MBTA Red Line / Blue Line Connector

jbray said:
A user on Reddit is claiming that the public meeting revealed that there will be no provision for future expansion of the blue line as part of the build. The claim is that the cut and cover tunnel is not able to be waterproofed to the necessity required for either expansion and a deep bore tunnel would be to cost prohibitive to complete.
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So, when the Riverbank Subway was officially proposed in the early 1900's, that proposal was not buildable? I think if they could do it in 1910, they could do it now.
 
Teban54 said:
This just shows the T and the state have zero interest in forward planning besides the one single project that they're working on, if we're lucky.

Not putting in provisions now will inevitably make things even harder and more costly to build in the future. One recent example is NYC's 7 extension and the 10th Ave station.

(Edit: At least I hope the current design won't completely preclude an extension. In the 2021 plan shown below, elevators and stairs in several alternatives are directly at the end of the tracks, potentially preventing any extension from being built.)
View attachment 43637
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To be fair to them, further expansion of the Blue Line really exists in two places: on aB, and in Ari Ofsevit's head (though they do have crayon lines in some planning studies). Also, I believe the discussion of extensions (based on the Reddit) revolved mostly around extension to Kendall - an extension on F-Line's Storrow replacement concept would not obviously need to be deeper. Discussion on this site has never considered anything but the Storrow replacement (which is technically at-grade and not even in a tunnel for most of its length) to be realistic, so I don't see this as disappointing at all really.

From the Reddit:

And because there aren't any projects in consideration for further extensions, they can't future-proof it, even if they wanted to.
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It wouldn't be responsible to spend hundreds of millions of dollars future-proofing for a fantasy. Union-Porter GLX isn't like that: the future extension has been acknowledged by the MBTA as a possibility.
 
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Equilibria said:
To be fair to them, further expansion of the Blue Line really exists in two places: on aB, and in Ari Ofsevit's head (though they do have crayon lines in some planning studies). Also, I believe the discussion of extensions (based on the Reddit) revolved mostly around extension to Kendall - an extension on F-Line's Storrow replacement concept would not obviously need to be deeper. Discussion on this site has never considered anything but the Storrow replacement (which is technically at-grade and not even in a tunnel for most of its length) to be realistic, so I don't see this as disappointing at all really.

From the Reddit:



It wouldn't be responsible to spend hundreds of millions of dollars future-proofing for a fantasy. Union-Porter GLX isn't like that: the future extension has been acknowledged by the MBTA as a possibility.
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To be fair, because Cambridge St runs up a relatively steep hill, it's possible that any tunnel that would continue into Cambridge would need to start further into downtown. There's a reason that the Red Line crosses in a bridge (besides cost).

I've always found extending the Blue Line through Cambridge a tunnel too far. Anything going out to Allson and Watertown will just overload the Red Line, as people are transferring to get to areas the Blue Line doesn't serve. Figure out something with a Green Line branch and call it a day.
 
vanshnookenraggen said:
To be fair, because Cambridge St runs up a relatively steep hill, it's possible that any tunnel that would continue into Cambridge would need to start further into downtown. There's a reason that the Red Line crosses in a bridge (besides cost).

I've always found extending the Blue Line through Cambridge a tunnel too far. Anything going out to Allson and Watertown will just overload the Red Line, as people are transferring to get to areas the Blue Line doesn't serve. Figure out something with a Green Line branch and call it a day.
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Running a long-distance street-running Green Line branch from Watertown that has to wind through Brighton, Allston and BU before hitting any grade-separated ROW doesn't seem like it would provide Watertown adequate levels of transit that it deserves. (Allston maybe, as it involves much less street running.)

And while I'm not advocating for Blue-to-Cambridge, I doubt it will overload the Red Line any more so than the present-day no-build alternative, where people are taking the 70 and 71 buses from Watertown to Red. Should a BLX to Kendall, Central and Watertown be built, anyone whose destinations are closer to Government Center, State and Aquarium will continue on BL, or even transfer from RL to BL into downtown. You'll also take off a huge chunk of Kendall workers from RL.

My own crayon proposal has always been Blue to Kenmore, BU, under the Fitchburg ROW to Newton Corner, then turn north to Watertown (or maybe further west). Going through the riverbank has challenges, but I doubt it's as doomed as people are saying on Reddit posts like this.
 
Equilibria said:
To be fair to them, further expansion of the Blue Line really exists in two places: on aB, and in Ari Ofsevit's head (though they do have crayon lines in some planning studies). Also, I believe the discussion of extensions (based on the Reddit) revolved mostly around extension to Kendall - an extension on F-Line's Storrow replacement concept would not obviously need to be deeper. Discussion on this site has never considered anything but the Storrow replacement (which is technically at-grade and not even in a tunnel for most of its length) to be realistic, so I don't see this as disappointing at all really.
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Teban54 said:
My own crayon proposal has always been Blue to Kenmore, BU, under the Fitchburg ROW to Newton Corner, then turn north to Watertown (or maybe further west). Going through the riverbank has challenges, but I doubt it's as doomed as people are saying on Reddit posts like this.
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This is correct. If you're doing a Storrow trade-in, the Riverbank Subway is basically nothing more than a capped cut, a minimum of 20 feet shallower than a cut-and-cover subway with few of the waterproofing concerns therein. So if anything the tunnel would be ascending up just a little bit after turning out of Charles Circle. The state's only assuming that Storrow is a forever feature blighting the landscape, as that's the only reason it would have to be cut-and-cover or deep-bore. We're not attempting Riverbank at all if Storrow stays; that's the bottom line. Its existence is contingent on the removal of the parkway's midsection (at minimum a deletion of the EB carriageway and conversion of the WB carriageway into slow 2-lane park access road), because the capped cut is the only thing making the build cost halfway palatable. It'll cost self-defeating billions as cut-and-cover with active flood mitigations.


BLX-Kendall has always struck me as an excuse to not engage brain on doing a proper rapid-transit rail Urban Ring, the #1 or (depending on how you scale NSRL) #2 highest-ridership studied transit build out there. Nobody has quantified what BLX does that the UR through Kendall doesn't do equally well, and Ari O. pretty much stopped talking about it altogether once he was firmly pressed in online comments on what the difference was.
 
F-Line to Dudley said:
This is correct. If you're doing a Storrow trade-in, the Riverbank Subway is basically nothing more than a capped cut, a minimum of 20 feet shallower than a cut-and-cover subway with few of the waterproofing concerns therein. So if anything the tunnel would be ascending up just a little bit after turning out of Charles Circle. The state's only assuming that Storrow is a forever feature blighting the landscape, as that's the only reason it would have to be cut-and-cover or deep-bore. We're not attempting Riverbank at all if Storrow stays; that's the bottom line. Its existence is contingent on the removal of the parkway's midsection (at minimum a deletion of the EB carriageway and conversion of the WB carriageway into slow 2-lane park access road), because the capped cut is the only thing making the build cost halfway palatable. It'll cost self-defeating billions as cut-and-cover with active flood mitigations.
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I love the idea of taking this one step further and having BLX emerge to the surface from a portal in the current Storrow ROW just a bit north of the band shell. It would run at-grade but in a reserved ROW along the current path of Storrow before dipping underground again just before Mass Ave for a brief tunnel under the now interchange-free Charlesgate Park. The Kenmore terminus woud be cut-and-cover platforms under Beacon Street that would connect to the Green line on the west end and have an east entrace on the Charlesgate itself for a relatively quick walking transfer to the #1 bus. With this approach, you could also get a cheap but useful intermediate station around Dartmouth Street. Plus it would just be great urban design - Imagine riding a train out of the portal on a summer afternoon and seeing the view across the Esplanade with sailboats and the Cambridge skyline beyond!
 
michaelw37 said:
Plus it would just be great urban design - Imagine riding a train out of the portal on a summer afternoon and seeing the view across the Esplanade with sailboats and the Cambridge skyline beyond!
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I'm not sure I agree. I'd envision this in a future of 'boulevardized' Storrow, and a surface rapid transit line would be just as much of a barrier, if not more, to connecting back bay neighborhoods to the Charles and esplanade as 4 lanes of highwayesque traffic.
 
michaelw37 said:
I love the idea of taking this one step further and having BLX emerge to the surface from a portal in the current Storrow ROW just a bit north of the band shell. It would run at-grade but in a reserved ROW along the current path of Storrow before dipping underground again just before Mass Ave for a brief tunnel under the now interchange-free Charlesgate Park. The Kenmore terminus woud be cut-and-cover platforms under Beacon Street that would connect to the Green line on the west end and have an east entrace on the Charlesgate itself for a relatively quick walking transfer to the #1 bus. With this approach, you could also get a cheap but useful intermediate station around Dartmouth Street. Plus it would just be great urban design - Imagine riding a train out of the portal on a summer afternoon and seeing the view across the Esplanade with sailboats and the Cambridge skyline beyond!
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I would think that if the park access proponents actually won out to get the parkway deleted, then there's no way they would do park access that's in any way interrupted by a surface ROW excepting that aforementioned 2-lane slow park access road with traffic-calmed crosswalks at every street on the grid. But a capped cut is not that much more cost, and we can assume that the parkway deletion would come with transit trade-in stipulations to move an equal number of people as the parkway in the same project area to ensure that enough funds are directed to BLX. You'd dig down on the Storrow EB roadpack, frame the walls and floor, then slap on a roof that runs anywhere from 2-6 feet above the current Storrow pavement. Then landscape dirt on top ending at a re-poured Back St. retaining wall. The Back St. retaining wall can be redesigned to jut higher to act as a passive flood barrier for the Back Bay, with the roof of the tunnel and the on-top landscaping directing water passively back into the Basin. All told, it's cosmically less costly than cut-and-cover, which provisions for that 20 ft. utility 'sandwich' layer and goes quite a bit below the pavement level deeper into the landfilled mush.

I would assume that there'd be stations at Mugar Way/Hatch Shell and Mass Ave., but Dartmouth is probably a marginal prospect as GL-Copley captures most of that walkshed just fine. At Kenmore you'd need to underpin a small slice of the Green Line station with tail tracks aligned with Brookline Ave. to have any hope of extending further (bang-a-right under the Pike/B&A tracks for Allston/Watertown, or straight ahead for something in the LMA). But the vast majority of it is an ultra-shallow capped cut that provides open access to all that parkland.
 
Not to distract from the BLX discussion, but is it realistic to request this station be built with platform screen doors? What signaling enhancements does the blue line need to make this happen? Can these enhancements be made on the new track before they are rolled out to the entire line?
 
Badusername said:
Not to distract from the BLX discussion, but is it realistic to request this station be built with platform screen doors? What signaling enhancements does the blue line need to make this happen? Can these enhancements be made on the new track before they are rolled out to the entire line?
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Good question (not that I think the T would bother).

The Blue Line's signals are barely more sophisticated than the Green Line's (Blue's can at least stop trains that pass red signals), and in my understanding quite similar to those on the New York subway.

I'm no expert, but I can't imagine it would be that hard to wire platform screen doors into the track circuit so the signals couldn't clear until the doors were closed. Problem is, that doesn't necessarily prevent the train from moving (which, uh, would be extra bad if someone was caught between a train and the platform doors), because the signals' trip arms can only mechanically stop trains that pass the signals, there's no way to use that system as an interlock to prevent the train moving at all. Something like Red/Orange's ATO system would be more amenable to that kind of safety, because you could set it up such that until the doors are confirmed closed, the speed code stays at zero, and the train can't start moving at all. (The actual system on those lines is pretty old and due for replacement, so might not necessarily be upgradeable for doors on those lines, but it's kinda moot since Blue doesn't even have that system.)

Unless the #5 cars have some provision for communicating with platform doors (and I have no idea why they would, unless it's native-built into some generic component Siemens stuffed in there) you'd probably need to modify the cars (to interlock reliably with the doors), replace the signal system, or both. Meaning in MBTA-land either they simply don't bother with doors (though ideally building the station such that they can be added later), or they don't bother with any fancy upgrades and just have a person there to operate and oversee the doors.

(Most likely outcome is they don't bother.)
 
On the topic of a lack of provision for future extension: meh.

Beyond Charles/MGH, a Blue Line Extension drops from the literal top of the priority list to what I would guess is the bottom quarter of the list. If it does ever happen, it’ll be part of a megaproject. The only world in which that happens is one where the public is also willing to entertain a rebuild of Charles/MGH Under. I’m not super concerned about that future-proofing being moved out of scope.

To me, the bigger news — and it’s good news at that — is the decision to move forward with full cut & cover, apparently with the confidence that 4 lanes on Cambridge St will stay open at all times. This is huge. For one, it shows that the administration is actually interested in getting this thing built, and isn’t going to hide behind the fig leaves that often are trotted out in favor of TBM.

But the biggest piece, IMO, is that a successful C&C Blue-Red project will set a precedent for other C&C projects — and that’s a game changer.

With the exception of the Piers Transitway, the Blue-Red Connector will be the first subway built in Boston since the South Cove tunnel was built in the ‘60s. Prior to that, IIRC, the last subway was the Huntington Subway in the ‘40s. EDIT: @Teban54 rightfully points out that the Red Line extension to Alewife was both in living memory and not a cut-and-cover. I think I overlooked it originally because I was literally thinking about construction within Boston city limits. That being said, I think my point below still stands.

More EDIT: also, as noted by @Roxxma and @bakgwailo, a number of smaller tunnels built to connect new extensions, including Maverick-Airport, North Station-Community College, North Station-Science Park, and the last little bit of connection to connect the South Cove Tunnel to the surface.

Meanwhile, in the last two generations, the public’s exposure to tunnel projects has been:
  • The Big Dig — huge huge cost overruns
  • The Piers Transitway — what might be called by some a shuttlebus tunnel
  • The proposed NSRL — massive TBM project
  • The proposed Silver Line Phase III — a shockingly contorted proposal no matter which way you look at it
A successful C&C project could be game-changing in terms of public support for other modest tunneling projects, including things like T-under-D, an extended Huntington Subway, a new connection to the Pleasant Street Portal, and possibly even the modest amounts of tunneling that could be game-changing for various pieces of the Urban Ring.

So, at the moment, I feel okay about all this.
 
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Riverside said:
On the topic of a lack of provision for future extension: meh.

Beyond Charles/MGH, a Blue Line Extension drops from the literal top of the priority list to what I would guess is the bottom quarter of the list. If it does ever happen, it’ll be part of a megaproject. The only world in which that happens is one where the public is also willing to entertain a rebuild of Charles/MGH Under. I’m not super concerned about that future-proofing being moved out of scope.

To me, the bigger news — and it’s good news at that — is the decision to move forward with full cut & cover, apparently with the confidence that 4 lanes on Cambridge St will stay open at all times. This is huge. For one, it shows that the administration is actually interested in getting this thing built, and isn’t going to hide behind the fig leaves that often are trotted out in favor of TBM.

But the biggest piece, IMO, is that a successful C&C Blue-Red project will set a precedent for other C&C projects — and that’s a game changer.

With the exception of the Piers Transitway, the Blue-Red Connector will be the first subway built in Boston since the South Cove tunnel was built in the ‘60s. Prior to that, IIRC, the last subway was the Huntington Subway in the ‘40s.

Meanwhile, in the last two generations, the public’s exposure to tunnel projects has been:
  • The Big Dig — huge huge cost overruns
  • The Piers Transitway — what might be called by some a shuttlebus tunnel
  • The proposed NSRL — massive TBM project
  • The proposed Silver Line Phase III — a shockingly contorted proposal no matter which way you look at it
A successful C&C project could be game-changing in terms of public support for other modest tunneling projects, including things like T-under-D, an extended Huntington Subway, a new connection to the Pleasant Street Portal, and possibly even the modest amounts of tunneling that could be game-changing for various pieces of the Urban Ring.

So, at the moment, I feel okay about all this.
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Though to be fair, the only reason this is doable on Cambridge Street is that urban renewal cleared everything under it and it's really, really wide. I'm not sure Huntington presents as easy a shot, and I'm sure roads like Longwood Avenue don't.
 
Equilibria said:
Though to be fair, the only reason this is doable on Cambridge Street is that urban renewal cleared everything under it and it's really, really wide. I'm not sure Huntington presents as easy a shot, and I'm sure roads like Longwood Avenue don't.
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I mean yeah, we can debate the merits of any individual tunnel (and yeah, I wasn’t thinking of Longwood Ave, but more like, eg. Melnea Cass). But for the public overall, this will (hopefully) come down to “Oh, huh, not every tunnel has to be like the Big Dig”, which I think right now forms a base level of opposition to any tunneling whatsoever.

Everything will still be up for debate, but a successful C&C project would mean that, for example, a “Bury the B” subway under Commonwealth would at least get an honest airing in the public fora based on its particular merits, rather than on a knee-jerk skepticism of tunneling in general.
 
Riverside said:
On the topic of a lack of provision for future extension: meh.

Beyond Charles/MGH, a Blue Line Extension drops from the literal top of the priority list to what I would guess is the bottom quarter of the list. If it does ever happen, it’ll be part of a megaproject. The only world in which that happens is one where the public is also willing to entertain a rebuild of Charles/MGH Under. I’m not super concerned about that future-proofing being moved out of scope.

To me, the bigger news — and it’s good news at that — is the decision to move forward with full cut & cover, apparently with the confidence that 4 lanes on Cambridge St will stay open at all times. This is huge. For one, it shows that the administration is actually interested in getting this thing built, and isn’t going to hide behind the fig leaves that often are trotted out in favor of TBM.

But the biggest piece, IMO, is that a successful C&C Blue-Red project will set a precedent for other C&C projects — and that’s a game changer.

With the exception of the Piers Transitway, the Blue-Red Connector will be the first subway built in Boston since the South Cove tunnel was built in the ‘60s. Prior to that, IIRC, the last subway was the Huntington Subway in the ‘40s.

Meanwhile, in the last two generations, the public’s exposure to tunnel projects has been:
  • The Big Dig — huge huge cost overruns
  • The Piers Transitway — what might be called by some a shuttlebus tunnel
  • The proposed NSRL — massive TBM project
  • The proposed Silver Line Phase III — a shockingly contorted proposal no matter which way you look at it
A successful C&C project could be game-changing in terms of public support for other modest tunneling projects, including things like T-under-D, an extended Huntington Subway, a new connection to the Pleasant Street Portal, and possibly even the modest amounts of tunneling that could be game-changing for various pieces of the Urban Ring.

So, at the moment, I feel okay about all this.
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Red to Alewife is a subway, even though not a C&C.

My biggest concerns about the lack of provision for BLX beyond Charles isn't its lack of priority, but the fact that the design may preclude any such extension from ever being built (due to the blocking elevators and stairs). It's one thing to not expect it to be considered in the next 50 years; it's another to completely shut the door when we do want to build it in 50 years, 100 years, however long it might take.
 
Teban54 said:
Red to Alewife is a subway, even though not a C&C.
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D'oh. This is what I get for posting without coffee.

[Actually, I think I did think about this one, but I really was literally making a point about construction in Boston proper. Either way, will edit to acknowledge.]
 
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