.

Oh sorry, I thought we were talking about using those platforms all along. I have no idea how we would connect the C to the actual D platforms at Reservoir, at least not without a lot of concrete and disruption.

This also got me wondering: If there's demand for a more convenient C-D transfer -- especially if/when the D and N are rerouted to Huntington, South Station and Seaport, opening up several transfer possibilities -- would it be feasible to extend the C from Cleveland Circle to Reservoir, coming in from the west? Like this:

Depending where you measure from, this is something like 500 or 600 feet -- that's pretty close. But even if it becomes necessary in the future, it seems like it would be pretty easy to institute relatively quickly.

Some thoughts on the D-E Connector designs later (hopefully...).

In 1974, the MBTA began rebuilding the line to accommodate the new Boeing LRVs. From June 8 to September 11, Highland branch cars ran on Beacon Street from Reservoir to Kenmore. A temporary inbound-to-outbound turning loop was built east of Reservoir for the diversion. Inbound cars stopped at Reservoir, ran around the temporary loop, and up the outbound side of the regular loop towards Cleveland Circle. Outbound cars via Beacon Street ran down the inbound side of the regular loop, around the same temporary loop track, and then continued outbound from the station.

That's really interesting!