Crazy Transit Pitches

[Riverside]

I’m still confused by why it would need to go somewhere else rather than just turn around at Central or Harvard? Also, why would it need to be HRT vs buried LRT?

Yeah, I agree -- it either works or doesn't work regardless of HRT or LRT, as long as we're talking about tunneling. I think turning around at Central doesn't work because you lose out on the Harvard transfers, and I think double-tunneling to Harvard ends up being hard to justify.

 

[stefal]

We're at this level anyways - any routing over to Union or even Sullivan for the eventual superstation?

 

[Charlie_mta]

Pre-1905 the Back Bay shoreline on the Cambridge side was Main & Sidney Streets, so the Red Line already traced out the limits of the ancestral shoreline bedrock on its route to the Longfellow. Every single block of MIT to the south of there has only existed for 115 years as very soft fill, with the Grand Junction RR being the only older extant structure as it was originally laid out in the middle of the Bay on an earthen causeway with multiple bridges crossing over marshy spits. The subsurface fill out there is very low-density, so for 2/3 mile underneath Mass Ave. to Memorial Drive you're not only going to have manifold difficulties waterproofing a subway tunnel...but also will have problems anchoring it from slight lateral movement.

Not disputing what you're saying, but the Green Line through the Back Bay (from Charles St. to Kenmore, except for around Mass. Ave.) was built cut-and-cover outside the original shoreline in a filled-in area, and goes even deeper to tunnel under the Muddy River. If it works in the Back Bay, why wouldn't a cut-and-cover under Mass Ave from Cambridge to South Bay work? Is the Back Bay a denser fill material? Of course a tunnel under the Charles River is a whole other matter, but I'm only addressing here a cut-and cover tunnel along Mass Ave.

 

[F-Line to Dudley]

Not disputing what you're saying, but the Green Line through the Back Bay (from Charles St. to Kenmore, except for around Mass. Ave.) was built cut-and-cover outside the original shoreline in a filled-in area, and goes even deeper to tunnel under the Muddy River. If it works in the Back Bay, why wouldn't a cut-and-cover under Mass Ave from Cambridge to South Bay work? Is the Back Bay a denser fill material? Of course a tunnel under the Charles River is a whole other matter, but I'm only addressing here a cut-and cover tunnel along Mass Ave.

Well...you kind of bury the whole of the lede right then and there. A new Mass Ave. subway doesn't have any real usefulness unless it crosses the river...so it doesn't matter if 4 blocks from Main to Vassar is conventional cut-and-cover, you're going deep under the river and needing to waterproof for the inclines + anchor that sucker from small movement under tidal influence some distance back to your would-be MIT Campus Station before the river. And that's a mighty budget blowout.

The Green Line is a beyond-useless comparison. It doesn't cross Charles Basin. It doesn't cut across the ancestral tidal influence while it's not crossing Charles Basin. It doesn't go deep (the Muddy River undercut is not deep). It doesn't matter if the Back Bay fill is the same or different as it is in Cambridge; YOU AREN'T ATTEMPTING REMOTELY THE SAME THING.


Why do those extremely fundamental differences strike anyone as gerrymanderable out of a direct comparison? That makes no bloody sense.

 

[Riverside]

Returning momentarily to Blue-Beyond-Kenmore. One thing that's interesting structurally about the Blue and Green Lines and how they fit into the overall network is that they are two half-lines that sorta form one disconnected whole. The spur to Lechmere notwithstanding, both lines basically just connect one series of suburbs each with downtown, as opposed to the Red and Orange Line, which have fully developed "legs" each on opposite sides of downtown.

Obviously GLX will put an end to all that, but for 100 years that's been the relationship, a reflection of their common heritage as streetcar tunnels.

Of course, early 20th century planners toyed with the idea of hooking the East Boston Tunnel into the Tremont Street Subway, which likely would have eventually resulted in the creation of a Kenmore-to-Maverick subway, likely with the current Green Line branches at one end, and probably an LRT-conversion of the Boston, Revere Beach & Lynn Railroad on the other.

But I think this is part of why a Blue-Beyond-Kenmore conversation is inherently a bit more "mysterious" or "confounding" than other stuff we talk about. Most of the other extensions we discuss are along well-established corridors that were outlined as long ago as 1945 -- Orange to Reading, Blue to Lynn, Orange to W Roxbury, Green to Needham, "something" to Arlington, and "something" along the Mass Pike, etc. Of those 1945 corridors, the obvious remaining gap which Blue could slot into is along the Mass Pike, but... we've kinda already figured out a good way to serve that corridor -- Indigo Line EMUs comingled with regional rail. No tunneling required (and worth noting that the 1945 proposal would not have entailed tunneling either, but rather partial ROW conversion). And the 1945 vision of through-run rapid transit in a loop out the B&A and back the Highland Branch obviously is never going to happen.

But with that "obvious" candidate suddenly looking like much less of a surefire thing... then suddenly we have the whole universe open to us again. You have everything from "Kenmore-Riverway-Forest Hills" to "Kenmore-Brighton-Riverside" to "Kenmore-Watertown-Waltham" to "Kenmore-Harvard" to "Waltham or Riverside, but via MIT instead of Kenmore" to "alt route to Harvard via Cambridge and then Watertown", even to crazier stuff like "Blue eats GLX" or even the occasional "Blue bends back to hit Charlestown and Chelsea".

Obviously some of these are more buildable than others -- for example, I don't think Watertown or Waltham are ever gonna be reached by rail via Kenmore -- but I don't think any one corridor is that much more obvious than any of the others. And I think that's why a consensus for Blue-Beyond-Kenmore -- hell, even Blue-Beyond-Charles -- is very hard to reach. The "natural" layout of the T would call for a Revere-Highland Branch line paired with a Woburn-B&A line. But since the B&A is unavailable now, it'll be much more "situationally dependent" as to where the Blue should go after Kenmore -- assuming it ever makes it that far, and whether it should even go further than that.

(Parenthetically -- I dislike the idea of sending the Blue Line down toward Riverway. That points it to eventually getting extended all the way down Forest Hills, and I see very little use for that. I'd rather see an extension out toward Allston, under the theory that you could eventually extend it out further from there, if you chose.)

 

[Blackbird]

Well...you kind of bury the whole of the lede right then and there. A new Mass Ave. subway doesn't have any real usefulness unless it crosses the river...so it doesn't matter if 4 blocks from Main to Vassar is conventional cut-and-cover, you're going deep under the river and needing to waterproof for the inclines + anchor that sucker from small movement under tidal influence some distance back to your would-be MIT Campus Station before the river. And that's a mighty budget blowout.

What about expanding the Mass Ave bridge so a subway line could cross à la the Longfellow?

 

[JeffDowntown]

What about expanding the Mass Ave bridge so a subway line could cross à la the Longfellow?

For that to help, you would need to use a stretch of elevated rail on both sides of the bridge to get the eventual inclines and portals back into solider fill or actual land. Likely your first stations either side would need to be in the EL sections (like Charles/MGH).

I don't see either MIT or Back Bay tolerating ELs!

 

[F-Line to Dudley]

For that to help, you would need to use a stretch of elevated rail on both sides of the bridge to get the eventual inclines and portals back into solider fill or actual land. Likely your first stations either side would need to be in the EL sections (like Charles/MGH).

I don't see either MIT or Back Bay tolerating ELs!

Yeah, hell no. Or Cambridge, which killed the one planned up Main St./Mass Ave. to Harvard Sq. 110 years ago forcing it to be subway-dug.

 

[Blackbird]

For that to help, you would need to use a stretch of elevated rail on both sides of the bridge to get the eventual inclines and portals back into solider fill or actual land. Likely your first stations either side would need to be in the EL sections (like Charles/MGH).

I don't see either MIT or Back Bay tolerating ELs!

Isn’t the reason for Charles/MGH being elevated the topography of Beacon Hill? Going from underground at Hynes to the Mass Bridge doesn’t seem like it’d be as tricky as going from underground at Park St to the Longfellow?

 

[George_Apley]

Isn’t the reason for Charles/MGH being elevated the topography of Beacon Hill? Going from underground at Hynes to the Mass Bridge doesn’t seem like it’d be as tricky as going from underground at Park St to the Longfellow?

Elevation might have something to do with it... I don't know. But I assume it's mostly because it's basically still on the bridge at that point. There's no way to do a subway station at Charles Circle if the train is also crossing the river on the Longfellow Bridge.

 

[Charlie_mta]

What about expanding the Mass Ave bridge so a subway line could cross à la the Longfellow?

Physically it looks possible on the Cambridge side to have an at-grade portal ramp similar to the one approaching the Longfellow Bridge. It would require widening Mass Ave and cutting down trees on either side next to MIT, for which there is room, and eliminating cross-street access along that stretch. I was going to draw a map showing that layout, which wouldn't be all that bad, although I doubt MIT would ever approve it. What stopped me from pursuing this idea is the Back Bay approach, which would be impossible due to the lack of space to widen Mass Ave and also Beacon St crossing Mass Ave fairly close to the river, providing inadequate runout distance for the portal ramp.

I think a better overall solution is a Green Line Urban Ring using the Grand Junction route plus a GL branch to Harvard Square via West Station and Allston. It wouldn't provide the direct service that an HRT along the #1 Bus route would, but it would be a close second.

 

[Blackbird]

What stopped me from pursuing this idea is the Back Bay approach, which would be impossible due to the lack of space to widen Mass Ave and also Beacon St crossing Mass Ave fairly close to the river, providing inadequate runout distance for the portal ramp.

Crazy idea, but this is the place for it: could the subway line start the descent earlier on the Back Bay side? Like, start ducking down when it gets 50-75% across the bridge from Cambridge? Kind of a compromise between tunneling under the river and going over?

Granted it might mess with the pedestrian walkway under the bridge and Storrow might be a complication (unless Storrow too was changing with this redesign), but I already don’t know if the base concept is sound.

 

[F-Line to Dudley]

I think a better overall solution is a Green Line Urban Ring using the Grand Junction route plus a GL branch to Harvard Square via West Station and Allston. It wouldn't provide the direct service that an HRT along the #1 Bus route would, but it would be a close second.

This is the correct answer. CT2 has higher ridership than CT1, and for the 1 + campus shuttle patrons who are just crossing the river and not going as deep as South End the UR will pry significant ridership away. After that gap is filled I can't see how at minimum the ensuing 2-3 generations won't be all-set by the rapid transit connectivity crossing Mass Ave. every mile or less the whole way down the corridor.

 

[Max Power]

General question - but how hard would it be to future-proof the corridor and cut-cover a subway tunnel the length of Melnea Cass from Tremont to Mass Ave?

It could serve as a critical link in the urban ring, and future construction could go further in either direction.

This area was cleared out with urban renewal, right? With a pretty wide ROW, I think this could be a feasible project and if they're going to rip up trees... might as well do it now -

 

[F-Line to Dudley]

General question - but how hard would it be to future-proof the corridor and cut-cover a subway tunnel the length of Melnea Cass from Tremont to Mass Ave?

It could serve as a critical link in the urban ring, and future construction could go further in either direction.

This area was cleared out with urban renewal, right? With a pretty wide ROW, I think this could be a feasible project and if they're going to rip up trees... might as well do it now -

It's urban renewal nuke zone, yes...but Melnea Cass is the only isolated stretch of it all around. Getting up Washington in a dig is a blowout-and-a-half in utility relocation under a much older street, and trying to string together the Urban Ring has the killer issue of there being fuckall suitable streets spanning Kenmore to Ruggles.

Where you could, however, see future action is at the Mass Ave. intersection where trenching under from approaches on the Melnea Cass median + Mass Ave. Extension median can link together the Nubian-Southie SE quadrant Urban Ring as BRT (or, less likely, LRT). If Southie Bypass Rd. were realigned over a pre-demolished Widett Circle to square up with Mass Ave. Ext. you would basically have the most traffic-managed humanly imaginable setup for flinging between Nubian and the Transitway-via-Haul Rd. on one fork, Nubian to JFK on the other...each with the fewest traffic lights possible. And it would also be possible to do platforms down in the pit under Mass Ave. for that route if egresses fanned out to the 4 corners of that sprawling intersection.


^This^ practical consideration was for-real entertained by the Urban Ring scoping plan, which would make it a definite first move to take advantage of. While the under-street environs are clean for future subwaying, you still have too many "can't get there from here" blockers n' blowouts rung up just on the streets that connect at one end or the other to Melnea Cass, so that's not going to be Crazy Pitching anyone makes serious attempt at for multiple generations. Running a reservation line on Melnea Cass-proper with the Mass Ave. duck-under and thru-routing to the restricted Haul Road does a generational solid unto itself as the UR SE quadrant's likeliest build configuration.

 

[DominusNovus]

Just as a general thought experiment, if the NSRL were under way, and somebody decided that they wanted to push the tunnel portals as far out of Boston as possible, at what point would you cross the line between “crazy” and “F-line hates us just for asking?”

 

[JeffDowntown]

Just as a general thought experiment, if the NSRL were under way, and somebody decided that they wanted to push the tunnel portals as far out of Boston as possible, at what point would you cross the line between “crazy” and “F-line hates us just for asking?”

The point where you miss a key branch point or the first commuter rail stop you need to hit (think approach to Back Bay Station, or Southhampton Yard, Innerbelt facility in Somerville). Probably why the portals are planned pretty close in.

 

[DominusNovus]

The point where you miss a key branch point or the first commuter rail stop you need to hit (think approach to Back Bay Station, or Southhampton Yard, Innerbelt facility in Somerville). Probably why the portals are planned pretty close in.

Though it may not have been clear, my question was asked in the spirit of burying the stations, as well. So nothing would be skipped, just more would be underground.

 

[JeffDowntown]

Though it may not have been clear, my question was asked in the spirit of burying the stations, as well. So nothing would be skipped, just more would be underground.

I think the branch points are larger deal breakers. Yard access and multi-branch lines.

 

[George_Apley]

Though it may not have been clear, my question was asked in the spirit of burying the stations, as well. So nothing would be skipped, just more would be underground.

That would preclude surface terminals for those stations at North and South. What's the benefit of having portals farther away?