Green Line Reconfiguration

[F-Line to Dudley]

Blue Line cars fit Green Line dimensions everywhere except possibly Boylston curve proper. And only possibly, because Bowdoin curve is just about the tightest HRT curve in the world. Widening out the curve would be more a necessity because of the excruciating speed restriction it would induce rather than the cars either not physically making it or needing more than a negligible smidge of extra breathing room to make it. Old Orange Line cars (slightly smaller than today's OL cars, but bigger than Blue) did go Haymarket portal to Pleasant St. portal from 1901-1909, and all subsequent tunneling (Kenmore 1919, B/C branch portals 1932, Huntington subway 1940, D portal 1959, GC-Haymarket 1963, North Station 2004) were each built with future-proofing.


The problem is simply what you'd do with all the branches you wouldn't be able to run that way. When BERy first toyed with the idea there was still a dense enough streetcar network where the C and E looping at transfer stations provided adequate scale connected to the rest of the network, and losing the B from Packards Corner to Chestnut Hill Ave. in lieu of a single HRT subway through Brighton Center wouldn't have been a crippling loss because the 66 trolley on Harvard Ave. would've taken up as cross-Allston load-bearing route from an easy HRT transfer on Harvard @ Brighton Ave.

That scale is lost and really can't be built back, so you lose too much in a conversion to be able to stitch the orphaned branch parts back together. You also lose the ability to run all that many branches period by trading wider train spacing for longer trains with HRT conversion, and can't negotiate grade crossings which are probably going to exist in some hard-to-eliminate residual spots on the Urban Ring (Main St. + Broadway, Cambridge; 6th St./Arlington St., Chelsea; the Upper Falls-Needham Center section of the Needham Branch if external forces with Orange and commuter rail force Town of Needham's service to get traded between modes; etc., etc. You also have some major issues lengthening the subway stations to 6 cars if you want to take advantage of the full capacity of HRT.

In short, there's just too many compromises in an outright 100% conversion that take a half-dozen extra improbable-difficulty megaprojects to compensate for all the potential transit loss on the branches. If you read back in this thread the evidence is pretty conclusive that with full state-of-repair and load-spreading trunks that light rail not only can perform hugely better than the sickly Green Line does today...but that it's massively scalable in ways that HRT isn't. HRT works best as linear extensions out to Route 128 in each direction, preferably with minimal branching since the 3 lines aren't interoperable, can't easily be wrapped around each other in trajectories logical enough to demand patterns to force-fit them as interoperable, and don't have the huge track miles of express tracks that NYC Subway has enabling a lot of run-thru interoperability. So we have to pick our modes by role. Having a robust LRT network to scale off of lets Boston develop more crisscrossing transit density so the capacity of the HRT lines doesn't have to be warped into an ill-suited role of branching here, branching there, branching everywhere.


Now, as a load-bearing companion to the Central Subway you can absolutely leverage a future teardown of Storrow Drive--or at least the eastbound carriageway while westbound is left as a two-lane low-capacity park road--with a mandatory transit trade-in requirement, extend the Blue Line from Charles MGH to Kenmore, and have a full-on second trunk freeing up the heaviest-ridership part of the Central Subway for demand originating elsewhere. That was a real and almost-enacted proposal a century ago, and the Storrow-for-transit trade-in is the one avenue that could realistically revive the proposal (graduating to build...another matter; serious debate...yes, potentially). You would then have options for extending Blue past Kenmore. The D seems obvious, although--caveat--the branching AND grade crossing situations are likely to rear their head with the Needham Branch when NEC congestion and the need for eventual Orange extension to the neighborhoods past Forest Hills tag-team to squeeze Needham off of the commuter rail mode. You'll never totally be free and clear of those HRT vs. LRT compromises, so pick your battles judiciously. There's plenty of linear expansion potential on all 3 HRT lines to whet one's appetite, and plenty of ways to reimagine the LRT network keeping it--and maximizing it--as LRT. There'll never be a loss of choices for using every mode to its natural advantages. They're all tools in the transit toolbox.

 

[bigeman312]

Now, as a load-bearing companion to the Central Subway you can absolutely leverage a future teardown of Storrow Drive--or at least the eastbound carriageway while westbound is left as a two-lane low-capacity park road--with a mandatory transit trade-in requirement, extend the Blue Line from Charles MGH to Kenmore, and have a full-on second trunk freeing up the heaviest-ridership part of the Central Subway for demand originating elsewhere. That was a real and almost-enacted proposal a century ago, and the Storrow-for-transit trade-in is the one avenue that could realistically revive the proposal (graduating to build...another matter; serious debate...yes, potentially). You would then have options for extending Blue past Kenmore. The D seems obvious, although--caveat--the branching AND grade crossing situations are likely to rear their head with the Needham Branch when NEC congestion and the need for eventual Orange extension to the neighborhoods past Forest Hills tag-team to squeeze Needham off of the commuter rail mode. You'll never totally be free and clear of those HRT vs. LRT compromises, so pick your battles judiciously. There's plenty of linear expansion potential on all 3 HRT lines to whet one's appetite, and plenty of ways to reimagine the LRT network keeping it--and maximizing it--as LRT. There'll never be a loss of choices for using every mode to its natural advantages. They're all tools in the transit toolbox.

Agreed. Although, I'm convinced that LRT is currently best for the Highland Branch (current "D" Branch of the Green Line). Send the Blue Line to Charles/MGH. Then, send the Blue Line to Kenmore. Then, stop there. The Blue Line needs to go to Charles/MGH now, though. That is obvious. Once that is built, there will be a much easier argument for Blue to Kenmore.

 

[nick]

Agreed. Although, I'm convinced that LRT is currently best for the Highland Branch (current "D" Branch of the Green Line). Send the Blue Line to Charles/MGH. Then, send the Blue Line to Kenmore. Then, stop there. The Blue Line needs to go to Charles/MGH now, though. That is obvious. Once that is built, there will be a much easier argument for Blue to Kenmore.

Thanks for the great response, F-Line.

I agree that the Blue Line at least needs to go to Kenmore, if anything to provide another outlet for crush loads during Sox games. The Green Line is a nightmare for day-to-day commuters during games. Personally I'd like a branch of the Blue Line to extend down Brookline Ave and terminate at Brookline Village, and another branch to extend to Watertown or Harvard as discussed elsewhere on this board.

 

[bigeman312]

Thanks for the great response, F-Line.

I agree that the Blue Line at least needs to go to Kenmore, if anything to provide another outlet for crush loads during Sox games. The Green Line is a nightmare for day-to-day commuters during games. Personally I'd like a branch of the Blue Line to extend down Brookline Ave and terminate at Brookline Village, and another branch to extend to Watertown or Harvard as discussed elsewhere on this board.

Now you are talking about tunneling HRT through less-dense areas with lower ridership and lower frequency. That will skew the cost benefit further into the "no-go" zone. Brookline/Longwood <->Fenway/Back Bay transit upgrades would be better handled by upgrading the "E" Branch (by continuing the subway to Brigham Circle and possibly connecting the Huntington Ave Subway to the "D" Branch).

Watertown or Harvard are probably best handled by a branch of the Green Line. The density and desired stop-spacing out there calls for LRT more than HRT. The option for more surface routing of LRT is another added bonus. First, some BRT would go a long way around those areas.

 

[davem]

Send HRT where it works: dense areas with long distances between stations and a dedicated row.

Send LRT where it works: dense areas with short distances between stations, a dedicated row, and multiple branches with crisscrossing trunk lines.

The green line with a few new connections, extensions, and DO IT NOW upgrades like signal priority has massive potential to be far better than it is, and better then it could be converted to heavy rail.

Something like this

Cleveland Circle - Airport via Boylston
Riverside - West Medford via Boylston
Needham - Seaport via Huntington
Hyde Square - Watertown via Huntington
Dudley to Boston College via Grand Junction

 

[Riverside]

Dudley to Boston College via Grand Junction

Can I just say that I am irrationally attached to this idea? (Kicking the Boston College line across to the Grand Junction.) It was discussed a long ways back in the Crazy Transit Pitch thread, and it has a number of downsides, but I still get a nice kick out of it.

 

[cbrett]

In a post NSRL world how important is load spreading Green through things like Blue to Kenmore? Let's pretend that we get current GLX plans, then Blue-Red @ MGH, and finally the NSRL, then what's the T's next move?

I'm thinking that signal priority, burying the B, and a Huntington Subway become the next moves. If the Green branches become more predictable to dispatch and downtown loads are lessened by NSRL, then would we still need more Central Subway capacity? With the core loads taken care of by the new Blue-Red and North-South Station transfers, then would the Green Line's future reside in more branches feeding the Central Subway (F-Line to Dudley, Needham,etc)? Or would the Green Line focus more in an Urban Ring increasing connectivity? (Grand Junction, converting silver line)

Considering the lack of connectivity between the CR and Green Line, I'm not sure that NSRL seriously changes the T's plans for Green Line expansion, but it's interesting to consider at least. Thoughts?

 

[George_Apley]

In a post NSRL world how important is load spreading Green through things like Blue to Kenmore? Let's pretend that we get current GLX plans, then Blue-Red @ MGH, and finally the NSRL, then what's the T's next move?

I'm thinking that signal priority, burying the B, and a Huntington Subway become the next moves. If the Green branches become more predictable to dispatch and downtown loads are lessened by NSRL, then would we still need more Central Subway capacity? With the core loads taken care of by the new Blue-Red and North-South Station transfers, then would the Green Line's future reside in more branches feeding the Central Subway (F-Line to Dudley, Needham,etc)? Or would the Green Line focus more in an Urban Ring increasing connectivity? (Grand Junction, converting silver line)

Considering the lack of connectivity between the CR and Green Line, I'm not sure that NSRL seriously changes the T's plans for Green Line expansion, but it's interesting to consider at least. Thoughts?

I think Riverbank Subway bringing Blue to Kenmore is way way DOWN the priority list. Buried B to BU Bridge, Green to Harvard, Buried E-Line to Brigham, the D to E connector and the "choose your own adventure" Tremont Tunnel project are all ahead of a parallel Back Bay line that loses a lot of its catchment to the River. I think Red to Arlington is ahead of Riverbank. I think Red under Red in Dorchester is ahead of Riverbank.

There are not many things that I would boot down the road to after Blue to Kenmore via Riverbank. It's just not a high priority at all.

 

[F-Line to Dudley]

Agree. It's pretty much a non-entity if you're strictly going by priority list.

The one and only one scenario where it comes into play is if. . .

1) public demand tilts overwhelmingly in favor of a Storrow Drive teardown west of Charles Circle
2) teardown of the parkway comes with a mandatory transit trade-in requirement
3) the transit trade-in requirement comes with a stipulation of serving the same end of Back Bay most affected by Storrow


In that case and that case only you have a binding transit commitment, an acute need for the replacement project to take the extra loads off the Central Subway, and a location-specific area that has to be addressed by the binding commitment.

Now, theoretically that could put the Huntington spine on the board. And in a nice-and-clean decision making universe you'd frame that as the Central Subway load reliever by virtue of giving lower Beacon St./Comm Ave. a less crowded Central Subway. But nothing's ever nice and clean.

The Huntington spine is incredibly expensive and has many surrounding impacts, moreso than decommissioning a parkway and building something different on the same exact footprint. To do it with Green you have to incorporate a lot more of the ops-side 'reimagining' and mix-and-match destination pairs discussed here, and have your ideal state-of-repair ready to go beforehand. So while you may be able to place a higher overall value judgment on the Pike-side Green spine vs. the river-side Blue spine, the Green spine is one that is a Really Big Thing™ requiring a really big city-wide commitment from many institutions (state, city, citizen, and private) to get behind the whole pan-corridor thing and its moving parts. There's understandable doubts whether all our institutions are up for that challenge now entering the second decade of post-Big Dig hangover with a reinforcing shot of post-B24 hangover.


Riverbank has these expediency advantages going for it that accomplish a whole lot of load relief without needing to put together another coalition-to-end-all-coalitions for a Really Big Thing™. The construction impacts are obviously bare minimal with a recycle of the Storrow EB carriageway, auto tunnel, and deep road cut under Mass Ave. shaving some parts off the cost. And operating Blue--the most over-capacity line on the system by far--on a 1.7 mile straight-line extension from Red-Blue @ Charles to Kenmore Under @ roughly BU Myles Standish Hall requires no ops practice changes like the Green trunk would require 'reimagination' of destination pairs and the involved ops practices.


So, say we successfully reach binding decision to tear down the Bowker Overpass in 5 years, the new Pike WB ramps downtown get built in short order after the Pike realignment, and MassDOT comes to its senses and waives the tolls completely for everyone traveling just between Allston and 93 to quash all that Storrow induced demand from the toll evaders. And it's as much a success that we expect it will be. I think in most of these AB threads re: Storrow we're all pretty much sticking with a conservative 2035-40 timeframe as the realistic measuring stick for attitudes changing enough for people and institutions to get over their fear about whacking Storrow totally west of Charles. But let's say for argument's sake we get surprised by how quickly those attitudes overturn and the "Tear the fucker out!" drumbeat starts going from loud to emerging consensus in the 2025-30 range instead.

You need the transit trade-in to proceed and need it now for taking any shovel-in-ground action on Storrow, but in 2030 Green's still swallowing closeout costs on the backside of its (hopefully completed) state-of-repair construction and new state-of-art signal system. Maybe we've even picked back up the Seaport LRT connector and resumed design, but because of the dozen-year mothballing it can't realistically see first shovel in ground until 2030. And you need to be on the backside of digesting that megaproject because it's one of the moving parts the Huntington spine hangs its hat on.

Well...what's the most expedient way to proceed quickly/cleanly with Storrow trade-in and achieve the lion's share of the trade-in's goals? Riverbank now looks like a lot more straightforward an option vs. waiting turn on the LRT project queue. It's an era-specific straightforwardness, but let's face it...you're not sacrificing one project over the other, just reshuffling the deck. The Huntington spine has MANY other stakeholders driving the demand to eventually get it done, and at 50-year projections when 'reimagined' Green + UR is substantially complete it's well possible that Kenmore may need to be flanked on the river's side all the same. Expediency forces a bang-bang decision on reshuffling the deck, but it's all good nonetheless. Kenmore ends up getting its load reliever sooner, and the H spine gets a little more time to sort out its enormous complexity and incremental-build phases without decades of Kenmore suffocating in overload during that wait.

Riverbank no doubt has a narrow path of converging circumstances that get it built at all...and it's all predicated on how fast the city hits consensus on making Storrow gone. Us amateur planners may want a more perfect sequence following more perfect transit project priority, but is this a reshuffle you'd be willing to make if it means we can rectify the Storrow mistake 10 years sooner and get Kenmore transit relief 10-15 years sooner than the H spine WITHOUT precluding or necessarily harming the independent viability of other options?

Yeah, I think take yourself out of a perfect world and put yourself in a real world where immediate decisions need rationalization and that's a short-term bargain you very seriously consider making.

 

[tangent]

It's a crazy transit-pitch, given it involves widening tunnels under the undocumented Back Bay fill with unknown water-table and unmapped utilities, yadda, yadda, yadda.

If the crazy pitch happened it would probably look like the Blue Line part of the BussesAin'tTrains proposal below. It's probably just as cheap (as in not cheap at all), and more beneficial to keep the Green Line as light rail and add a Riverbank Blue Line:

Crazy Transit Pitch

EDIT: TANGENT: bring something new to the conversation and stop with your worn-out anti-transit schtick. You lost all credibility the second you proposed getting rid of all other kinds of transportation and paving over everything for automobiles. 1970 called, and they said: "1955 called."

EDITX2: Welcome to the forum, Nick!

Trains are so cool and everyone should have one... Is that better?

 

[F-Line to Dudley]

Trains are so cool and everyone should have one... Is that better?

If by "better" you mean painting a big target on your back saying, "Please mock me; I'm volunteering for the arse-end of the AB maturity scale that's been vacant ever since that paste-eating Armpits kid relocated away to troll the Philly-area boards."

Unless that's what you actually want, then...knock yourself out.

 

[Shepard]

Agree. It's pretty much a non-entity if you're strictly going by priority list.

The one and only one scenario where it comes into play is if. . .

1) public demand tilts overwhelmingly in favor of a Storrow Drive teardown west of Charles Circle
2) teardown of the parkway comes with a mandatory transit trade-in requirement
3) the transit trade-in requirement comes with a stipulation of serving the same end of Back Bay most affected by Storrow


In that case and that case only you have a binding transit commitment, an acute need for the replacement project to take the extra loads off the Central Subway, and a location-specific area that has to be addressed by the binding commitment.

Now, theoretically that could put the Huntington spine on the board. And in a nice-and-clean decision making universe you'd frame that as the Central Subway load reliever by virtue of giving lower Beacon St./Comm Ave. a less crowded Central Subway. But nothing's ever nice and clean.

The Huntington spine is incredibly expensive and has many surrounding impacts, moreso than decommissioning a parkway and building something different on the same exact footprint. To do it with Green you have to incorporate a lot more of the ops-side 'reimagining' and mix-and-match destination pairs discussed here, and have your ideal state-of-repair ready to go beforehand. So while you may be able to place a higher overall value judgment on the Pike-side Green spine vs. the river-side Blue spine, the Green spine is one that is a Really Big Thing™ requiring a really big city-wide commitment from many institutions (state, city, citizen, and private) to get behind the whole pan-corridor thing and its moving parts. There's understandable doubts whether all our institutions are up for that challenge now entering the second decade of post-Big Dig hangover with a reinforcing shot of post-B24 hangover.


Riverbank has these expediency advantages going for it that accomplish a whole lot of load relief without needing to put together another coalition-to-end-all-coalitions for a Really Big Thing™. The construction impacts are obviously bare minimal with a recycle of the Storrow EB carriageway, auto tunnel, and deep road cut under Mass Ave. shaving some parts off the cost. And operating Blue--the most over-capacity line on the system by far--on a 1.7 mile straight-line extension from Red-Blue @ Charles to Kenmore Under @ roughly BU Myles Standish Hall requires no ops practice changes like the Green trunk would require 'reimagination' of destination pairs and the involved ops practices.


So, say we successfully reach binding decision to tear down the Bowker Overpass in 5 years, the new Pike WB ramps downtown get built in short order after the Pike realignment, and MassDOT comes to its senses and waives the tolls completely for everyone traveling just between Allston and 93 to quash all that Storrow induced demand from the toll evaders. And it's as much a success that we expect it will be. I think in most of these AB threads re: Storrow we're all pretty much sticking with a conservative 2035-40 timeframe as the realistic measuring stick for attitudes changing enough for people and institutions to get over their fear about whacking Storrow totally west of Charles. But let's say for argument's sake we get surprised by how quickly those attitudes overturn and the "Tear the fucker out!" drumbeat starts going from loud to emerging consensus in the 2025-30 range instead.

You need the transit trade-in to proceed and need it now for taking any shovel-in-ground action on Storrow, but in 2030 Green's still swallowing closeout costs on the backside of its (hopefully completed) state-of-repair construction and new state-of-art signal system. Maybe we've even picked back up the Seaport LRT connector and resumed design, but because of the dozen-year mothballing it can't realistically see first shovel in ground until 2030. And you need to be on the backside of digesting that megaproject because it's one of the moving parts the Huntington spine hangs its hat on.

Well...what's the most expedient way to proceed quickly/cleanly with Storrow trade-in and achieve the lion's share of the trade-in's goals? Riverbank now looks like a lot more straightforward an option vs. waiting turn on the LRT project queue. It's an era-specific straightforwardness, but let's face it...you're not sacrificing one project over the other, just reshuffling the deck. The Huntington spine has MANY other stakeholders driving the demand to eventually get it done, and at 50-year projections when 'reimagined' Green + UR is substantially complete it's well possible that Kenmore may need to be flanked on the river's side all the same. Expediency forces a bang-bang decision on reshuffling the deck, but it's all good nonetheless. Kenmore ends up getting its load reliever sooner, and the H spine gets a little more time to sort out its enormous complexity and incremental-build phases without decades of Kenmore suffocating in overload during that wait.

Riverbank no doubt has a narrow path of converging circumstances that get it built at all...and it's all predicated on how fast the city hits consensus on making Storrow gone. Us amateur planners may want a more perfect sequence following more perfect transit project priority, but is this a reshuffle you'd be willing to make if it means we can rectify the Storrow mistake 10 years sooner and get Kenmore transit relief 10-15 years sooner than the H spine WITHOUT precluding or necessarily harming the independent viability of other options?

Yeah, I think take yourself out of a perfect world and put yourself in a real world where immediate decisions need rationalization and that's a short-term bargain you very seriously consider making.

This is pretty convincing. And if accomplished, raises the question of whether the parallel Huntington subway needs to be done at all. After all, is it such a tremendous bug that riders from the west would need to switch trolleys at Boylston for either Dudley or Seaport via Pike (and vice versa)?

Overall, I feel Riverbank Blue is underrated. It's not just about relieving green but about better connectivity from Fenway and Back Bay and all points West to the airport, and Eastie/Revere/points northeast to major employment centers.

 

[tangent]

If by "better" you mean painting a big target on your back saying, "Please mock me; I'm volunteering for the arse-end of the AB maturity scale that's been vacant ever since that paste-eating Armpits kid relocated away to troll the Philly-area boards."

Unless that's what you actually want, then...knock yourself out.

I'd respond, but I don't want to interrupt the time you guys spend playing with trainsets in your parents basement

 

[F-Line to Dudley]

This is pretty convincing. And if accomplished, raises the question of whether the parallel Huntington subway needs to be done at all. After all, is it such a tremendous bug that riders from the west would need to switch trolleys at Boylston for either Dudley or Seaport via Pike (and vice versa)?

Overall, I feel Riverbank Blue is underrated. It's not just about relieving green but about better connectivity from Fenway and Back Bay and all points West to the airport, and Eastie/Revere/points northeast to major employment centers.

Oh, you still have to do it eventually. It may get reshuffled later, but since there are several phases spread over at least a likely 25-year span (if there's no let-ups) for actually stringing the whole trunk together from South End to Brookline Villiage at full capacity...the only functional difference means there's less pressure on the clock for finishing every single piece of it pedal-to-the-metal. Maybe a couple of the toughest chunks just lollygag around another decade or two under less pressure to hurry-up and finish. But this 'reimagining' is so grand at the 50-year level it's still a centerpiece of it all. The Seaport-BBY connection relies on it, the Urban Ring indirectly relies on it (esp. if only the north half can go LRT and the south half's lack of grade separation requires BRT and enhanced number of 'spoke' rapid transit intersection points), growth along that corridor-proper relies on it.

But it's a marathon, not sprint build that probably gets done in 3 or 4 separately funded independent chunks. Huntington trunk isn't in Kenmore's catchment area and doesn't do anything directly for the explosive Kenmore/Fenway-proper growth other than reshape Central Subway traffic away from it. And because it's a multi-phase, multi-decade build in pursuit of a far-reaching master plan that Kenmore-proper relief is going to be slow-developing. You will have a couple hairy decades of congestion growth to slog through before enough pieces of 'reimagined' Green are incrementally tied together to start providing waves of relief.


So there is something to be said for a one-and-done, relatively rapid build at sub-megaproject cost that has the whip cracked at it on construction schedule by the Storrow elimination leading it by the nose and setting its value judgment. I wouldn't lump it in with Huntington as an either/or because you're talking very different things driven by very different reasons on very different timetables. They'd exist on the same 2D system map with associated traffic shaping, but add a 3D "z = rationale" axis to it and they're not even close to touching.

'Riverbank Redux' I would say is time-specific like the original Riverbank was. The original was front-burnered for specific reasons when the BTC was deciding what it's Nineteen-aughts specific first-priority expansions would be. It fell away in priority after that deck got reshuffled, different expansions took priority, and those different expansions blunted enough of the edge off Riverbank's priority for it to slowly fade out. The revival would be similar: if de-Storrowing hits critical mass much sooner than you can physically do the separate pieces of the marathon-build Huntington spine, then you have to seriously consider something that can be put on the table in a single immediate build. If Huntington gets front-burnered much sooner such that some pieces (Seaport-BBY connector first off) are under design-build when de-Storrowing momentum hits critical mass, then you have a more realistic shot at muscling some megaproject money to get another big leg or two of it complete. And Riverbank once again gets demoted to second-division "nice-to-have / surplus-to-requirement" and stays way down the priority list, probably never to resurface.

So timing is crucial. We won't need to live with a big smelly induced-demand choked parkway if the infrastructure to sidestep it can/will be there in 7-10 years via Pike improvements and the rest is just 1-2 decades of wait acclimating Bostonians to overcoming their fear of roadway removal. But removing Storrow would almost certainly require a Back Bay-specific transit trade-in as an ironclad requirement. You can't build a time machine to airlift the completed Huntington spine through when it's going to take a quarter century at best case to build all the multiple phases to completion, and there's no reason to stick our grandchildren with a smelly parkway generations longer than it needs to be there in wait for this alt-spine megaproject to wrap. So...what's the fairest thing you can negotiate when the decision to remove the parkway is defined by a discrete time limit and there's no way the other stuff can be ready within that time?


Maybe the final answer isn't Riverbank, and the Redux fades into history like the original. But you definitely give it deadly serious consideration as one of your featured study alternatives when hashing out all the de-Storrowing who/what/when/where/why's.

 

[Transitmass]

I've been reviewing this thread and there is a topic we touched upon that I was wondering if we could look into again. We've talked about connecting the green line to the South Boston Transitway by re-using the Tremont Street tunnel and then doing an around the horn connection (what has been referred to as the Bay Village alignment).

F-Line has one concept of what the alignment would be which can be seen below (as re-posted by BussesAin'tTrains see post #52):

http://i.imgur.com/AkbWIGO.png

Davem had a different alignment which he outlined below (see post #53):

https://farm8.staticflickr.com/7596/16990954555_c8b20e5f21_b.jpg

My question is what is likely the most viable way to connect the green line to the South Boston Transitway assuming you are using the Bay Village Alignment (i.e. not connecting the green line by muscling the green line down Essex street itself)? Is the best way up Hudson St. as F-Line delineates or is it through the highway spaghetti bowl as Davem outlines? Also, if one could utilize elevated rail in order to make this connection then how would that change things?

We kind of get hung up on this point when discussing this idea but I wonder we could take a look at it again.

 

[George_Apley]

Here is what F-Line told me in a private message some time ago:

I can't find the schematic on GIS, but it's been posted in one of these threads before. Dave's correct...the loop is under Atlantic Ave. on the Essex St.-East St. block. Tunnel follows the street grid exactly; Silver platform's on Summer, then it hangs a left onto Atlantic. Loop spreads across the footprint of the start of the taxi stand and plaza at the Atlantic Ave. commuter rail entrance, and across the street under that conspicuously wide sidewalk in front of Dunkies.


The hook-in for a tunnel extension is at the corner of Atlantic & Essex slicing diagonally under the little concrete plaza at the front door of One Financial Plaza. So they're on separate alignments to give a SL vehicle either/or choice of heading westbound to the Back Bay in the finished tunnel or short-turning at SS by peeling out on the loop. With a combo light rail + bus Transitway that would just mean all buses loop and all trolleys continue on, and Essex/One Financial @ Atlantic is the end of shared-use portion of the tunnel.


Essex St. from Atlantic to the corner of Surface Rd. and north tip of Chinatown Park is the reserved alignment for any tunnel. One Financial was built to gut the innards of that ultra-wide Essex block for trouble-free tunneling that slips safely under I-93, etc. There is nothing under there now, but that is the one and only injection point into the Transitway so all build scenarios must tunnel on 750 ft.'s worth of Essex between the north tip of Chinatown Park @ Surface and the Transitway split @ Atlantic/One Financial. It's points south or west of that Chinatown Park tip where different alignments are still in play: the canceled SL III alignment under Essex/Boylston, or the South End jog through Chinatown Park, Hudson St., and Marginal St. But this right here is the ground zero where any/all of those alignments must meet: http://goo.gl/maps/qtx0W. You can see the reason why that tip and the ultra-wide plaza in front of One Lincoln are so conspicuously shaped. That's where any of the fudge factor in differing tunnel alignments squares itself for the locked-in final trajectory under I-93/Surface to Atlantic/One Financial and the Transitway.


That's probably where the confusion is. The loop isn't the continuation of the tunnel...it's a separate 250 ft. turnout that'll always remain there after they graft on the Phase III tunnel. And any permutation of the Phase III tunnel is locked onto the Essex alignment for those last 2 blocks to Atlantic, which is why the tip of Chinatown Park (and how one arrives there) is so important.

So it seems that, while Dave was indeed correct about the location of the loop, that was not the studied and planned for location of the connection for SLIII and presumably not for a GLX - which would be sited under the intersection adjacent to Chinatown Park.

I also remember someone (winstonoboogie perhaps) suggesting that the CA/T would complicate any attempt to reach the bus loop from the surface in the direction of the spaghetti.

 

[F-Line to Dudley]

I've been reviewing this thread and there is a topic we touched upon that I was wondering if we could look into again. We've talked about connecting the green line to the South Boston Transitway by re-using the Tremont Street tunnel and then doing an around the horn connection (what has been referred to as the Bay Village alignment).

F-Line has one concept of what the alignment would be which can be seen below (as re-posted by BussesAin'tTrains see post #52):

http://i.imgur.com/AkbWIGO.png

Davem had a different alignment which he outlined below (see post #53):

https://farm8.staticflickr.com/7596/16990954555_c8b20e5f21_b.jpg

My question is what is likely the most viable way to connect the green line to the South Boston Transitway assuming you are using the Bay Village Alignment (i.e. not connecting the green line by muscling the green line down Essex street itself)? Is the best way up Hudson St. as F-Line delineates or is it through the highway spaghetti bowl as Davem outlines? Also, if one could utilize elevated rail in order to make this connection then how would that change things?

We kind of get hung up on this point when discussing this idea but I wonder we could take a look at it again.

Pike WB loop ramp gets fouled by dave's routing and the number of South Bay bridge pilings is a nightmare. Is that one physically possible? Maybe...but it'll be a construction nightmare and way more costly.


My alignment isn't accurate to the last inch. You can swing out on a somewhat wider curve @ Curve St. by continuing that sideways dig through the highway retaining walls using the Pike ramp and that useless little grass median to keep a wide berth around the apartment tower on Hudson. Then from there center it under the roadway on Hudson. Not gonna lie...Hudson on the block prior to + block after Kneeland Street is going to be delicate digging with those tall buildings. It is absolutely wide enough sidewalk-to-sidewalk to do a cut-and-cover 2-track tunnel, but it will require careful mitigation on that 500 ft. stretch.

However, consider that Essex St. is even narrower in sections than the narrowest part of Hudson...by several feet. It has tall buildings framing its entire 1500 ft. length to Boylston. And this is where they were going to dig Silver Line Phase III cut-and-cover with an even wider bus tunnel, and somehow stick a station around Washington St. where the road is a few feet narrower than Hudson. Suddenly that hand-wringing about 1-1/2 blocks of Hudson doesn't sound so daunting, does it? It's feasible, and it is the most limited area of closely-abutted tunneling of any of the available options (including the ones where you're dodging dozens of South Bay ramp pilings). So that's why I sided with that one as best overall chances, pending a study.

Chinatown Park is where the space widens out; you just need to steer to the outside of the I-93 tunnel wall as you go through the park and descend to Essex St. at the same level as Silver Line Phase III would've gone. Then the 600 ft. down Essex to Atlantic is a Big Dig-era nuke job with cleanroomed under-street utilities and building foundations pre-built with the tunnel in mind. Merge into the Transitway would cut across the little plaza in front of the One Financial Center plaza, and the bus loop would remain a bus loop. If that turn was supposed to be A-OK--if slow as hell--on a 60-ft. articulated bus, it won't be cumbersome or all that slow at all on a trolley.





Back by Tremont/Shawmut it's negotiable what configuration you take. None of that's all that tricky because it's a 1960's urban renewal nuke zone and everything is set back from the street pretty far. Just take into account that 1) Tremont Tunnel is at very shallow depth dozen feet or less below street level when it dead-ends in Eliot Norton Park right around where this fenced-in garden is; 2) there's a need to incorporate some sort of intermediate station around here that can tie into Tufts Medical Center on Orange inside fare control through some sort of long walkway across the block; and 3) you have to cross under the fairly deep Orange Line tunnel at a minimally-invasive 90-degree angle when you cross it, and have a fairly stiff incline down on the ⅔ block before Marginal to get from shallow to deep.

Therefore your spacing of old tunnel<==>station<==>OL tunnel<==>South Station alignment across those 2+ blocks from the park to the Pike has to take into account changes in depth and appropriate spacing of structures relative to those changes in depth. i.e. Don't space the station too closely to where you have to dip down steeply before the Orange tunnel, and be careful where you space any junctions or provisions for future junctions relative to that incline down because of the steepness of the incline. You can waste a shitload of money trying to be way too precious about small placement details for the sake of perfection on a 2D map. Given how expensive this project is to begin with you do not want to be wasting money on this relatively easy block if that jeopardizes the whole project from getting built in the first place. If that means your provisions for a future connecting subway to Back Bay are less perfect for unassailable operational 'elegance'...so be it.

 

[Scalziand]

How close does the CAT go to the foundation of the Lincoln Plaza building on the corner of Lincoln and Essex? Lincoln is much wider than Hudson, and might make an acceptable alternative. It would be nice to not have to dive under the CAT like the Hudson route would.

https://www.google.com/maps/d/edit?mid=zkzO6ChGpVHo.kvGEiffxd2Rg&usp=sharing

 

[F-Line to Dudley]

How close does the CAT go to the foundation of the Lincoln Plaza building on the corner of Lincoln and Essex? Lincoln is much wider than Hudson, and might make an acceptable alternative. It would be nice to not have to dive under the CAT like the Hudson route would.

https://www.google.com/maps/d/edit?hl=en&hl=en&authuser=0&authuser=0&mid=zkzO6ChGpVHo.kvGEiffxd2Rg

I can't see the map since it's asking for a login. If you're saying swing +1 blocks out instead and ride Lincoln instead of Hudson you slam straight into a tunnel wall before reaching the corner of the building at Essex. And then the next block past Essex to Summer is blocked by 1) the Exit 20 collector/distributor tunnel off to the side underneath Lincoln St. Green, and 2) the Red Line under Summer St.

Unless you're attempting davem's routing around the South Bay minefield the only injection point across between Kneeland and Summer is Essex from the tip of Chinatown Park. There is no give whatsoever on those 3 blocks, and no give anywhere north of Essex. Just be thankful there's more than one trajectory for reaching that tip of Chinatown Park in the first place.

Also...when you're talking 1-on-1 comparisons between streets with barely 5-10 ft. difference in width, you're within the margin of error that the actual-factual Phase III BRT tunnel needed to bake in for turn radius around the curves on Essex. Essex, which is narrower in parts than Hudson. So we're really, really overrating how big an issue that's going to be on a 2-track trolley tunnel. Slipping past exactly 500 ft. linear feet of street where buildings happen to frame both sidewalks at the same time isn't a tall order. That new building on the corner of Kneeland leaves a fatter foundation-to-foundation width than the Green Line in front of the Omni Parker House or the Tremont Tunnel the first 2 blocks south of Boylston.

 

[Scalziand]

Oops, forgot to make the map viewable. Yes, I had it tiptoeing through some of the spaghetti to get to Lincoln before slipping into Essex trying to do the shallowest tunneling possible. From what I can tell, Lincoln is a full 20' wider than Hudson. I do have to admit that the Hudson routing is looking better to me now, what with the undercutting of the CAT from Chinatown Park to Essex being pre-provisioned for.