GLX Impact on NH Route (Lowell Line)

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Re: GLX Impact on NH Route (Lowell Line)

Postby RenegadeMonster » Tue Oct 24, 2017 7:12 pm

I'm pretty sure they have managed 3 trains in 10 minutes At Salem when they were running off schedule due to a train being behind schedule. Two in one direction and the other in the opposing direction.
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Re: GLX Impact on NH Route (Lowell Line)

Postby F-line to Dudley via Park » Tue Oct 24, 2017 8:21 pm

BostonUrbEx wrote:I never suggested scrubbing GLX today. I'd say it should have been planned differently from the start, decades ago!


This is even more disingenuous! The "Beyond Lechmere Northwest Corridor Study Major Investment Analysis" from 2005 quite literally scored LRT, BRT, and commuter rail modes against each other and crunched all the demand numbers in the appendices showing point-blank where native Somerville ridership does and doesn't get dispersed downtown. The existence of magical 1998 alternate-universe NSRL ribbon-cutting does not flip the travel patterns on their head from the Central Subway to the Waterfront/South Station. The CTPS data reaffirmed 100 years of established travel patterns on this corridor: they pour into Lechmere and go to Haymarket, GC, Park, and the stations along Boylston St. in huge numbers in addition to North Station. They even re-crunched the numbers based on presence of the Urban Ring changing the spread of linked trips around Cambridge, and it simply reaffirmed the original conclusion.

Go on the document archives on greenlineextension.eot.state.ma.us, start with Appendix F and work through the study docs from there, and prove the math is dead-wrong, upside-down, or backwards through your own number-crunching analysis. This project rests on burden of proof calculations so many levels deep that it can't be upended by throwing a couple stones from the sidelines and arguing-via-obscurity that a bunch of old-school planning dinosaurs weren't being "forward thinking" because reasons.

SHOW where the modal choice not made is superior for where people need to go, and what not-at-all-voodoo mechanism turns 100-year demand patterns onto an entirely different corridor.

I'm not convinced. Salem has inbounds scheduled within 10 minutes of each other while utilizing diesel locomotive-hauled sets, a track/signal system that could be improved, and all on a single track pinch point. There is a point in the day where Salem sees trains every ~8 minutes (including both directions, but remember this is single track, so with opposing moves that's even more impressive). Not to mention, the discussion at hand involved quad-track.


And this factoid artfully tapdances around the key-most point I made. Mainline rail can absolutely pack headways close. It cannot, because of the more heterogeneous traffic profile (that gets MUCH more diverse post-NSRL when scaled to the Lowell Line), guarantee that every Urban Rail local throughout a given shift sticks as close to the advertised headway as a closed metro/tram system can. A longer-distance train is going to get more schedule padding on a slot, and will clip and shift the margins of that MU schedule by a couple minutes a couple times an hour. That puts schedule consistency outside the margin of error a metro/tram system would be able to hold.

Quad-tracks? What does that matter when you're still mashing into 2 NH Main tracks for the NSRL portal...then merging 2 NH Main, 2 Fitchburg, and 2 Eastern/Western tracks--each with their own hetereogeneous short and long-distance scheduling--into 4 tracks of the main bore. With all the associated interlockings, and the upstairs/downstairs splits from the retained surface terminals. The local tracks on the NH Main aren't hermetically sealed from the effects of slotting longer-haul traffic when they all engage each other in the Terminal District. They get their headway variability fileted in the Terminal District by what's got priority at any given moment. And this is where absolute frequencies will never end up meeting what the Green Line could provide, as well as being able to meet the shift-long consistency of the headways. Are pretty good frequencies achievable that way? Yes. Are those frequencies good enough to satisfy Somerville demand growth like the Green Line can? No...not even close, say the studied-to-death demand numbers. The two modes aren't interchangeable for that task because the NSRL is predicated on continued (or even expanded) existence of a hugely complicated union station terminal district in the CBD, while the Green Line for all its warts does not.

This is why first-world cities still segment their metro/tram and mainline rail modes by purpose even when coverage overlap on a corridor is semi-intentional. And why magic "Uni-mode" hasn't wiped the slate clean like all the BRT astroturfers and prophets of the DMU gospel said it would. Because well-planned transit systems don't pick the inferior tool for the stated job for proof-of-concept bragging rights. The NSRL can't move enough Somervillians often enough to where the highest percentages of them need to go to be in any way a drop-in replacement for GLX. Even in magic alternate universes where we started Link construction in 1995.

However, if you want to calculate what Jetsons-tech dispatching precision can do to close the gap at a technical level, go right ahead. But do not do that with one hand while feigning ignorance with the other on what the demand numbers are. Those have to be substantiated too. A narrower performance gap between RR and LRT modes doesn't mean RR mode "wins" when more people on this corridor still, after 100 years, need to get down the Central Subway corridor than need to get down the NSRL corridor and swapping the two means demand goes unmet. It means making more half-arsed compromises that don't address the very question being asked. The end result is little different than the intensity of belief in BRT-for-BRT's sake that dictated to Roxbury: "Your pleas for a one-seat from Dudley to the nerve center of the Big Four transfers are baseless because instead we're giving you the one-seat to the Seaport and Airport you never asked for, and that's better than nothing."
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Re: GLX Impact on NH Route (Lowell Line)

Postby F-line to Dudley via Park » Tue Oct 24, 2017 9:11 pm

RenegadeMonster wrote:I'm pretty sure they have managed 3 trains in 10 minutes At Salem when they were running off schedule due to a train being behind schedule. Two in one direction and the other in the opposing direction.


OK. Now take that one isolated example, even it up so inbound frequencies direct-match outbound frequencies around the tunnel and that single-track platform, and hold to that headway for every trip for 3 straight hours of each peak period 5 days a week. Hold that frequency for inside-128 locals through every slot that has to take a Newburyport/Rockport terminating in the outskirts of Essex County, every skip-stop trip, every train meet with the Western Route at Reading Jct., and traffic priority at Tower 1 and FX interlockings.

Tally it up. How many trips will have to miss their headway by >2 minutes because of priority and padding granted to longer-haul traffic that has to share those rails? How many of those trips to/from I-495 land will skip-stop the lesser-ridership rapid transit -spaced stations for the sake of their schedules and interrupt a headway for the Indigo-level service at those skipped stops?...20, 30 times per day?

Now take the midday shift and do the same at a consistent midday both-direction headways for the whole 6.5 hour duration of midday when CSX and PAR freights have to get their slots through the Terminal District and on the Eastern Main during that shift amid a lighter sprinkling of Rockburyports and Tower 1/FX/Reading meets.


We're not looking for proof-of-concept single instances of train packing. Those headways need to be sustained through the whole shift without wandering up or down by several minutes for each adjustment where some other route's schedule gets its turn at priority. Otherwise, it's not a drop-in substitute for how the subway system runs its headways by shift and isn't going to serve the same demand profile.

And while that's very impressive train packing for CR, keep in mind that GLX will be running to College Ave. at D Line headways: 6 mins. peak, 8 mins. weekday off-peak, 11 mins. late night. You're not fully substituting for GLX demand served if 10 minutes is the headway floor you can consistently achieve throughout a whole shift without variance, and anything less than that is subject to gaps and spikes of 2-4 min. variance because of how priority has to be shared in the Terminal District and with other mainline schedules.


Pretty good headways that fall well short of a rapid transit shift's throughput ≠ a rapid transit substitute. This is inherently hard to do on a mixed system, let alone on legacy mixed system that's attempting a radical retrofit shivving the NSRL into tight confines and complex existing surface interlockings. It is not nearly as hard to do on a linear extension of the Green Line off the under-capacity Lechmere end...determined by multiple official studies to be far and away the most straightforward tool for the job being asked. Beware losing sight of that because of target fixation on the proof-of-concept or compulsion to equate "couldas" found attached to needles in a haystack with "obvious and overwhelming evidence of fit" crunched through 20 years of official study. If it doesn't serve all the main project goals of GLX for moving people to/from Somerville and the places they MOST need to go downtown, it's not a drop-in substitute for GLX.
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Re: GLX Impact on NH Route (Lowell Line)

Postby BandA » Tue Oct 24, 2017 11:28 pm

Lotta stuff. A DMU and a Green-Line Type-9 cost about the same and are both kinda custom animals. A DMU is less energy-efficient, but fuel cost is a fraction of the labor, maintenance and capital costs. DMU wouldn't require catenary. A GLX station and an Indigo station with the same amenities should cost exactly the same. According to Cummins literature https://www.cdc.gov/niosh/mining/userfiles/workshops/dieselaerosols2012/nioshmvs2012tier4technologyreview.pdf, Tier-IV final diesel emissions are 99% less than unregulated old engines and 90% less than Tier-III, which is the best the MBTA owns. CNG powered engines would be even cleaner and practical on all north-side lines (i.e. not under the Prudential Center). So there are other options to emissions reduction than trolleys. And I'll worry about CO2 when China gets serious about reducing their output below say 2000 levels. You could engineer a DMU or push-pull train to have similar acceleration to a trolley -- just boost the h.p. & add some batteries for impulse power. Or use an EMU designed to run on battery power when it goes under a bridge.

I asked the T a couple of years ago why the GLX wasn't attached to the Orange Line instead of Green. Would have been simpler & the rolling stock is cheaper, higher capacity & lower dwell. They responded that the GLX was already planned & permitted so it was too late to change.

I've gotta believe that managing a four-track rail lines is easier and more flexible than managing two incompatible two-track rail lines. So we are left with FRA having more bureaucratic regulations for blocks as the deciding factor? Does heavier railroad equipment have longer stopping distance than trolleys?
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Re: GLX Impact on NH Route (Lowell Line)

Postby Bramdeisroberts » Wed Oct 25, 2017 5:37 am

BandA wrote:Does heavier railroad equipment have longer stopping distance than trolleys?


Uhh, yes. Absolutely. And it's not even close.

Other than that, you're right about the GLX being better as the OLX. For the price of the stations that the Time is already building, there's no reason why it SHOULDN'T be serving 6-car heavy rail trainsets that as you said eviscerate an LRV when it comes to speed, capacity, and dwell times. Furthermore, 3rd rail electrification is cheaper to install than catenary, and aligning an OL spur from between Community College and Sullivan to the NH route via the yards would be easier than relocating Lechmere, etc, with the added benefit of not setting off the NIMBYs in Brickbottom.

The only reason I can think of for why it ended up being green vs orange was again the NIMBY factor. The Orange Line has always had a certain, uh, reputation given the sorts of rougher neighborhoods that its southern end historically traveled through. If you're selling a rapid transit extension to a somewhat skeptical community that is already going to completely transform neighborhoods when it adds $100k+ of value to each and every home within a couple miles of it on the day it opens, it helps when you can sell it on connecting those communities to happy, friendly things like The Public Garden, the MFA, Back Bay, Newton, and Coolidge Corner, rather than Ruggles, Roxbury Crossing, and Jackson Square.
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Re: GLX Impact on NH Route (Lowell Line)

Postby deathtopumpkins » Wed Oct 25, 2017 8:34 am

BandA wrote:I asked the T a couple of years ago why the GLX wasn't attached to the Orange Line instead of Green. Would have been simpler & the rolling stock is cheaper, higher capacity & lower dwell. They responded that the GLX was already planned & permitted so it was too late to change.


Meanwhile I've asked that same question and been told that it would dilute Oak Grove frequencies too much.

The Green Line was a better choice because it's extending a line from a terminus, rather than creating a new branch off another line that is already over capacity. Maintaining current Oak Grove headways would require running trains to Forest Hills every 3 minutes during peak. Potentially overkill on the south end, and high potential for dwell time downtown destroying schedule adherence, plus leaves little to no room for future growth on the existing Orange Line.

GLX is also an excuse to get out of the tiny cramped Lechmere yard in favor of a modern facility with room for expansion. The Orange Line already has a nice big yard at Wellington that would inconveniently be located on only one branch of an OLX. This means that a Somerville OLX would need at the very least a small yard at the end to store trainsets for start and end of service.

An Orange Line branch also wouldn't be able to serve Union Square, unless you add a second branch, which then means 3 separate branches would all be feeding into the southern half of the Orange Line.

As much as I would prefer Orange Line instead of Green (I live within walking distance of a GLX station but work off the Orange Line; plus I hate riding the Green Line), logically Green just makes more sense.
Last edited by deathtopumpkins on Wed Oct 25, 2017 8:41 am, edited 2 times in total.
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Re: GLX Impact on NH Route (Lowell Line)

Postby deathtopumpkins » Wed Oct 25, 2017 8:38 am

Bramdeisroberts wrote:Other than that, you're right about the GLX being better as the OLX. For the price of the stations that the Time is already building, there's no reason why it SHOULDN'T be serving 6-car heavy rail trainsets that as you said eviscerate an LRV when it comes to speed, capacity, and dwell times. Furthermore, 3rd rail electrification is cheaper to install than catenary, and aligning an OL spur from between Community College and Sullivan to the NH route via the yards would be easier than relocating Lechmere, etc, with the added benefit of not setting off the NIMBYs in Brickbottom.

The only reason I can think of for why it ended up being green vs orange was again the NIMBY factor. The Orange Line has always had a certain, uh, reputation given the sorts of rougher neighborhoods that its southern end historically traveled through. If you're selling a rapid transit extension to a somewhat skeptical community that is already going to completely transform neighborhoods when it adds $100k+ of value to each and every home within a couple miles of it on the day it opens, it helps when you can sell it on connecting those communities to happy, friendly things like The Public Garden, the MFA, Back Bay, Newton, and Coolidge Corner, rather than Ruggles, Roxbury Crossing, and Jackson Square.


Somerville has recovered from just as bad of a reputation as the other end of the Orange Line. That is seriously not a concern.

Somerville is NOT a transit skeptical community.

How would an orange line branch be less disruptive to Brickbottom than GLX? Are you suggesting routing it via the New Washington St/Cobble Hill area instead of south of BET?
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Re: GLX Impact on NH Route (Lowell Line)

Postby BandA » Wed Oct 25, 2017 12:09 pm

Actually, you could route it through Science Park, if a crossover can be built at North Station or Haymarket. You'd have to study the layouts.

This is probably moot, something they can do in 20 years when they replace the Type 9s or have a shortage of trolley equipment.

Isn't the Green Line Central Subway just as overcrowded as the Orange Line?
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Re: GLX Impact on NH Route (Lowell Line)

Postby deathtopumpkins » Wed Oct 25, 2017 3:24 pm

BandA wrote:Isn't the Green Line Central Subway just as overcrowded as the Orange Line?


Yes, but in a way that the GLX complements. The existing Green Line mainly brings passengers in to downtown from the west, the GLX will mainly bring passengers in to downtown from the north (RR east?). Basically instead of turning around downtown and running mostly empty back west, Green Line trolleys will instead head up to Somerville to pick up more passengers. This doesn't significantly increase the load on the Central Subway, and in fact might actually ease the load somewhat, by reducing dwell time eaten up by terminating trains downtown (as I understand it, B trains will still terminate at Park or GC, but D trains will run to Medford). The fewer trains that have to dump all their passengers and turn around, the more trains you can squeeze through.
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Re: GLX Impact on NH Route (Lowell Line)

Postby csor2010 » Wed Oct 25, 2017 5:07 pm

BandA wrote:Actually, you could route it through Science Park, if a crossover can be built at North Station or Haymarket. You'd have to study the layouts.

This is probably moot, something they can do in 20 years when they replace the Type 9s or have a shortage of trolley equipment.

Isn't the Green Line Central Subway just as overcrowded as the Orange Line?


Malden, North Station and Wellington are the #3, #4, and #7 highest ridership stations on the Orange Line and all have over 10K weekday boardings per the 2014 Blue Book. Branching service south of these locations (such as between North Station and Haymarket as you suggest) results in degradation of service to these stations through longer headways. For example, if the minimum OL headway through the Washington Street tunnel/Southwest Corridor is 5 minutes (estimating here, I don't have the actual # handy), then the minimum headway that could serve the Oak Grove branch is 10 minutes if the branch split is 50/50. Given these constraints, the only way to get a lower headway for Oak Grove is to make weight the split in favor of Oak Grove service, which in turn lengthens headways in the GLX corridor.

A heavy rail option for GLX suffers from the same capital costs of having to physically separate it from the Lowell Line and higher capital costs for stations (longer, high-level platforms), plus the cost of connecting the GLX alignment to the existing Orange Line. It's not necessarily easier or cheaper than GLX, and it inconveniences the entire north end of the existing Orange Line.
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Re: GLX Impact on NH Route (Lowell Line)

Postby John_Perkowski » Wed Oct 25, 2017 8:49 pm

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Re: GLX Impact on NH Route (Lowell Line)

Postby Diverging Route » Sat Oct 28, 2017 7:49 am

I started this thread exactly three years ago to talk about the inter-relationship between the GLX and NH Route ROW, not the GLX itself.


GLX Impact on NH Route (Lowell Line)

Postby Diverging Route » Mon Oct 27, 2014 7:12 am
This weekend the first visible impact of the Green Line Extension occurred on the NH Route (Lowell Line). So I thought I'd start a new thread to document progress and changes - which will be numerous over the next five+ years.


Thanks to the admin for the reminder. As one who rides the NH Route daily, it's going to be interesting to document here.
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Re: GLX Impact on NH Route (Lowell Line)

Postby ceo » Sat Oct 28, 2017 10:19 am

There's another NIMBY factor with GLX-as-OLX, and that's that the old Orange Line cars are horribly, unbelievably loud, as in louder than a commuter rail train despite being electric. Presumably the new ones will be quieter though.
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Re: GLX Impact on NH Route (Lowell Line)

Postby Arlington » Fri Nov 03, 2017 2:24 pm

OK everybody! We're back to the exact topic of this thread: the GLX's construction work's physical and operational impact on the Lowell Line, with news about the next two weekends' worth of work from MassDOT.

As on recent weekends, the operational impact on the Lowell Line will be bustituted all weekend while crews swarm over the right of way in the area around Tufts U/College Ave. The physical impact is that by Monday the cut-over of the Lowell Line the new interlocking will be complete:
Nighttime Construction Advisory
GLX Early Work Continues Along the Lowell Commuter Rail Line

Work continues along the railroad [Lowell Line] right-of-way in the vicinity of the Colby St and Burget Avenue neighborhoods in Medford.
On Friday, November 10th, work crews will enter the right-of-way adjacent to College Avenue and will continue working through the start of service Monday morning, November 13th. The purpose of this work is to complete the cut-over of track along the retaining wall north of the College Avenue Bridge. Construction activities will require the use of heavy equipment such as front-end loaders, back hoes, dump trucks, generators, air compressors, and construction lighting.

The GLX Team apologizes for any inconvenience this work may cause, and has instructed work crews to minimize impacts to the community. Similar work hours and activities are anticipated for the weekend beginning Friday, November 17th through Monday morning November 20th.
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Re: GLX Impact on NH Route (Lowell Line)

Postby Trinnau » Sat Nov 04, 2017 7:22 am

Arlington wrote:OK everybody! We're back to the exact topic of this thread: the GLX's construction work's physical and operational impact on the Lowell Line, with news about the next two weekends' worth of work from MassDOT.

As on recent weekends, the operational impact on the Lowell Line will be bustituted all weekend while crews swarm over the right of way in the area around Tufts U/College Ave. The physical impact is that by Monday the cut-over of the Lowell Line the new interlocking will be complete:


Not exactly true. If you read the statement, there are two weekends planned. The MBTA has not released any information regarding busing next weekend at this point nor does this release indicate anything (although admittedly it looks like a neighborhood noise advisory). Based on your picture on the previous page of the thread and the fact the release talks about two consecutive weekends, my guess is that they are throwing the mainline track to line up to the new crossovers, one track each weekend. This would allow service to continue on the track not being worked.

Typically, signal work follows track work. So my guess is the signal work will be done sometime after Thanksgiving to actually put Tufts in service.
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