Regional Rail (RUR) & North-South Rail Link (NSRL)

[F-Line to Dudley]

Re: North-South Rail Link

His one zinger: "the South Station expansion proposal is a 19th-century solution to a 21st-century transportation issue." Kapow! Zing! Windows still rattling in the corner office at Beacon Hill, no doubt... he also touched on his advocacy for Blue Line to Lynn/Salem, and commuter ferry to Seaport, but not nearly to the extent of NS Rail Link....

This is the proof that he absolutely has not done his homework. The tunnel footprint our Big Dig forefathers left us doesn't have the capacity to equal, let alone surpass, the current terminals' capacity. *Maybe* it's a treading-water lateral move by the magic of running-thru, but the tunnel grades are so steep it's going to be a very slow crawl--especially for the partially un-electrifyable lines that have to run piggish push-pulls instead of EMU's--that capacity gets chewed back to no better than par. And potentially a little worse than par. There's no way to tart that up; it's a steep, steep ride through a fixed space.

The limiter...Seth...is also not the @#$% "19th century" surface terminals. It's the north and south interlockings where everything mashes into the terminals. Guess what...in a tunnel you get exactly the same north and south interlockings mashing exactly the same lines in exactly the same places! But with fewer tracks and steeper grades. Tell us, Seth, what century we're in and why what century we're in matters here.

The only way to unlock the system's true capacity is by doubling capacity at these north & south mashups. A pick-'em of upstairs/downstairs Tower 1 interlocking on the northside and upstairs/downstairs Cove interlocking on the south side. Then shoot 'em full at double barrels--*pew-pew! pew-pew!*--with total frequencies the likes of which make the Germans exclaim "You magnificent bastards!" And yes...our magnificent-bastarding of the first world is going to require healing the scars at what was lopped in half 50 years ago at South Station.


Frequencies and frequency limiters aren't a difficult topic to grasp. Vet harder, Seth. Maybe sample some opinions from pol advocates who've actually held office within the last 25 years and don't have an axe to grind about buildings renamed against their will.

 

[whighlander]

Re: North-South Rail Link

Well, for very obvious reasons--despite his glittering war record and overall conspicuously overachieving/prestigious resume, he remains a junior junior Congressman for the minority party. I'm just intrigued at how the machinations between his and Baker's office will play out on this ongoing NSRL vs. South Station expansion battle. It's just catnip for mass transit policy wonks, I'm sure...

P.S. A cursory review of the MBTA commuter rail system map overlaying Mass. congressional districts map makes me think Moulton has more commuter rail stops, by a fairly comfortable margin, than any of the other MA Congressional reps. All of Newburyport/Rockport line north of Chelsea, all of Lowell line save Lowell, all of Haverhill line save Lawrence & Haverhill (as best I can judge). But again, that's just a long glance...

DBM -- you could almost say that because of the election that neither man is really in strong position to influence what happens in Washington. Moulton because as you said he's a jr of the minority. Baker because while in principle he's a key governor from the Majority party -- he didn't exactly line up with the president-Elect. Baker does have one still good connection that would be that both he and VP-Elect Pense were members of the Republican Governors association

Otherwise -- Maybe Karen Polito can be the liaison via Reince Priebus -- Chief of Staff designate to the President-Elect

 

[whighlander]

Re: North-South Rail Link

This is the proof that he absolutely has not done his homework. The tunnel footprint our Big Dig forefathers left us doesn't have the capacity to equal, let alone surpass, the current terminals' capacity. *Maybe* it's a treading-water lateral move by the magic of running-thru, but the tunnel grades are so steep it's going to be a very slow crawl--especially for the partially un-electrifyable lines that have to run piggish push-pulls instead of EMU's--that capacity gets chewed back to no better than par. And potentially a little worse than par. There's no way to tart that up; it's a steep, steep ride through a fixed space.

The limiter...Seth...is also not the @#$% "19th century" surface terminals. It's the north and south interlockings where everything mashes into the terminals. Guess what...in a tunnel you get exactly the same north and south interlockings mashing exactly the same lines in exactly the same places! But with fewer tracks and steeper grades. Tell us, Seth, what century we're in and why what century we're in matters here.

The only way to unlock the system's true capacity is by doubling capacity at these north & south mashups. A pick-'em of upstairs/downstairs Tower 1 interlocking on the northside and upstairs/downstairs Cove interlocking on the south side. Then shoot 'em full at double barrels--*pew-pew! pew-pew!*--with total frequencies the likes of which make the Germans exclaim "You magnificent bastards!" And yes...our magnificent-bastarding of the first world is going to require healing the scars at what was lopped in half 50 years ago at South Station.


Frequencies and frequency limiters aren't a difficult topic to grasp. Vet harder, Seth. Maybe sample some opinions from pol advocates who've actually held office within the last 25 years and don't have an axe to grind about buildings renamed against their will.

F-Line -- Well done -- a great summary of the issues which are or should be at the core of the discussion

 

[DBM]

Re: North-South Rail Link

This is the proof that he absolutely has not done his homework. The tunnel footprint our Big Dig forefathers left us doesn't have the capacity to equal, let alone surpass, the current terminals' capacity. *Maybe* it's a treading-water lateral move by the magic of running-thru, but the tunnel grades are so steep it's going to be a very slow crawl--especially for the partially un-electrifyable lines that have to run piggish push-pulls instead of EMU's--that capacity gets chewed back to no better than par. And potentially a little worse than par. There's no way to tart that up; it's a steep, steep ride through a fixed space.

The limiter...Seth...is also not the @#$% "19th century" surface terminals. It's the north and south interlockings where everything mashes into the terminals. Guess what...in a tunnel you get exactly the same north and south interlockings mashing exactly the same lines in exactly the same places! But with fewer tracks and steeper grades. Tell us, Seth, what century we're in and why what century we're in matters here.

The only way to unlock the system's true capacity is by doubling capacity at these north & south mashups. A pick-'em of upstairs/downstairs Tower 1 interlocking on the northside and upstairs/downstairs Cove interlocking on the south side. Then shoot 'em full at double barrels--*pew-pew! pew-pew!*--with total frequencies the likes of which make the Germans exclaim "You magnificent bastards!" And yes...our magnificent-bastarding of the first world is going to require healing the scars at what was lopped in half 50 years ago at South Station.


Frequencies and frequency limiters aren't a difficult topic to grasp. Vet harder, Seth. Maybe sample some opinions from pol advocates who've actually held office within the last 25 years and don't have an axe to grind about buildings renamed against their will.

Forgot to mention perhaps the most interesting aspect of Moulton's stumping for NSRL in Nahant yesterday--that he tried to placate any anxieties by saying, "folks: this isn't going to be like the Big Dig. The Big Dig was so expensive and disruptive because it was a top-down intrusion. With the tunnel boring machines these days, they'll be able to just bore right through."

A few thoughts:

1.) To a crowd of elderly Nahanters--many of whom would've been doing battle with the northside Big Dig, driving down 1A while commuting to Boston in the 1990s--conjuring up the big bad Big Dig is probably good political theater.
2.) But the Big Dig is also obviously a sui generis.
3.) So it's a bit of a red herring, isn't it, to juxtapose the potential project that is NSRL to a completed massive infrastructure project... when the only thing they share in common is general locale/geologic strata.

Anyway, it'll be interesting...

 

[F-Line to Dudley]

Re: North-South Rail Link

Forgot to mention perhaps the most interesting aspect of Moulton's stumping for NSRL in Nahant yesterday--that he tried to placate any anxieties by saying, "folks: this isn't going to be like the Big Dig. The Big Dig was so expensive and disruptive because it was a top-down intrusion. With the tunnel boring machines these days, they'll be able to just bore right through."

A few thoughts:

1.) To a crowd of elderly Nahanters--many of whom would've been doing battle with the northside Big Dig, driving down 1A while commuting to Boston in the 1990s--conjuring up the big bad Big Dig is probably good political theater.
2.) But the Big Dig is also obviously a sui generis.
3.) So it's a bit of a red herring, isn't it, to juxtapose the potential project that is NSRL to a completed massive infrastructure project... when the only thing they share in common is general locale/geologic strata.

Anyway, it'll be interesting...

Probably the tactic every pol's going to use.


There will be surface disruption at North Station and South Station for the station caverns and for slotting those cavern tunnels on/off the I-93 footprint. No real building impacts, and any traffic blocks affected aren't load-bearing. So the number of properties that'll need Big Dig-style mitigation for construction disprution at their doorsteps, extended construction hours, construction vibrations, and traffic disruptions are single digits instead of 2 blocks deep on all sides of a mile-long project area like the Big Dig. And since these are mainly new buildings and not the Big Dig task of keeping some very old North End brick buildings from shaking to death...much less intensive and shorter-lived impacts. Most of the buildings in question were also built after the NSRL Major Investment Study, so the developers knew long before ground was ever broken that this had probability of happening. It's one of the reasons why the real estate value shot up so much around SS and NS for erecting those buildings in the first place, so I doubt there'll be much sweating.

To the south. . .

• The Summer-Congress block of Dot Ave. is probably going to be out-of-commission for awhile.
• The Harborwalk and rear-facing plazas at Atlantic and Independence Wharves will have to be sacrificed to construction staging and boring holes for the approach to the station cavern. Though they will be completely reconstructed afterwards. Channel recreational boating semi-disrupted (though the Seaport side will be fine if they just cordon off the middle of the water with buoys spanned by rope to keep people away from the construction site).
• Approx. 1000 ft. of Ft. Point Channel retaining wall from midpoint of current USPS to Congress/Atlantic Wharf will be underpinned and partially replaced, since the tunnel straddles deep under Dot Ave. and that end of the Channel. Will probably see some long linear drydock do up on that side of the Channel so they can access below, and view out the ground-floor windows of the northernmost post-USPS row buildings on Dot Ave. obscured by scaffolding (but probably not much actual traffic/access disruption in front of those buildings).
• Big-ass cranes next to the Summer, Congress, and Moakley bridges and occasional days where traffic cones will appear blocking right lanes and one of the sidewalks while they're loading something large in the bucket to take into a borehole.
• Some transient lane closures on 93N when they're punching small holes through the wall to snake utilities.
• Some designated truck routes from Haul Rd. for getting materials to the bore holes. Probably a lot of nocturnal activity since nobody lives immediately along the Channel.

Up north:

• Bunch of temporary disruption to the 2 blocks bounded by Causeway St.-New Chadron and Canal St.-Beverly St. where the tunnel comes off 93 and goes into the terminal cavern. Some "Pardon Our Appearance" side street closures, but a lot more limited and more benign than by South Station.

*Maybe* if the increasingly unlikely Central Station forces a widening-out of the bore around Long Wharf you'll need a borehole there in the Aquarium plaza. But that's probably another strike against doing a station here at all.




Everything else is scooping out under 93 where no one on or abutting the Greenway or driving 93 will ever know there's a megaproject going on beneath their feet. And all of the lead tunnels are square underneath existing MBTA commuter rail tracks in the Pike cut, through the Southampton wasteland of CR, Amtrak, and Red Line facilities, and under Leverett Connector by Boston Engine Terminal. It is mainly that very tough South Station cavern that straddles the Channel and insertion point from the water into 93 that are going to be a little fugly for a few years. That segment is more expensive than the actual scoop-and-finish under 93 where the biggest chunk of tunneling feet is, and you can see why as it's the only portion with any significant surface disruption. But it's not a lot of surface disruption in the grand scheme or particularly intensive disruption, it doesn't affect Atlantic Ave. at all where the main surface traffic goes, and the pure commercial occupancy there makes 24/7 construction non-disruptive so they can move twice as fast as any other project that would have to pause on the overnight and mess traffic up harder during the day for the sake of abutters' sleep.


Yes...that's a lede small enough to easily bury and pitch "NOT BIG DIG II" to concerned citizens.

 

[orulz]

Re: North-South Rail Link

Hi all, new here but wanted to add 2 more cents to the discussion.

I would not dispute anything that F-line says about South Station and North Station both needing above-ground expansion in addition to the NSRL. However, descriptions of the South Station project mention that it is "not to preclude" future construction of the proposed rail link, which sounds like some pretty bare-bones, sub-optimal accommodations to me.

Even though the Big Dig was likewise built "not to preclude" the Rail Link, it probably would have been cheaper and easier in the long run to go ahead and build the rail link at the same time as the Big Dig highway project. I'd hate to compound that problem and give more fodder to NSRL opponents.

Therefore, it seems to me that this is the time to get buy in that the NSRL is definitely going to happen at some point, and then go ahead and design it now - get it up to 60% design or something, figure out what cavern is necessary for the South Station on the NSRL, design the South Station expansion as a cohesive whole, including both above-ground and underground elements, and then go ahead and build it! At the very least, build a shell of the cavern for the underground station. Something along the lines of the Tunnel Box under Hudson Yards in Manhattan, or the Transbay Terminal in San Francisco, or whatever. (Those projects both have their issues, to be sure, but I'm talking about the concept here, not the execution.)

 

[F-Line to Dudley]

Re: North-South Rail Link

Hi all, new here but wanted to add 2 more cents to the discussion.

I would not dispute anything that F-line says about South Station and North Station both needing above-ground expansion in addition to the NSRL. However, descriptions of the South Station project mention that it is "not to preclude" future construction of the proposed rail link, which sounds like some pretty bare-bones, sub-optimal accommodations to me.

It means exactly what they say it means: nothing is going to be allowed to ruin NSRL. There is a set trajectory to the NSRL under Dot Ave. constrained by the Big Dig tunnels and Red/Silver tunnels it has to slot around, with the Channel and adjacent buildings leaving a finite-size cavern for the underground station. It's actually not on the surface station's footprint at all, but on the new row of Dot Ave.-facing buildings. So it's that brand new mixed-use development parcels that SSX is leaving behind after the Post Office is demolished that are specced to not have their foundation pilings breach the tunnel level or preclude underpinning.

No compromises. They levied that on any potential developers for that new commercial space because they don't want a private construction brain-fart to senselessly murder the NSRL forever. And they know they can't trust the BRA to police this, so the state approves the piling depth for these buildings.

Therefore, it seems to me that this is the time to get buy in that the NSRL is definitely going to happen at some point, and then go ahead and design it now - get it up to 60% design or something, figure out what cavern is necessary for the South Station on the NSRL, design the South Station expansion as a cohesive whole, including both above-ground and underground elements, and then go ahead and build it! At the very least, build a shell of the cavern for the underground station. Something along the lines of the Tunnel Box under Hudson Yards in Manhattan, or the Transbay Terminal in San Francisco, or whatever. (Those projects both have their issues, to be sure, but I'm talking about the concept here, not the execution.)

You don't need to shotgun it all because, as above, the surface expansion is not on the tunnel footprint...the post-SSX new commercial development is. They do need to start a new EIS for NSRL, but considering that nothing whatsoever has happened since the Major Investment Study it's going to be 20 years minimum of studying, lobbying, gov't action to go for it, and then design paperwork paperwork paperwork before first shovel goes in ground. And it's going to take awhile at SS Under because that's the most complex by far piece. We aren't talking East Side Access-level intensive, but it's a solid 5 years of cumulative construction deep under the bowels of the city on top of that 15-20 years of paper-pushing. We're still that far behind.

SSX is shovel-ready the second USPS relocates. The trackwork itself is fixed-cost, so the only money concerns they're kvetching about is whether they can build the headhouse and put Dot Ave. out to bid immediately or if they're going to have to do bare functioning platforms while they reload the budget for the niceties. Get this show on the road with USPS and the trains part of SSX can probably be open in late-2020 to mid-2021, 4-5 short years from now.

SSX is also not just about platform capacity. The station used to be completely symmetrical in its original configuration, making it easy to distribute trains at the mash-up of switches without conflicting cross movements. When it got lopped in half in the 60's the crippled half-station had to skew all the switches hard towards the NEC side leaving lots of conflicting movements from due south. That was A-OK when there was no Old Colony of Fairmount commuter rail to worry about, just the layover yard. Now it's a real problem because lines (especially NEC vs. the world) have to cross up each other to fan out. It imposes a nasty cap on train movements, bottles up equipment on the platforms, and limits slots into the layover yard. Amtrak makes it worse because they HAVE to deadhead to the layover yard after every run to change crews, restock food service, etc. Meaning the T is really out of options for muscling equipment.

The regained capacity has little to do with the extra platforms, and everything to do with the regained symmetry in the traffic distribution (or 80% of the symmetry of old). You need the extra platforms so the NEC cross-cut movements no longer block the branchlines or the Old Colony or anyone's dreams of running Indigo trains every 15 mins. down the Fairmount. It's not a big meal of platform calories. It's fixing what was broken at the switches so there's no more traffic conflicts. To do that and re-establish that symmetry you need to fling stuff further out to Dot Ave. on new platforms. But the capacity gained is ALL about the eliminated conflicts. That in a nutshell is why SSX is non-optional, and why SSX has absolutely nothing nothing whatsoever to do with NSRL.


These are the talking points for the Seth Moultons of the world to get it in their heads:

• SSX: Fix what we broke. No more traffic conflicts = capacity!

• NSRL + SSX/NSX: Our magnificent bastarding of first-world service levels. If the mash-up of lines in the terminal district is the system's service limiter, make two separate upstairs/downstairs terminal districts and double-barrel them. TWICE the capacity!...100-year solve! Put them in competition with each other...same limiter (or worse) downstairs as the one you gave up upstairs. Why tread water?

• NSRL + not-SSX: Not only are they not within 2 decades of each other on shovel-ready, but if we are going to magnificent-bastard the Germans with twice the service levels, those cross-cut conflicts upstairs are going to be a pain in the ass all the same. Especially because 2040's superduper Acela service levels are probably still going to be stopping upstairs while only NE Regionals run underground. And those superduper Acela schedules will bogart a lot of platforms and force a lot of cross-cut conflicts. You will end up non-optionally building SSX anyway when NEC FUTURE comes to town, for the same reasons of fixing a broken traffic mgt. thing...only it'll cost twice as much as today. Why wait? It's the conflicts, not the platforms. We don't get saturation-level Acelas without fixing what was broken.

Make sense?

 

[orulz]

Re: North-South Rail Link

Have they already worked out how the underground portion of South Station will tie into the existing SS and SSX? ie, systems such as escalators, elevators, utilities, ventilation, emergency egress, etc. Would hate to wind up in a situation where they have to un-build a significant amount of the work they're about to do. If they could figure that out to a point where they can just put in some knock-out panels in the walls or leave an extra, empty utility room somewhere within the complex, that could potentially save $$ in the future.

Also it seems to me like it would be easier, cheaper, and less risky to build the NSRL station cavern with nothing over the top of it, than with new mixed use buildings over the top of it. Even given that said mixed use buildings are planned to be built such that their foundations are deep enough to not directly interfere with the cavern itself. Now, I don't mean risky in terms of "building collapse, people gonna die" but more in terms of "moderate unexpected subsidence leading to extra costs and schedule overruns".

I am raising the point due to this: There is still a lot of denialism and skepticism over the need for NSRL, and subsequently still plenty of opposition to spending any money, present or future, on planning for or building the NSRL. There are still plenty of people saying and believing that SSX by itself is good enough. Anything that can be done to undermine those interests as a part of the SSX project itself is a win to me.

So. Are you saying that the already planned accommodations for NSRL within the SSX project really are comprehensive and will make it so building NSRL will cost absolutely no more with SSX and its corresponding mixed use developments already in place, compared with building some extra accommodations at the same time? In which case, that's fantastic (but still a bit hard to believe). Or are you saying that these accommodations are all that can probably realistically be obtained without blowing SSX schedules and budgets out of the water? Or is there room to do more if all trace of NSRL skepticism is removed from the planning process?

 

[F-Line to Dudley]

Re: North-South Rail Link

Have they already worked out how the underground portion of South Station will tie into the existing SS and SSX? ie, systems such as escalators, elevators, utilities, ventilation, emergency egress, etc. Would hate to wind up in a situation where they have to un-build a significant amount of the work they're about to do. If they could figure that out to a point where they can just put in some knock-out panels in the walls or leave an extra, empty utility room somewhere within the complex, that could potentially save $$ in the future.

Also it seems to me like it would be easier, cheaper, and less risky to build the NSRL station cavern with nothing over the top of it, than with new mixed use buildings over the top of it. Even given that said mixed use buildings are planned to be built such that their foundations are deep enough to not directly interfere with the cavern itself. Now, I don't mean risky in terms of "building collapse, people gonna die" but more in terms of "moderate unexpected subsidence leading to extra costs and schedule overruns".

I am raising the point due to this: There is still a lot of denialism and skepticism over the need for NSRL, and subsequently still plenty of opposition to spending any money, present or future, on planning for or building the NSRL. There are still plenty of people saying and believing that SSX by itself is good enough. Anything that can be done to undermine those interests as a part of the SSX project itself is a win to me.

So. Are you saying that the already planned accommodations for NSRL within the SSX project really are comprehensive and will make it so building NSRL will cost absolutely no more with SSX and its corresponding mixed use developments already in place, compared with building some extra accommodations at the same time? In which case, that's fantastic (but still a bit hard to believe). Or are you saying that these accommodations are all that can probably realistically be obtained without blowing SSX schedules and budgets out of the water? Or is there room to do more if all trace of NSRL skepticism is removed from the planning process?

Either of the potential alignments--Dewey Sq. (non-preferred...all but eliminated) or Dot Ave./straddling the Channel (almost certain)--are well offset from the surface station, so there would be no disruption. The Dot Ave. alignment is also deep enough underground that the new street-facing row buildings won't have pilings anywhere deep enough to require mitigation efforts. Tradeoff: modest height limit (probably not gonna see >8-10 stories) facing the street...though with the air rights tower going in right behind it that's a moot point because aesthetically nobody would want to block the lower floors of the tower in darkness with something too tall 50 ft. away. Any greenlit developments will need to conform to do-no-harm guidelines for the foundation pour and have that piece approved by the state before being approved, so zero chance that the tunnel alignment will be blocked by a developer or BRA/BDPA brainfart. But other than that there's nothing with SSX or its redev coattails that need to make any preparations whatsoever for NSRL. The surface train station isn't on the tunnel footprint, and the depth difference between surface buildings and tunnel is so huge that it doesn't matter.

The hook-in from those very deep escalators would be the Red/Silver Line mezzanine and not the main station, because that large rapid transit lobby covers most of the block and aligns pretty well for elevators and escalators from the offset station. On either the Dot Ave. or Dewey alignments. So switching surface to underground means going through the same concourse you go through today to switch to rapid transit. Helps that the existing mezzanine is so oversize for what foot traffic it handles; they won't need to make any substantial mods to it.



They'd gain nothing by doing an empty shell now because it's too far down to dig a straight hole from the surface to begin with. You're thinking cut-and-cover. This is 50-75 ft. below the practical limits of cut-and-cover. Same level the Blue Line is when it's in the middle of the Harbor...only this is where the station is going to go. So a moot point because it's technically impossible to dig a Really Big Hole™ straight down under Dot Ave. 20 paces from the adjacent Ft. Point Channel. Tunnel's strictly the realm of a TBM machine that gets inserted underground way over on the other side of the Bass River by the Red Line yard and chews through 2000 ft. of earth before ever reaching the spot where the station cavern gets hollowed out. No one eating lunch on a patio at one of those post-SSX Dot Ave. row buildings will ever know there's a major construction project going on 100 ft. below them...except for some boreholes on Summer St. for the elevator/escalator shafts and some reworking of the Channel retaining wall for waterproofing at point the escalator shafts come closest to the water. There's no savings in going to the trouble of bringing in the heavy artillery of a TBM machine, digging diagonally a third of a mile to even reach the station location in the first place, pack up shop and leave it a stub-end shell...then bring the TBM back all over again years later and finding a way to reassemble it inside the shell. The economics of a TBM are meant for one-and-done (or one TBM per tunnel end-half, and done)...not the installment plan. It'd be pointless double-dipping on costs for zero net gain to start then stop, especially when there's no surface dependencies to begin with.

 

[Arlington]

Re: North-South Rail Link

Could a NSRL station deep under Dot-Ave/Channel actually get escalators that reached all the way to the Boston Wharf Co side? That'd be a sweet little boost for Seaport access.

 

[F-Line to Dudley]

Re: North-South Rail Link

Could a NSRL station deep under Dot-Ave/Channel actually get escalators that reached all the way to the Boston Wharf Co side? That'd be a sweet little boost for Seaport access.

No, never, not even close.

1) It's not nearly that close to the Seaport side. The Channel's a full 500 ft. wide here, and the station is doing little more than dipping its toes on that side of the retaining wall.

2) The Red Line tunnel is way out in the middle of the Channel up above NSRL in this spot making a wide swoop onto the footprint of Summer St., so there's structural impacts to trying to dig a shaft in that direction.

3) Part of the reason the tunnel is so far underground is that they don't have to engage the water in the Channel at all. By unidirectionally shafting the egress towards the Dewey Sq. mezzanine they'll be 100 ft. inland before they get close to the bottom depth of the Channel and all construction boreholes to get into the egresses can be punched along the Summer St. plazas high and dry. Going the other direction requires drilling boreholes from barges in the middle of the Channel, then doing hellaciously expensive waterproofing to the shafts which will be much closer to the bottom of the Channel before they have first chance at popping up to a surface exit.

Suicidally expensive and overcomplicated for a very minor frill. There's no parallel universe where Seaport foot-traffic is going to be so thick and so overwhelms the sidewalks on the bridges where this would even get a nanosecond's consideration from the project engineers.

 

[Lrfox]

Re: North-South Rail Link

^^

 

[FK4]

Re: North-South Rail Link

Approved!!!





Jk

 

[whighlander]

Re: North-South Rail Link

Approved!!!





Jk

FK-- Quoi???

April Fools day is still months away -- so to what are you referring as being approved?

 

[F-Line to Dudley]

Re: North-South Rail Link

April Fools day. . .

^That was the intent of the prior 2 posts.

 

[orulz]

Re: North-South Rail Link

You're thinking cut-and-cover. This is 50-75 ft. below the practical limits of cut-and-cover. Same level the Blue Line is when it's in the middle of the Harbor...only this is where the station is going to go. So a moot point because it's technically impossible to dig a Really Big Hole™ straight down under Dot Ave. 20 paces from the adjacent Ft. Point Channel.

F-Line,

This is the meat of the answer I was looking for. For some reason, I thought the tunnels and station caverns for NSRL were going to be basically just below the floor of the big dig highway tunnels. Given that metro lines where tunnels are excavated by TBM and stations are excavated by cut/cover are fairly common, and given the not-so-deep depth of most of the Big Dig, I was thinking that approach might be possible here.

Thanks for clarifying that SS-underground will be so deep as to be below the practical limits of cut-and-cover.

 

[CSTH]

Re: North-South Rail Link

I'll quibble that it's hard to believe that it's literally technically impossible to do cut and cover at this depth and proximity to the channel. The artery was essentially dug to the same depth, width and distance @ james hook already, and we could name several other points in the artery tunnel that are too - the big dig of course was all giant cut and cover work.

I completely understand that if you have the TBMs running anyway for digging the lion's share of the route, then its a lot easier just to mine out the stations from within the TBM tunnel than to cut and cover them. (And the reasons why TBMs work for NSRL but not for big dig should be self-evident to this crowd).

But i'm skeptical that its literally impossible, or even that it would be pushing the envelope of feasibility. (Sometimes, F-line, i have a hard time telling when you mean "literally impossible (or 'would push the envelope of feasibility)", and when you might really just mean, "self-evidently a really bad option").

I mean, for the sake of argument - if NSRL were really big dig two, they would just cast the whole station out of steel at a shipyard in baltimore, then float it up and sink it in a temporary drydock under the USPS footprint (*sigh*)

And on a less-sarcastic-but-more-cynical-note....if they DID choose cut and cover, then there'd be an opportunity to fill 3-4 stories of parking (errr...'transportation center') between the platforms and the surface (like Amsterdam, incredibly, has done with some of the station on the nord-zuid line)

Plus, you're going to need a box to launch the TBM from anyway, and it's not clear that 'between the tracks and the pike' on the marginal st. corridor is a great option either (assuming they can even make the curve).

(/quibble)

 

[F-Line to Dudley]

Re: North-South Rail Link

By "literally impossible"...I mean that it is the stupidest, most stubborn, most expensive way of waging an argument against the whole of the field of civil engineering about what is the hardest physically possible means to build something that clings to the arse end of the thousandths place of feasibility to win meaningless "technically correct is the best kind of correct" bragging rights in a theoretical vacuum. I could not give two shits who wins a tougher-than-thou civil engineering strongman competition in fantasy land, or on another Crazy Transit Pitches sidebar that completely loses the plot on what the "Transit Pitch" is to indulge an id-driven tall building fetish gone subterranean.

In the 'literal' world...yes, that is impossible. Full-stop. The NSRL tunnel is not a fantasy concept. It has a comprehensive Major Investment Study on the books with two vetted alignments around South Station. It is a literal proposed and vetted build, not somebody's map doodle. Its slotting through the subterranean maze is well-documented from 25 years worth of real Big Dig design-build...including where it slots around the wholesale CA/T reshaping of the Channel at its South Bay end. The NSRL Alternatives officially on the books accomplish the project goals. The NSRL Alternatives officially on the books have already been pegged as the builds with the highest engineering feasibility of anything that'll be worth the cost of attempting at all. It's been spelled out in enough detail that "Why don't we leave the TBM home and just cut-and-cover a Really Big Hole™?" abstract questions are fully asked/answered: no, it'll never be worth the investment to do that. In the 'literal' world, it's already been determined that if that's how you want or have to roll...there won't be an NSRL. The cost/benefit will never wash and it would be far too irresponsible to proceed.

If some fatal blocker is laying in the weeds to upend the final engineering on the main alignment, there won't be a previously-vetted Alternative like the 40-year potpourri of alt. Silver Line Phase III BRT/LRT alignments sprayed all around Chinatown and South End to fall back on for a re-study. There's only one way to do the max-build NSRL: slot under 93 from mile-long lead tunnels at a set depth underground with set-dimension underground stations. There are two slotting Alternatives for SS Under: Dot Ave. offset, or Dewey Sq. offset (and odds have already been stacked way, way in favor of Dot Ave. on feasibility because of Fed Reserve building mitigation & other nasty project overhead on the Dewey side). And all else is just how many features you keep, cut, or defer within that max-build's footprint. When the tunneling properties are that spelled-out this far in advance it's not up to the imagination or fodder for high school debate-team whether you can cut-and-cover a Really Big Hole™ through the center of Dot Ave. because reasons. The dead trees the MIS is printed on already spell out what the only feasible Alternatives are: they involve one trajectory and TBM's. A Really Big Hole™ is already ruled out because the project wouldn't be sane to build at that cost: real-world infeasible, real-world impossible.

[/quibble-rant]


Jeezus...are we still having this much trouble here telling the difference between a Crazy Transit Pitch, an actual unfunded mandate, and a Crazy-without-the-Pitch acid fever???

 

[CSTH]

Re: North-South Rail Link

Ok!

Also, maybe its finally time to start a new 'Acid-Trip Transit Pitches' thread where we can all go back to talking about our crazy solipsistic technicolor hallucinations ... just for the fun of it?

 

[whighlander]

Re: North-South Rail Link

Ok!

Also, maybe its finally time to start a new 'Acid-Trip Transit Pitches' thread where we can all go back to talking about our crazy solipsistic technicolor hallucinations ... just for the fun of it?

I'm guessing that everyone on the ABForum interested in Crazy Transit Pitches is:
1) old enough
2) can either grow your own or ask a friend of a friend


So in the great tradition of the signs in the London Underground during the "Blitz"

I recommend that those interested in this topic

Light up a Bong -- chill out and well chill out some more

Carry On