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

[F-Line to Dudley]

Re: North-South Rail Link

If all 11-12 commuter rail lines are going to be passing through Boston this Rail Link is going to need a lot more than 2 tracks. It might need like 5-6 tracks like Back Bay in order to handle all those train routes.

Not all schedules are going to pass through it, exactly because of that reason. It doesn't increase capacity as a replacement for the surface terminals, because it would have the same traffic limiter: the interlockings that mash all lines together. Despite the advantages of run-thru ops it may even end up having slightly less overall throughput than the surface terminals because those same mash-ups of all lines will be happening at steep instead of level grades with greater speed restrictions TBD by the tunnel engineering.

Of course, no one (excepting the occasional pompous grifter like Seth Moulton) has ever claimed that NSRL would or should displace the surface terminals. The great service increaser that the project brings is the ability to filet service levels to "upstairs & downstairs" Tower A interlockings on the northside and "upstairs & downstairs" Cove & Tower 1 interlockings on the southside. When those mash-ups are the systemwide limiter, doubling them up effectively doubles the capacity of the whole system. Use all options to their fullest and we can have Amtrak 2040 Superduper HSR service levels, Regional Rail local frequencies beyond our wildest dreams, full commuter rail integration with NH and RI...and still won't exhaust all slack capacity. It's the 100-year solve for growth.

Of course, with those kinds of capacity ceilings in-play the value proposition is all about how you plan to use it...not the mere accomplishment of building it. Right now the messaging is hopefully confused because there's no agreement on exactly how NSRL would be used. Run-thru alone won't sell it when the service levels are a lateral trade. Somebody has to be able to articulate exactly how supersized our Regional Rail future is going to be and how those future service levels call for solving the system limiter of terminal district mash-ups with upstairs/downstairs interlockings. And take a gander at how the surface terminals and tunnel will interplay in daily service in a universe where that double-up of upstairs/downstairs mash-ups is the big capacity solve. What makes a good regular tunnel slot pairing? What in turn makes a good surface slot: surge service, longer-distance service, destinations better-suited to transfers than an even overchurn of ridership? And how do upstairs/downstairs slots juxtapose off each other to mutual benefit?


Right now the sides of the NSRL argument are talking in exclusion to that interplay. Including TransitMatters, who've unfortunately been goaded by the Admin's monolithic framing games into all-or-nothing opposition of SSX instead of breaking it into its constituent parts for separate examination. Such as: separating the pros/cons of the traffic conflict solves in the base-most SSX track work package from the larded-on politics of station house monument-building and real estate tug-of-war...because if you're going to be fileting terminals to maximize service levels you're still going to want freer movements on/off the platforms instead of having spiraling Amtrak traffic bottle things up with constant cross-cutting movements. Likewise: breaking out the pros/cons of the storage yard land acquisition from the faulty SSX-vs.-NSRL framing...as securing the Widett Circle parcel would not only secure all southside terminal storage needs today but has the flex to be reapportioned for bus storage to consolidate the downtown garages should NSRL reduce the number of trainsets that need downtown storage. Some of these bits and pieces are necessary to have in any universe...but especially one where the be-all/end-all goal is securing 100-year service level growth. Unfortunately the pressure to debate on the state's monolithic framing ends up losing some details in the noise.

Everybody's got a lot of improvement to make in sharpening up their talking points. TM is taking first stab at that with their best "It's the frequencies, stupid!" step forward about Regional Rail operating practices being the only NSRL prerequisite that matters, and something that must proceed today on the system we have in order for the tunnel to have any value proposition worth pursuing. It would be nice if the Dukakis/Weld NSRL advocacy went lockstep with that, but they still seem to want to spin their wheels pushing run-thru for run-thru's sake when that's a born loser of an argument detached from any compelling vision about baseline frequencies. Clean it up some more from there and the frequencies! frequencies! frequencies! argument has a dead-on natural segue to the doubling of terminal district capacity, with all the run-thru advantages as an accessory to that lead-in.

 

[DominusNovus]

Re: North-South Rail Link

Not all schedules are going to pass through it, exactly because of that reason. It doesn't increase capacity as a replacement for the surface terminals, because it would have the same traffic limiter: the interlockings that mash all lines together. Despite the advantages of run-thru ops it may even end up having slightly less overall throughput than the surface terminals because those same mash-ups of all lines will be happening at steep instead of level grades with greater speed restrictions TBD by the tunnel engineering.

Of course, no one (excepting the occasional pompous grifter like Seth Moulton) has ever claimed that NSRL would or should displace the surface terminals. The great service increaser that the project brings is the ability to filet service levels to "upstairs & downstairs" Tower A interlockings on the northside and "upstairs & downstairs" Cove & Tower 1 interlockings on the southside. When those mash-ups are the systemwide limiter, doubling them up effectively doubles the capacity of the whole system. Use all options to their fullest and we can have Amtrak 2040 Superduper HSR service levels, Regional Rail local frequencies beyond our wildest dreams, full commuter rail integration with NH and RI...and still won't exhaust all slack capacity. It's the 100-year solve for growth.

Of course, with those kinds of capacity ceilings in-play the value proposition is all about how you plan to use it...not the mere accomplishment of building it. Right now the messaging is hopefully confused because there's no agreement on exactly how NSRL would be used. Run-thru alone won't sell it when the service levels are a lateral trade. Somebody has to be able to articulate exactly how supersized our Regional Rail future is going to be and how those future service levels call for solving the system limiter of terminal district mash-ups with upstairs/downstairs interlockings. And take a gander at how the surface terminals and tunnel will interplay in daily service in a universe where that double-up of upstairs/downstairs mash-ups is the big capacity solve. What makes a good regular tunnel slot pairing? What in turn makes a good surface slot: surge service, longer-distance service, destinations better-suited to transfers than an even overchurn of ridership? And how do upstairs/downstairs slots juxtapose off each other to mutual benefit?


Right now the sides of the NSRL argument are talking in exclusion to that interplay. Including TransitMatters, who've unfortunately been goaded by the Admin's monolithic framing games into all-or-nothing opposition of SSX instead of breaking it into its constituent parts for separate examination. Such as: separating the pros/cons of the traffic conflict solves in the base-most SSX track work package from the larded-on politics of station house monument-building and real estate tug-of-war...because if you're going to be fileting terminals to maximize service levels you're still going to want freer movements on/off the platforms instead of having spiraling Amtrak traffic bottle things up with constant cross-cutting movements. Likewise: breaking out the pros/cons of the storage yard land acquisition from the faulty SSX-vs.-NSRL framing...as securing the Widett Circle parcel would not only secure all southside terminal storage needs today but has the flex to be reapportioned for bus storage to consolidate the downtown garages should NSRL reduce the number of trainsets that need downtown storage. Some of these bits and pieces are necessary to have in any universe...but especially one where the be-all/end-all goal is securing 100-year service level growth. Unfortunately the pressure to debate on the state's monolithic framing ends up losing some details in the noise.

Everybody's got a lot of improvement to make in sharpening up their talking points. TM is taking first stab at that with their best "It's the frequencies, stupid!" step forward about Regional Rail operating practices being the only NSRL prerequisite that matters, and something that must proceed today on the system we have in order for the tunnel to have any value proposition worth pursuing. It would be nice if the Dukakis/Weld NSRL advocacy went lockstep with that, but they still seem to want to spin their wheels pushing run-thru for run-thru's sake when that's a born loser of an argument detached from any compelling vision about baseline frequencies. Clean it up some more from there and the frequencies! frequencies! frequencies! argument has a dead-on natural segue to the doubling of terminal district capacity, with all the run-thru advantages as an accessory to that lead-in.

I think I'm on board with your opinion, especially your final paragraph. Quick clarification, could you explain "upstairs and downstairs" a bit? I'm not sure exactly what you mean there, and my guesses don't quite add up in my head.

 

[JeffDowntown]

Re: North-South Rail Link

I think I'm on board with your opinion, especially your final paragraph. Quick clarification, could you explain "upstairs and downstairs" a bit? I'm not sure exactly what you mean there, and my guesses don't quite add up in my head.

Trains terminating at North Station (from the north) or South Station (from the south or west) would arrive at the surface platforms (upstairs).

Trains thru-running North or South Station via the NSRL would arrive at new deep underground platforms at both stations (downstairs).

 

[DominusNovus]

Re: North-South Rail Link

Trains terminating at North Station (from the north) or South Station (from the south or west) would arrive at the surface platforms (upstairs).

Trains thru-running North or South Station via the NSRL would arrive at new deep underground platforms at both stations (downstairs).

Thanks. That nakes sense, though it hadn’t occurred to me.

 

[F-Line to Dudley]

Re: North-South Rail Link

Thanks. That nakes sense, though it hadn’t occurred to me.

Yeah...play on words.

Tower A (northside) and Cove / Tower 1 (southside) are the system traffic limiters. They're on the surface serving the surface terminals, so for ID's sake they're the "upstairs" mash-up of lines.

NSRL will have its own matching equivalent of Tower A and Cove+Tower 1 interlockings underground where the portal tunnels join into a mainline. A "downstairs" mash-up, if you will.

Now, as a lateral trade (for the Seth Moultons who think surface terminals are icky-poo and should be decommissioned) you're not getting any better service simply trading the surface mash-up for the tunnel mash-up. It's treading water or worse because the speeds will be so slow in those steep, constrained lead tunnels that it'll nullify a good deal of the increases that come from run-thru ops. So to frame the NSRL argument in terms of TransitMatters Regional Rail's frequencies! frequencies! frequencies! -first ops goals, you have to be ready to go to battle for the tunnel on clear-cut service level advantages.

A lateral trade + run-thru doesn't make a frequency argument, because when all's said and done it's pretty much a push. But you've got a more compelling argument by saying "Going whole-hog Regional Rail will put us at the limits of the surface mash-ups...but digging the tunnel will DOUBLE total system capacity by being able to double-barrel service between 'upstairs' and 'downstairs' mash-ups one after the other."

^^Now you've got something--"DOUBLE the service"--that's a real "Wow!"-statement the public can concretely sink its teeth into and run with. And it's a natural segue from the thrust of the current Regional Rail advocacy. Go from talking up that killer service feature and then accentuate it by touting all the added advantages of run-thru service. But at the end of the day it's all a foundation built on service increases, and future-proofing Boston and Eastern New England for 100 years of service growth.

All of the disjointed advocacies (but especially the pols like Duke/Weld's outfit who can't seem to get their stories straight about what's the key selling point) need to sharpen up, clean up their talking points, and start pounding this simple drumbeat like it's mantra if we're going to educate a currently confused public about what this thing's core value proposition really is.

 

[fattony]

Re: North-South Rail Link

I'm not skilled in the art, so I'm trying to learn here. I think I understand the limitations of accessing the terminal through an interlocking and I would have figured that changing from a terminal to thru-run on essentially the same interlocking would increase capacity. The trains only have to traverse the interlocking once on the way in to the platform and a different interlocking on the way out. Are you saying that there SHOULD be a capacity increase from making it one-way, but that is offset by slower speeds on a grade? That is, the particulars of the NSRL are what make it a wash?

 

[F-Line to Dudley]

Re: North-South Rail Link

Yes. The tunnel grades are what they are; that's simply the geometry we were left to work with. Likewise, the busiest-of-all NEC/B&A direction still has to take a very sharp curve into those switches...only this time it'll be sharp curve WITH steep grade. So while you will get many of the advantages of run-thru, the unavoidable speed restrictions will roll back a fair chunk of those capacity gains. It's fundamentally an imperfect setup, but it's the only template we have to work with.


The perma-solve is fileting service through TWO wholly separate sets of interlockings service-balanced to keep any one set from getting overclogged. For example, Amtrak's largely going to stay surface-bound because that steep/curvy NEC lead tunnel is going to saturate its NSRL capacity soonest because of geometric speed restrictions that are worse than all the other lead tunnels. There isn't enough slack with those slow speeds to send all NEC/Worcester CR and intercity schedules down there. The system doesn't work if you don't continue sending loads of traffic through "upstairs" Cove interlocking. Mission-statement wise that means there has to be a narrative on how surface vs. tunnel slots will compare/contrast on schedules. It will be more than just Amtrak...so what Purple Line schedules are better-suited for which terminal?


Keep in mind as well that the underground stations are extremely deep and will take several minutes' longer escalator trips to get to the surface or hit a rapid transit transfer, so that will also inform what schedules are more appropriate to turn on the surface.

 

[Joel N. Weber II]

Re: North-South Rail Link

Would there be anything difficult about electrifying and quad tracking the Fairmount Line? Presumably if that could be done, everything south of Readville going into the NSRL could go via the Fairmount Line, and then perhaps additional trains from points south of Readville could serve Ruggles, Back Bay, and the South Station surface platforms. Apparently Amtrak did actually use the Fairmount Line at one point in the past when the Orange Line's current route along the NEC was being built, and Amtrak seems to love serving as few stations as possible in downtowns of major cities, so perhaps they'd be willing to skip the Back Bay stop.

Are there any PDFs of environmental studies that detail the tight curve issues anywhere?

 

[esmanga]

Re: North-South Rail Link

Is there a map of elevations available? Not just for NSRL but all the Boston tunnels.

 

[Arlington]

Re: North-South Rail Link

Is there a map of elevations available? Not just for NSRL but all the Boston tunnels.

Galore. I'd try a Google Image Search where site:archboston.org and then browse that.

 

[esmanga]

Re: North-South Rail Link

Galore. I'd try a Google Image Search where site:archboston.org and then browse that.

Thanks. I was more looking for 'depths' of tunnels. F-Line appears to have them all memorized (lol) and was looking for a visual.

 

[CSTH]

Re: North-South Rail Link

Is there a map of elevations available? Not just for NSRL but all the Boston tunnels.

http://www.northsouthraillink.org/alignment/

 

[F-Line to Dudley]

Re: North-South Rail Link

Would there be anything difficult about electrifying and quad tracking the Fairmount Line? Presumably if that could be done, everything south of Readville going into the NSRL could go via the Fairmount Line, and then perhaps additional trains from points south of Readville could serve Ruggles, Back Bay, and the South Station surface platforms. Apparently Amtrak did actually use the Fairmount Line at one point in the past when the Orange Line's current route along the NEC was being built, and Amtrak seems to love serving as few stations as possible in downtowns of major cities, so perhaps they'd be willing to skip the Back Bay stop.

Are there any PDFs of environmental studies that detail the tight curve issues anywhere?

Yes, when the SW Corridor was closed for reconstruction from 1979-87 all Amtrak, Providence/Stoughton, and Franklin trains used the Fairmount Line. There was no passenger service on the line prior to that, and today's Readville shuttle was a concession upon the SW Corridor's reopening to keep service on the line by popular demand instead of mothballing it all over again.

-------------------------

There is nothing difficult about electrifying Fairmount. It's already been proposed.

There is EVERYTHING difficult about quad-tracking it as north of River St. in Hyde Park it is very closely abutted most of the way by adjacent homes up atop the embankment. It's also curvier than the Ruggles-Readville portion of NEC and can't sustain the same high speeds Amtrak goes.

I'm not sure what you're trying to accomplish by overloading one bore of NSRL to underload another. It doesn't end up buying you any more slots to run straighter, any more than it would today on the surface. Worcester trains are still approaching the mash-up on that sharp, steep curve so the traffic merging inside the tunnel is still going to be slow and plodding. What it does do is make on-time service a more brittle proposition. You're now proposing to come in on the inferior-speed and inferior-capacity mainline, meaning that those ex-NEC schedules now have to be stripped to the bone on nearly all padding margin for error to make up for lost time on the mainline. Hit the portal with no cushion, and all it takes is one merging conflict to blow your schedule...on a schedule that's got to keep going on the northside.

It's important to understand the critical role that Back Bay plays in NEC traffic management. Back Bay is part-and-parcel a dispatcher component of Cove interlocking in the terminal district. By virtue of having that stop a stone's throw from the big mash-up, dispatch can schedule BBY departures and arrivals to keep an even and orderly churn through all those congested switches. A blown schedule doesn't need to gunk up traffic, because the pecking order for who's got priority can be adjusted within the time of a normal BBY dwell time. That's the main reason that NO trains--T or Amtrak--on the NEC/B&A ever skip BBY; if you had some scheduled to blow straight through the terminal district would no longer function.

Back Bay performs the same function with NSRL at setting the pace to/from the Washington St. tunnel portal and the underground mash-up. Despite the steep underground curve the NEC portal is going to be able to support inherently higher traffic levels than the Southampton portals for the Old Colony + Fairmount because it is still dispatched in-tandem with that BBY pacemaker. You don't have a terminal district stop by Southampton; it's all train yards. Those lines are run from Newmarket or JFK/Quincy/Braintree and are hitting their slots at the terminal mash-up while in-motion. That direction needs slightly wider train spacing at its merges to keep a safe margin for error, because it doesn't have a built-in pacemaker like BBY. That direction has achieved its proper margins by having somewhat lower intrinsic traffic levels than the NEC/B&A dating all the way back to when SS was originally built. It's by design.

-------------------------

Also, Joel...you seem to have missed the whole part about "Amtrak's largely going to stay surface-bound"? Except for any super-extended Concord or Portland NE Regionals...they're not going to be thru-routing via the tunnel. Every Acela, Regional, Inland, Lake Shore Ltd., etc. of theirs has to pit-stop between runs at Southampton to change crews, restock food service, empty toilets, etc. They always are doing a stub-and-reverse. And it's always going to be easier for them to do that at their HQ @ Southampton rather than a shared T yard on the Woburn town dump next to Anderson RTC. They're easily going to take up greater than a third of SS surface by their lonesome at projected 2040 service levels, so right there is the incentive for doubling the system capacity.

The only Amtrak route that's likely to use the tunnel every time is the Downeaster, simply because it's easier (if the national fleet has a few dual-mode locos to spare) to dump out at Southampton HQ for the same re-crew/restock chores rather than bogarting a remote parking spot in Somerville. But vacating North Station surface just means those DE slots get instantly gobbled up by more NHDOT-subsidized Purple Line trains from Concord and Dover, so there's no shortage of service increase mouths to feed.

 

[orulz]

Re: North-South Rail Link

The only Amtrak route that's likely to use the tunnel every time is the Downeaster, simply because it's easier (if the national fleet has a few dual-mode locos to spare) to dump out at Southampton HQ for the same re-crew/restock chores rather than bogarting a remote parking spot in Somerville. But vacating North Station surface just means those DE slots get instantly gobbled up by more NHDOT-subsidized Purple Line trains from Concord and Dover, so there's no shortage of service increase mouths to feed.

If I recall, TransitMatters was suggesting saving money by making the NSRL an EMU-only facility with grades even steeper than 3%. This is obviously a trade-off, but it would preclude through service on the Downeaster until the whole route up to Portland can be electrified.

An electrification project like this may seem like a heavy lift from the perspective of the US of A, but it would have already been done 30 years ago in continental Europe or Japan. I wonder if it's possible that the money saved via steeper NSRL grades could pay the full cost of electrifying the Downeaster. Certainly at European electrification costs it would be comparable.

 

[DominusNovus]

Re: North-South Rail Link

Has anyone tried asking Elon Musk and The Boring Company if they’d be interested in digging this? I say this only half-joking; I have to think there’s some room for a public-private partnership to get this tunnel dug.

 

[orulz]

Re: North-South Rail Link

I'm not sure what you're trying to accomplish by overloading one bore of NSRL to underload another. It doesn't end up buying you any more slots to run straighter, any more than it would today on the surface. Worcester trains are still approaching the mash-up on that sharp, steep curve so the traffic merging inside the tunnel is still going to be slow and plodding. What it does do is make on-time service a more brittle proposition. You're now proposing to come in on the inferior-speed and inferior-capacity mainline, meaning that those ex-NEC schedules now have to be stripped to the bone on nearly all padding margin for error to make up for lost time on the mainline. Hit the portal with no cushion, and all it takes is one merging conflict to blow your schedule...on a schedule that's got to keep going on the northside.

I think I see the point. It's not about overloading/underloading bores. It's about simplifying. Current plans would allow every train from every line to be able to access both surface terminals AND the NSRL.

But what about connecting NSRL *only* to Fairmount/Old Colony. Eliminate the interlockings entirely. Do the business of filtering trains to their final destinations at Readville rather than 100 yards south of the platforms at South Station. On a train bound for NSRL but need to get to Ruggles or Back Bay? Change at Readville, which basically becomes Boston's equivalent of Jamaica.

Trains from Providence, Franklin, and Stoughton could still access the tunnel via Farmount. If necessary, quad tracking wouldn't be easy and numerous bridges and stations would need to be rebuilt, but the right of way and many existing embankments seem like they are mostly wide enough. This would be a project roughly equivalent to Caltrain's modernization, only 7-ish miles long instead of 50-ish.

The Worcester line would lose their connection to NSRL, but then that could be traded for a cross-platform transfer at West Station/Allston to the Grand Junction line for a northern route.

I realize this is not the perfect, optimal, most flexible configuration. But there has to be a sober, well-reasoned conversation of the benefits gained versus the costs spent. In Tokyo, with which I am quite familiar, trains from the Yokosuka line can only travel through to the Sobu line. If you're at an express station on the Sobu line, you have your choice of running through to the Yokosuka or Chuo line, but there's no direct service to the Tokiado or Saikyo line. By requiring connections from everywhere to everywhere, you're forcing complexity and adding more failure modes. Complicated branching service patterns hinder frequency.

Just a thought.

 

[Arlington]

Re: North-South Rail Link

Also, Joel...you seem to have missed the whole part about "Amtrak's largely going to stay surface-bound"? Except for any super-extended Concord or Portland NE Regionals...they're not going to be thru-routing via the tunnel. Every Acela, Regional, Inland, Lake Shore Ltd., etc. of theirs has to pit-stop between runs at Southampton to change crews, restock food service, empty toilets, etc. They always are doing a stub-and-reverse. And it's always going to be easier for them to do that at their HQ @ Southampton rather than a shared T yard on the Woburn town dump next to Anderson RTC. They're easily going to take up greater than a third of SS surface by their lonesome at projected 2040 service levels, so right there is the incentive for doubling the system capacity.

The only Amtrak route that's likely to use the tunnel every time is the Downeaster, simply because it's easier (if the national fleet has a few dual-mode locos to spare) to dump out at Southampton HQ for the same re-crew/restock chores rather than bogarting a remote parking spot in Somerville. But vacating North Station surface just means those DE slots get instantly gobbled up by more NHDOT-subsidized Purple Line trains from Concord and Dover, so there's no shortage of service increase mouths to feed.

I thought it just as likely that the Acelas would run through to Woburn (for an Acela only yard and a great park-and-ride terminus a la RTE) whereas the loco-hauled NERs and LSL would terminate at SSX, and a loco-hauled Downeaster would offer Acela connections at Woburn but terminate at NSX

 

[boston85]

Re: North-South Rail Link

Has anyone tried asking Elon Musk and The Boring Company if they’d be interested in digging this? I say this only half-joking; I have to think there’s some room for a public-private partnership to get this tunnel dug.

Trains are too archaic for Musk to bother with. It's hyper loop or bust. And, I am only slightly joking. He skipped over the easy win with automated/electric port trucks and electric delivery trucks and went to an overly ambitious long haul semi product(which is withering on the vine).

 

[DominusNovus]

Re: North-South Rail Link

Trains are too archaic for Musk to bother with. It's hyper loop or bust. And, I am only slightly joking. He skipped over the easy win with automated/electric port trucks and electric delivery trucks and went to an overly ambitious long haul semi product(which is withering on the vine).

I agree, in general. But I have to think someone out there, regardless of whether it is Elon, could make some money off this project.

 

[F-Line to Dudley]

Re: North-South Rail Link

If I recall, TransitMatters was suggesting saving money by making the NSRL an EMU-only facility with grades even steeper than 3%. This is obviously a trade-off, but it would preclude through service on the Downeaster until the whole route up to Portland can be electrified.

An electrification project like this may seem like a heavy lift from the perspective of the US of A, but it would have already been done 30 years ago in continental Europe or Japan. I wonder if it's possible that the money saved via steeper NSRL grades could pay the full cost of electrifying the Downeaster. Certainly at European electrification costs it would be comparable.

The actual project engineering is pretty much cut-and-dried, and there aren't cost savings to be had by radically reimagining it.

1. SS Under or NS Under are slotted a set depth underground in the mainline tunnel, as per the diagram CSTH linked to. Nothing is changeable here because of the Big Dig above.
2. Portals have to fit where there's room, and because of surrounding infrastructure there's extremely limited play in where they can be located. The NEC's portal must be on the Washington St. block because west of there the Orange Line is crossing under and east of there ends up smack in the middle of all the switches for surface Cove interlocking. The OC/Fairmount portals have to split shallow-level on flanking sides of Amtrak Southampton shops, because immediately north of there are all the switches for surface Broad interlocking, plus the Commuter Rail and Red Line shop buildings. The northside Fitchburg and Lowell+Eastern+Western more or less mirror the shallow split at Southampton by coming up on flanking sides of Boston Engine Terminal...because same as Southampton slotting any further south runs smack into the maze of switches for surface Tower A interlocking.
3. If depth is locked in at X ft. below and the portals are more or less locked in Y ft. away...then the grades are likewise set at Z% because the other variables aren't ever going to change.

No, you're not going to end up saving money by trying to dig shorter but steeper...because you'll have no place to put the portals if you try to move them any closer to the stations.


Now, the physical engineering for the tunnel was not where the state's report had a total cost blowout. It was the fact that everything was predicated on ordering an entirely new, cleanroom fleet of dual-mode locos and half-assing the electrification so everyone had to power-switch a couple miles outside the tunnel. Massive capital outlays for equipment, and massive increase in operating costs to maintain each schedule with a baked-in power switch. As TM swung back in its reply, that makes absolutely zero sense the way electrification and EMU costs scale. And makes no sense when all it takes is electrifications of Fairmount + Worcester and an EMU fleet for those two + Providence + RIDOT intrastate to flip >60% of the southside's fleet requirements to EMU's.

So, yes, in all practicality it's going to be a majority-EMU system that runs through the tunnel...because we'll already have vast majority of the southside already running EMU's before the NSRL's ceremonial first shovel gets turned if they go ahead now/soon and adopt Regional Rail best practices. Some super-long runs where it'll take pricey second 25 kV substation installations to complete the electrification may end up going later in the queue (e.g. Fitchburg Line past Littleton, South Coast Rail past Taunton). Others may never make sense to completely electrify because service levels won't be high enough and the runs are too long to effectively pair-match (e.g. Middleboro-Hyannis, RIDOT Newport via Fall River, NHDOT Concord via Lowell/Nashua). And in the case of the outer Haverhill Line, electrification may be extraordinarily difficult and expensive because double-stack freight clearances will have maxed out every inch of clearance under the Lawrence street grid.

Chances are the diesel remainders left to mop up will be heavy surface users. And yes, that means some winners and losers like Haverhill riders being nearly always surface-bound because difficulty level makes them the very last of the I-495 lines to get wired-up. There still could be some bona fide utility in ordering a *small* dual-mode fleet for select instances where one of those un-wired remainders (esp. Haverhill) needs a tunnel slot every now and then. But think more like 10-15 units, not the 60-90 locos the state was quoting with its fuzzy math. And, yes, if this thing is going to have region-wide coattails Amtrak needs to be able to use it tpp with their own dual-modes or a Sprinter electric that engine-swaps to diesel at Anderson RTC. Those Portland and Concord Northeast Regionals are good analogues for the Virginia Regionals, and the Downeaster by this point will probably be stretching itself to Augusta and Bangor distinct from the Portland turns. The real heavy-duty AMTK traffic will still be surface-bound by their operational needs, but they do catch some bona fide coattails from the tunnel. It's mega for the NH and ME economies to be gaining one-seat rides to New York City multiple times per day.

Has anyone tried asking Elon Musk and The Boring Company if they’d be interested in digging this? I say this only half-joking; I have to think there’s some room for a public-private partnership to get this tunnel dug.

That's a half-joke too generous for Elon The Grifter. Have you seen how small his test tunnels are in those blurry YouTube videos? Assuming a blurry video even counts as "proof". You can't even fit a car through those...the very thing he said it would be able to do. Also...no doubt they've selected the absolute easiest-dig soils that are not at all geologically heterogeneous in contents, at perfectly level grades. Boring Company is just a hyperloop leftover for attempting a below-ground PRT cut. Only Musk is trying to scam any city that'll listen to him bloviate about using it for cars or something.

The diagram CSTH posted shows the different tunneling techniques that'll have to be used. This thing will be soft-scooped under I-93, go directly below existing RR tracks on the approaches, have to straddle out below a major body of water in Ft. Point Channel, and pass underneath multiple transportation tunnels and the Charles River.

That's 3 or 4 different tunneling techniques used to build it, because of 3 or 4 wholly different environments. It costs what it costs, and takes what it takes in terms of experience. Musk only knows how to do one thing...inflexibly.

I think I see the point. It's not about overloading/underloading bores. It's about simplifying. Current plans would allow every train from every line to be able to access both surface terminals AND the NSRL.

But what about connecting NSRL *only* to Fairmount/Old Colony. Eliminate the interlockings entirely. Do the business of filtering trains to their final destinations at Readville rather than 100 yards south of the platforms at South Station. On a train bound for NSRL but need to get to Ruggles or Back Bay? Change at Readville, which basically becomes Boston's equivalent of Jamaica.

Trains from Providence, Franklin, and Stoughton could still access the tunnel via Farmount. If necessary, quad tracking wouldn't be easy and numerous bridges and stations would need to be rebuilt, but the right of way and many existing embankments seem like they are mostly wide enough. This would be a project roughly equivalent to Caltrain's modernization, only 7-ish miles long instead of 50-ish.

The Worcester line would lose their connection to NSRL, but then that could be traded for a cross-platform transfer at West Station/Allston to the Grand Junction line for a northern route.

I realize this is not the perfect, optimal, most flexible configuration. But there has to be a sober, well-reasoned conversation of the benefits gained versus the costs spent. In Tokyo, with which I am quite familiar, trains from the Yokosuka line can only travel through to the Sobu line. If you're at an express station on the Sobu line, you have your choice of running through to the Yokosuka or Chuo line, but there's no direct service to the Tokiado or Saikyo line. By requiring connections from everywhere to everywhere, you're forcing complexity and adding more failure modes. Complicated branching service patterns hinder frequency.

Just a thought.

Read my reply to Joel for exactly why the Fairmount Line is no substitute for the NEC.

• Slower/curvier...must run with stripped-to-bone schedule margin-for-error to keep same times for Providence or Amtrak.
• No Back Bay Station "pacemaker". Merges are in-motion, not dispatched through the mash-up from the SS or BBY starting spot. There will be chance conflicts, and with no schedule padding that means any conflict--even the chance ones--makes you late. Late before you've even hit the northside portion of your run.
• The BBY "pacemaker" allows for more total throughput than in-motion merges. You have to keep somewhat looser train spacing with the Old Colony/Fairmount to handle in-motion passage through their Broad interlocking mash-up (Broad...like Cove+Tower 1...will also have its underground analogue). So far OC/Fairmount projects to be the wider-spaced traffic direction for all foreseeable future, even after all Franklin/Foxboro traffic gets routed via Fairmount to avoid NEC congestion. But if you start throwing Providence and AMTK traffic through there stripped of all cushion for the slower routing, the number of chance conflicts increases. And those have consequences.
• What is the point of run-thru if these schedules are going to be stripped so brittle that they end up bogging down the northside running late all the time? We aren't patting ourselves on the back here over pyrrhic victories simply getting inside the tunnel. There's another end to spit out of and more schedule to cover. Having to wheeze through the last-mile leg into the terminal district either means that schedule is NOT appropriate for a tunnel slot and should terminate on-surface...or, that you've got a lot of work to do improving the reliability into the terminal district. Intentionally re-routing to the poorer-performing line is a step backwards from where you need to be reliability-wise on a tunnel pairing.

RE: other points. . .

• No...again...Fairmount is NOT quaddable. South of River St. where it used to be a continuous swath of freight yards...yes, that has the width. Couple places that used to have freight sidings...maybe some ROW slack for a few feet at a time. But, please, look at the blocks north of River St. on Google and see how you are ever going to double the width of that thing without knocking down lots of houses. No force-fit is worth that swath of destruction.

• Why if building one lead tunnel would one ever choose to NOT build the one that carries more traffic in lieu of the one that carries less. We're getting way too wrapped up in the fact that the NEC has a curve on it at all. We don't have a train station out on a buoy in the middle of the Harbor, so of course there's going to be a curve. None of these lead tunnels are going to be fast trips down those steep grades in constrained spaces, so the degree of difference between the so-called "straight" one and the so-called "curvy" one isn't massive. However, the NEC side can handle a more orderly passage of traffic because...much like the surface...it has that Back Bay "pacemaker" working for it. And that is massive. If you have to defer construction of any portals out of short funds...and both tunnels are equal 1 mi. length and equal quantities of concrete...then the OC/Fairmount tunnel one is hands-down the first cut. Demand: (NEC + B&A) > (OC + Fairmount)...by a humongous margin. I don't even know why that's in question.

• I recommend reading the Worcester-North Station study for the Grand Junction. You're seriously overestimating what capacity it has to give. Also...it may not be able to be electrified for commuter rail because the Memorial Drive overpass is too short for any bi-level equipment to pass safely under a 25 kV wire. As mentioned in other threads, it works way better as a light rail ROW that can share traffic signal phases at Main St. and Broadway. And you can rip that sucker right off the RR network to make it LRT/BRT without NSRL being a project prerequisite.

I thought it just as likely that the Acelas would run through to Woburn (for an Acela only yard and a great park-and-ride terminus a la RTE) whereas the loco-hauled NERs and LSL would terminate at SSX, and a loco-hauled Downeaster would offer Acela connections at Woburn but terminate at NSX

Their premier-tier service...terminating in Woburn out in the 'burbs??? I don't think so. The NEC FUTURE Commission doesn't mention anything about that, and all their reports duly footnote NSRL as a consequential traffic influencer their studies need to factor in.

Amtrak has an established presence at Southampton and up to another 300,000 sq. ft. to expand on the Frontage Rd. side of that parcel by relocating the employee parking lot, consolidating utility sheds, and excavating under the Fairmount Line embankment to hook an expanded yard into the Widett Circle loop track. They're not going to be splitting their presence if they don't have to, because keeping consolidated at Southampton is a cost control for some of their loss-leadery services like food service and baggage handling. Having to duplicate those functions and others at Woburn doesn't make any dollars or sense to them.

Also, Woburn may have a goodly amount of flat land for a layover...but the usable acreage is less impressive than it appears on Google. The hilly landfill caps (i.e. where the solar arrays are) can't be built on and are too steep for tracks. After the T has taken its share there's not going to be a huge amount of land left to split with Amtrak for any heavy-duty functions like all Acelas or NE Regionals running thru. If anything, Anderson is well set-up for an engine change from electric to diesel for a Portland or Concord NE Regional, or an Augusta/Bangor-bound Downeaster. Engine shed + service track with some onsite employees would suit them fine. But that's about it, and probably all they'd ever truly want out there.