Crazy Transit Pitches

[F-Line to Dudley]

...and here's the quick-and-dirty MS Paint drawing of what I described. Big, so enlarge it.

• Dashed lines are tunnel segments, solid lines are surface segments.
• Line thickness = 3 pixels per track (i.e. 4-track Tremont tunnel > 3-track NEC > 2-track all else).
• Dark green is existing Green Line, light green is new construction. Orange is Orange, purple is CR. NOTE: Purple is hard to see where new Green tunnel underpins Worcester Line, but it's there.
• Yellow boxes are station platforms.
• Points of interest are lettered. See legend below.
• Pike outline + ramps filled in with paint bucket under Pru to highlight. NOTE: This screencap doesn't show the Pike-to-Huntington WB ramp very well; it's right next to Prudential Station behind the letter "R".
• All of the South Station and Washington St. branch infrastructure out-of-view is identical to stuff previously covered on the Reimagining Green thread. Reference any of the MS Paint renders there.

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

Legend:

A. Existing 4-track Tremont tunnel w/flyovers, giving way to new 4-track tunnel extension to corner of Tremont/Marginal.

B. Tufts Station. 2 island platforms. Track layout: BBY outbound--BBY inbound; SS/Washington outbound--SS/Washington inbound. Down-and-over ped walkway to Orange Line fare lobby (out-of-view) not shown. Daylighted headhouse directly above in park.

C + D + E. "Tremont Jct.":

C. SS/Washington tracks diverge east.
D. BBY tracks diverge west.
E. Wye track connects the two for thru-routing.
​

If building any one leg of this network first in isolation, make sure Tufts + the 4-track tunnel extension + the hollowed-out space for the junction are pre-provisioned. Do this even if the other diverging track berths and wye area are left vacant for 20 years until the next funding installment.

F. SS/Washington tunnel duck-under of Orange Line tunnel.

G. Washington Branch at-grade split. (Herald St. portal not shown; see GL Reconfig thread for details.)

H. Orange Line portal (existing).

I. New tunnel to BBY. Under Marginal St. to Columbus behind Pike retaining wall (same as the SS tunnel east on Marginal). Cross diagonal under Pike (same as the Washington portal tunnel). Then slip under Worcester tracks into BBY Station.

Worcester Line + BBY Worcester platform must be temp shut down for duration of construction, service re-routed to North Station. Augment inside 128 with buses, expanded D Line frequencies, Yawkey shuttles best as possible during shutdown and ration limited Grand Junction/North Station capacity for Worcester/MetroWest thru trains.

J + K + L + M. Back Bay Station platforms. . .

J. Worcester Line (existing). Closed and disrupted during GL tunnel construction, put back together after. Green Line level built as shallow box tunnel directly under Worcester platforms, with tunnel roof forming new trackbed/floor of Worcester level.

K. Green Line (new). Shallow-level below Worcester tracks. Accessible from Orange platforms inside fare control by going down-and-over from Orange platform (Orange is on other side of wall from Worcester, Green directly under Worcester).

L. Orange Line (existing). No modification except for grafting down-and-over corridors onto egresses for Green Line level.

M. NEC (existing). Stet.
​

N. GL tunnel under Worcester Line. Shallow box tunnel, roof is Worcester trackbed. Slotted between air rights pegs because GL tunnel narrower than Worcester trackbed. Maximum possible structural impacts would involve side reinforcements along tunnel roof (arched roof?) closest to existing air rights pegs, but otherwise stays entirely within-footprint and shouldn't be any concern for fatal blockers.

O. Existing Central Subway, Copley Station, Copley Jct. (stet)

P. Turn off Worcester Line @ Huntington Ave., go down Huntington. Structural underpinning of side wall required when turning off Worcester footprint. Pike ramp to Huntington *should* be far enough upstairs to have no structural impacts, since existing Huntington tunnel passes below in same spot. (Needs verification, but at worst possible case ramp could be shut for 1-2 weeks while shivving in 1 support beam underneath.)

Q. Merge into old Huntington tunnel at-grade, roughly at point where it straightens out before the Prudential platform. Retain Copley Jct. tunnel for emergencies and alt routings.

R. Existing Prudential platform (stet).
​

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

NO MONEYBACK GUARANTEE: This is NOT studied anywhere near as well as the Marginal St.-east routing is, where the slip-under of the Orange Line was studied in the 70's for Washington St. LRT replacement. So no guarantees that the BBY connector won't take on cost bloat between Clarendon and the old tunnel interface @ Prudential for additional side-wall reinforcement of the air rights pegs. It should be completely structurally feasible because of the subway tunnel's narrower footprint than the air rights pegs straddling the wider Worcester ROW and lack of any structures or utilities underneath the Worcester trackbed. Very low odds of there being any fatal engineering blockers because this follows the golden rule of staying within boundaries of cleanroomed urban renewal transit infrastructure. It's the potential cost bloaters from engineering mitigation that are complete unknowns until a full DEIR gets done.

You can definitely build it...but it's impossible to guess today for how much $$$.

 

[Shepard]

Thanks, picture is very helpful. Of all the fantasies on Downbursts map - most of which are rather reasonable pitches - this of all of them seems to be the most capital intensive. I can't decide whether it's more or less feasible than BLX Kenmore. The whole integrated GL network as visualized here is probably more important than BLX Kenmore in the scheme of things. .

 

[Uncivil_Engineer]

FWIW, and I might be splitting hairs here, the Worcester Line does not remain straight west of Back Bay - it does a small dodge to the south around the Pike ramp, best shown in this 1971 aerial. This also shows the Worcester Line entirely uncovered east of Huntington; toggling to later years will show the air rights filling in. As far as I know, the bridge structure over the Worcester Line is still entombed within Copley Place, though the ramp to Dartmouth Street was removed and the one to EB Huntington re-aligned to merge with Stuart Street when this section was covered up.

 

[F-Line to Dudley]

Thanks, picture is very helpful. Of all the fantasies on Downbursts map - most of which are rather reasonable pitches - this of all of them seems to be the most capital intensive. I can't decide whether it's more or less feasible than BLX Kenmore. The whole integrated GL network as visualized here is probably more important than BLX Kenmore in the scheme of things. .

Important thing to remember about BLX Kenmore is that it's completely conditional on a Storrow Drive teardown. It doesn't exist at all unless. . .

1) . . .there is overwhelming popular mandate to get rid of the parkway between Kenmore and Charles Circle (or bust down to two-lane undivided park access road).

2) . . .the popular mandate includes a binding transit trade-in commitment to move equal number of bodies.


Without those two stipulations joined at the hip, it doesn't exist. You simply can't practically build it as a normal 20 ft. depth cut-and-cover subway under an intact Storrow EB and waterproof it against the Charles Basin flood zone in a sea level rise era. That can only be done at anything resembling practical difficulty level and expense if you're going shallow box tunnel that meets (if doesn't necessarily breach) the surface, such that the Charles-facing side wall acts as its own flood barrier and the roof fused to a re-poured Back St. retaining wall acts as a de facto spillway deflecting runoff back into the Esplanade soil. The transit structure is the passive flood barrier that the Back Bay side of Charles Basin currently lacks...but it can only act as a flood barrier if the Storrow EB roadpack is vacated. Such a build follows the golden rule from the Green BBY connector that single-point flood mitigation is way easier than linear flood mitigation, because the only places here you'd have to guard against 'drain effect' vulnerabilities with active flood protection like pump rooms are the final descent under the Muddy River and into Kenmore. Single-point vs. linear is the difference between flood-proofing costing a 'normal' share of the budget, or costing more than the transit itself.


So consider the build priority completely "other" because Storrow trade-in is the sole impetus. It can either go on-the-board as a high priority right away if the populace is convinced that Storrow must go and a shotgun transit commitment is the most equitable way to make it go. Or it doesn't exist at all on anyone's planning bucket list, because it can't exist without the Storrow teardown dependency.

If you're stepping things out, Green Line reconfig is the only one you can peg today on a real priority list. The purely conditional nature of BLX-Kenmore means it's strictly a bang-bang job that appears for extracurricular reasons. It's a good transit project--the load-bearing relief for the Central Subway is enormous and directly aids all that GL reconfig, and it's unusually inexpensive per tunneling foot--but it's still strictly conditional and only happens as result of one very specific non-transit decision.

 

[oyhimylm]

I'm putting this here because what I'm proposing would require a ton of deep tunneling.

Despite the relatively easy loop connection offered by the Grand Junction, the routing feels excessively close to the Downtown Core. It also lacks an ideal connection to the Red Line.

To me, two other regularly discussed routings, Green to Harvard via Allston and the Chelsea/Airport portion of the Urban Ring, are on radial trajectories that seem to be more appropriately distanced from the Core. The obvious suggestion of this is to connect those two segments with a connector at a similar distance from Downtown.

My Google Map of this connector

(Several stations have notes)

It would go from Harvard to Union, then towards Everett either via Gilman/Wellington or Washington/Sullivan. From there, it's a straight shot down the Eastern Route to Chelsea.

Unfortunately, the most or all of the Cambridge/Somerville portion would be deep tunneled.

The primary benefits would be: [1] The addition of a third Somerville -> Harvard transit link, and a significant improvement over the current southern link (the 86). [2] Rail access for Everett and Chelsea. [3] Dramatically better access between Orange-North and Cambridge/Somerville.

In addition, I would argue that the Gilman/Wellington routing would be better than Washington/Sullivan. Gilman has a much better catchment and dense development possibilities than Washington, and while Sullivan is a massive bus hub, an Everett station and the ability to move routes to make Wellington a bigger hub significantly blunt that advantage.

 

[F-Line to Dudley]

BU Central to Harvard is pretty much exactly what's proposed as an Urban Ring spur in all the official Phase II concepts, so that isn't far-fetched at all:

Take a light rail Ring where you assume that the Phase III cross-Brookline tunnel is unbuildable and that a Comm Ave. subway extension from Kenmore to BU Bridge is necessary for giving the Grand Junction a hook-in. That's pretty much what you've got here, except it's a Harvard AND Grand Junction split not an either/or. You'd have a flying junction past BU Central station separating the B from the Ring before they both ascend to the surface, and the subway portal for the Ring would pop out on the grassy hillside next to BU Bridge right by the Storrow rail bridge.

Easy at-grade junction on this hillside:

• Grand Junction ring traffic bangs a right and heads over the bridges.
• Harvard Branch traffic bangs a left onto the old Grand Junction incline under the Pike viaduct to Beacon Park.
• Wye track allows for thru running from the Grand Junction to Harvard, skipping BU Central and the Comm Ave. subway.

The trek across Allston from West to N. Harvard can be completely above-ground and grade-separated so long as Harvard's grand redev of Beacon Park preserves an unbroken transit reservation on the plazas in front of the new buildings (Harvard's own Allston Master Plan says the transit reservation is planned and sacrosanct, but there's no legal obligation keeping Harvard from changing it's mind). If so, the only thing the build entails from BU Bridge portal to N. Harvard is a trajectory that crosses the street grid at 90-degree angles to enable minimalist overpasses. e.g. Tweak the map to conform to property lines, recycle the freight spur underpass of Cambridge St. by the tolls if any of that grade separation gets preserved as post- Pike realignment residue, curve around the Ohiri Field perimeter instead of splitting the middle, etc.


The only tunneling then required is the big-deal Charles crossing. To do that you've got to go about 2 blocks further west than where your map currently draws, because the structural insertion points into Harvard Station all cling to a Brattle Sq. alignment and not JFK St. Here's how it would go:

• Start at "Harvard Biz." station @ Ohiri Field. Align the track to curve along the south border of the field and cross N. Harvard on an overpass into the Stadium parking lot. May want your Harvard Biz. above-ground station to be right here on the south end of Ohiri all along to tee up that eventual tunnel trajectory, or to relocate it across the street in the Stadium parking lot when time comes to add the tunnel.
• Curve out of the parking lot to behind the Stadium, splitting between the Stadium and O'Donnell Field. Start inclining down and hit a portal somewhere behind the 1st-base side bullpens @ O'Donnell.
• Start descending into a deep bore tunnel.
• Trace a straight line across the river from the Stadium side path to the leafy ped plaza splitting the JFK School complex. This is the trajectory you must hit for reaching Harvard Station. Keep it straight except for a slight S-curve shimmy around building foundations on Soldiers Field Rd. (you're deep enough that passing under building cornerstones won't cause problems, so don't swerve too severely).
• Incline up to cut-and-cover depth by the JFK School plaza out to the corner of Bennett & Eliot St.'s.

Final hook-up to Harvard Station is then:

1. The bus tunnel...swerve cut-and-cover from plaza to Bennett Alley, merge into bus tunnel mixed-traffic. Some street-running improvements around Cambridge Common for more efficient bus/trolley loop back into the bus tunnel.
2. The abandoned Red Line yard tunnel, ending at the Bennett/Eliot intersection literally under the sidewalk. Punch through wall, go to stub-end platform with egress into station lobby behind the closed MBTA ticket windows (the only available access point from the new Red station to the old Red alignment).

The abandoned tunnel is conceptually nicer for service, but hasn't been studied on engineering feasibility so we don't know if there are blockers. Therefore, must provision for the bus tunnel as the safer fallback option.



You can even, as a Phase I, grin and bear it with a short 1000 ft. street-running section across the bridge and into Brattle Sq. to buy a few years' placeholder of Heath St.-level frequencies into Cambridge while you save money for the much bigger tunneling job across the river. Maybe even limit the street-running to just crossing the bridge and then ride through JFK Park on the surface and stub-out with platforms on the plaza walkway for a temporary surface stop. Not all that pretty, but with the Allston surface construction being relatively easy and the Charles tunnel costing 2-3x more than all else combined there's no reason to wait or build it all as a monolith if you can get a temporary-terminus surface branch built ahead of time. Phase it accordingly, but do front-load that surface construction without waiting on the tunnel.

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

Unfortunately there's not a lot of motivation to do some Big Cross-Cambridge Dig to link up the rest when building all the (mostly) surface projects does the job as well or better than trying to go for conceptual perfection with a tunnel down Kirkland.

• Grand Junction surface linking BU-Lechmere with run-thru to Sullivan-Airport.
• Harvard Branch linking BU-Harvard with run-thru from either Kenmore OR GC-Lechmere OR Airport-Sullivan-Lechmere.
• Porter Sq. extension of GLX Union Branch with run-thru from either GC-Lechmere or Airport-Sullivan-Lechmere.
• Red between Harvard and Porter for pinging between the Union Branch and Harvard Branch sets of service patterns...usually via the faster and less-crowded reverse-commute direction on Red.

Tally up all the options and work all the gears around flushed-up full frequencies on these network options and is there anything lost here by just grabbing all the available surface routes and working the transfers as robust as they can get? Is something very much lost if a cross-Cambridge trunk is done in lieu of the Ring along the Grand Junction and GLX to Porter precluding a lot of transfer flexibility? Quite possibly yes.


Keep in mind what the whole value proposition of the UR is in the first place: transfers, transfers, transfers, and cranking up the network effects of efficient transfers. It is not a route geared towards linear, end-to-end, one-seat commute trips through downtown with transfers only in the CBD between one linear trunk and another. Attach GPS trackers to every B Line rider door-to-door on their whole transit trip: buses, B, other subway lines, everything. Now see what the plot looks like after a service day of tracking trips. These facts will immediately scream out:

• Regardless of what buses or other lines funnel in you're going to see a single BC-Gov't Ctr. trunk traced in ultra-fat magic marker on the GPS plot.
• The plot will escalate to maximum thickness between Harvard Ave., Kenmore, and Park St. More or less peaking around the CBD's peak density.
• Everything pulls so overwhelmingly along one linear corridor that the traces of bus transfers into the B look like little more than static noise on the plot. Even at big Kenmore bus transfer because the number of people going straight through to downtown so dwarfs the number transferring from buses.

Now do the same GPS plot for the UR mainline. It's going to look completely different.

• The UR mainline will still be the boldest thing on the map, but it won't trace out anywhere near as thick as a prototypical subway trunk. No screaming-obvious outskirts<-->CBD, "inbound-outbound", increasing<-->decreasing density like that B plot at its fattest.
• Unlike the B plot which sustains its fattest patronage closest to downtown, the thickness of the Ring mainline's plot continuously waxes and wanes between certain high-demand stop pairs. There's no one center of attention because network nodes from multi-seat trips are driving the travel patterns, not linear "inbound-outbound" trips driven by the density high-point on the map. Most people are not going to be traveling on the Ring for particularly long stretches...just between dominant transfer stops. So there will be multiple demand peaks spread across the route map.
• Because of the more muted prominence of mainline trips on a circumferential route, those transfer stops that look like static noise on the B Line plot are going to proportionately look like big starbursts on the Ring plot shooting flying sparks in all directions. Chelsea, Sullivan, Kendall, Mass Ave., Harvard stops all look like lit sparklers temporarily outshining the Ring mainline itself because these two-or-more seat transfer trips are the dominant pattern on a circumferential route, and the combinations of highish-demand 2+ seat transfers gets thrown in a blender at these stops. This contrasts with the B Line plot where straight-to-CBD one-seats are so orders-of-magnitude dominant a travel pattern that great big Kenmore bus terminal gets lost in the glare.

It's useful to visualize it like this, because you can see a little more concretely how a circumferential route behaves way different from a linear route. It's all about the network effects, and the only thing that matters when building a circumferential route is hitting those transfer points of peak network effects. There's a natural tendency when looking at a 2D map in isolation to try too hard at tidying things up into fewer pieces and more linear/run-thru lines. Because it's what we're used to with the way the current system is heavily skewed to one-seat "inbound-outbound" and CBD as center of the universe. We forget that the subway was originally built around local transfer nodes and facilitating efficient two-or-more seat trips. We forget that post-BERy the subway got way worse at that job over time by too much MTA/MBTA target fixation on the CBD to exclusion of local transfers. And given that familiar first instinct is always "inbound-outbound to the CBD" it's easy to forget that more linear builds are not necessarily going to relieve that. Yeah, Red-Blue is a linear build that fills a big hole. But it's an oft-repeated misnomer that the pure linear North-South Rail Link is somehow going to take a big load permanently off Red and Orange. Quite the opposite: it's going to create 100,000+ all-new suburban transit riders and by sheer overwhelming volume throw 10x as many all-new riders on the NS, SS, and BBY subway platforms than it ever takes off.

The only way to meaningfully address this is by re-emphasizing some of that BERY-era transfer flexibility at local/non-CBD transfer nodes. Make two-or-more seat trips nearly as fast and frequent as the one-seaters by roping in more of those outside-CBD transfers that fell through the cracks Postwar. Complement the modern CBD-anchored trunks with circumferential service patterns that behave more like that GPS plot exercise with the "starburst" effect away from the CBD...not the "fat magic marker" effect of plowing another trunk right through the CBD. It is less about what you build in steel and concrete than about frequency and variety of service patterns spreading the field.


This Kirkland St. subway may look like an elegant map-based solution to it all, but it's not a UR replacement. It's attempting to be another flavor of conventional "inbound-outbound" one-seater that tries to do its job on a single killshot of a primary service pattern (even if there is wiggle room for some alt patterns), behaving little different than a CBD trunk with a singular "inbound-outbound" density peak. Only because there is no CBD-like singular density peak on a line built almost entirely radial, ridership's not going to behave as efficiently on a GPS plot as the line--and its ops plan--look on the map.

By shooting too hard for conceptual integrity on its routing this ends up leaving too many "starburst" transfer stops on the cutting room floor and voluntarily forsakes too much in the way of two-seat ride network effects. A unified Kirkland routing is not going to pull riders like the as-designed Ring route if Mass Ave./MIT and Kendall are substituted by the crossing of the just the 83/86 in Ward Two. Mass Ave./MIT, Kendall, Union, and Porter are all of relatively even heft as transfer destinations in/around Cambridge. As deputy alpha dog to Harvard none of those transfers are individually head-and-shoulders above the rest because the multi-seat trips served are so diverse. So something gets lost in translation if zeal for mapmaking integrity starts trimming too many destinations that behave like "starbursts" on that GPS plot.

It ends up more valuable to de-centralize away from a single route and start spreading more frequencies and service patterns around the map so all those Top 5 transfers in Cambridge get served on some trolley's destination sign...even if basic Cantabrigian geography dictates they all can't feasibly be served on the same trolley's schedule. It actually makes for a better-performing network to forget about games of picking winners and losers amongst transfer stops and simply work the scheduling variety for all it's worth. Seem counterintuitive? Well...think back to the GPS plot. The defining trait of the circumferential line are these "starburst" patterns where few two-seat trip combos at a transfer are ever going to stand out head-and-shoulders above the other two-seat trip combo in demand. And the defining difference from a conventional trunkline build is that the dominance of one-seat trips is so very much muted by contrast. Not counterintuitive at all, because you can see the demand's behavior with your own eyes on the GPS plot. So shouldn't that defining behavior inform how hard one squeezes the map for sake of one single routing vs. spreading the map for sake of schedules to all the major transfers?

Eyes didn't deceive the official UR planners when they traced out that northern route with its separate Harvard spur. Spreading the field with high frequencies and schedule flexibility to all the major "starburst" transfer stops nets the biggest overall payoff for what a circumferential route is supposed to do.

 

[Charlie_mta]

Ruggles (Orange Line) to Broadway (Red Line) Light Rail line via Melnea Cass Blvd. This would be part of the LRT Urban Ring.

Red is surface LRT, yellow is elevated, and green is tunnel, utilizing the abandoned trolley car tunnel above the Broadway Red Line station:

 

[CSTH]

I like it.

But hard to skip dudley. Why not put the LRT through dudley where there's already an active street level and a bunch of bus connections (taking space from cars on washington st and malcom x as necessary) and leave mama cass blvd for the cars?

Would love to know where it goes after broadway too...

 

[F-Line to Dudley]

You can save on some construction costs by doing simple duck-under at the Mass Ave. intersection from the Melnea Cass reservation, then back on a median reservation the length of Mass Ave. Connector to the Frontage Rd. intersection. The grass median on Connector is wide enough for a true grade-separated trolley reservation if you trimmed the double left-turn lanes into a single left.

Then do trolley viaduct straight over Widett Circle (we'll assume the Food Market gets relocated to Marine Terminal in this scenario clearing the straight-across airspace). OR...realign the Haul Rd. viaduct on that alignment to connect straight to Mass Ave. Connector, which would be a lot better for the truck traffic than the current staggered intersections and would help justify the cost. Trolleys run mixed-traffic running with the trucks only, then turn out at Dot Ave. into a subway portal popping out at the bridge abutment. Traffic signal @ the turnout. Between the Melnea Cass reservation and the restricted truck traffic you've got your contiguous transit traffic priority the whole 2 miles from Ruggles to Dot Ave. That's almost as long as the C Line reservation, but with many fewer intersections and traffic lights...so pretty good value and ops manageability.


From the Dot Ave. turnout it's 500 ft. of all-new tunneling to A St., then you're inside the old Broadway upper-level trolley tunnel. Reconfig the mezzanine to the side, since it claimed a small portion of the trolley tunnel during the 1988 station renovation. Pop out at the Foundry St. portal then figure out the rest. You'd need to make your way back to Haul Rd. to make a BCEC stop and get to Silver Line Way and the Transitway, but that requires negotiating way around Gillette HQ. I don't have any elegant ideas there, but there's more than one way to do it without excessive back-tracking so shouldn't be terribly hard.


Silver Line to Dudley would have to be converted to light rail as well as the Green Line-Transitway connector to give you an equipment feeder, but otherwise you've pretty much drawn the SE quadrant Urban Ring as the official plans envision it. Just keep the viaducting to a minimum by grabbing the Mass Ave. Connector median and use Haul Rd. for all it's worth so the steel-and-concrete construction is minimized to where it matters most (i.e. the Broadway station interface, and possibly the back-track to Seaport) and not one excess tunneling foot more. Headways here are not going to be anything close to Central Subway levels, so this is a relatively easy alignment to dispatch as a mostly reservation + Haul Rd. -runner.

 

[Charlie_mta]

Would love to know where it goes after broadway too...

A fairly straight shot to the Silver Line tunnel next to South Station could be possible, if future development of South Station Tower and the Post Office would be designed to accommodate it.

Red is surface, yellow is elevated, and green is tunnel. Blue is the existing Silver Line tunnel.

 

[Scalziand]

Oh dear.

F-line sanity loss in 3...2...1....

 

[F-Line to Dudley]

A fairly straight shot to the Silver Line tunnel next to South Station could be possible, if future development of South Station Tower and the Post Office would be designed to accommodate it.

Red is surface, yellow is elevated, and green is tunnel. Blue is the existing Silver Line tunnel.

1000% No-go.

1. Surface is right on top of SSX. That's all claimed and, politics willing, bulldozed within 5 years and ready to have fresh track laid.
2. Tunnel portal fouls the roof of South Station Under when the N-S Rail Link gets built.
3. Can't shift anything closer to Dot Ave. or portal-under before the surface CR tracks fan out, or else everything NSRL-related gets blocked.
4. As described a million times over in the various NSRL discussions...it's not an either/or of deferring SSX to build NSRL instead (no matter how many times Seth Moulton quotes inaccurate info). SSX + NSRL are the 100-year capacity solution for running Euro-frequent mainline rail, so both will be there double-barreling at full tilt in the year 2100 A.D. That footprint will never be available.
5. Insertion point into the Transitway clips the cornerstone of the century-old SS building, needs to be moved back. If moved back, too close to the bus loop and inadequate sightlines for a bus driver coming around the loop to see a trolley coming in at sharp angle. Too much sideswipe risk in a constrained tunnel under high-voltage wires for that to be allowable when bus vs. trolley will--every time--wreck the bus that's looping with the worst sightlines of any vehicle at this spot. There's not going to be any sort of auto-stop signal system preventing that crash risk in a tunnel where trolleys and buses have to co-mingle; it's all line-of-sight / operator control here, even if the rest of the Green Line gets a next-gen signal system. So we aren't out to prove bragging rights that it's physically possible to construct a tunnel that threads the needle between the building cornerstone and the Big Dig ramps. This thing is a transit mainline that has to be safely and fluidly operable for 2 different modes co-mingling at high frequencies and tightish vehicle spacing. What works line-of-sight on the Transitway's straightaways isn't going to work by the loop where everyone will have to take a 10-second auto stop at the merge to check the mirrors around a blind corner to make sure another vehicle isn't blowing a red.

#5 has come up before in a bunch of Crazy Transitway Pitches that have tried to take the hardest humanly possible tunneling paths from South End to the Transitway for...I don't know, boredom's sake? But even though that's got plenty of drawbacks to it...it's still the least of your worries because you can't even get past the Pike vent building before SS surface and every NSRL provision blocks it solid.

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

This also confuses the Urban Ring mission statement a bit. UR is a radial line. Nowhere in the official proposal does it intend to give a one-seat ride to one of the Big 4 downtown transfers or the two CR terminals.

^^This is intentional.^^ It's for high-frequency facilitation of two-or-more seat trips: quick-hit with constant ridership overchurn to last-mile neighborhood buses and intersecting rapid transit spines as you move around the ring. With the network effects de-congesting the local buses and allowing Yellow Line frequencies to scale up across the system (here it comes: "It's the frequencies, stupid!"). Hardly anyone is going to do an end-to-end trip strictly on the ring. Therefore, there's no need to distort the map by reaching straight into the CBD.

People who need to go to South Station will transfer to Red at Broadway (or Andrew if Southampton St. gets used instead of Mass Ave. Connector). Your main goal is to provide quick trips from the system's largest bus terminal to Southie and the Seaport, and tie the other end of that quick-hit trip around this SE ring quadrant to SL1-Airport. Therefore, you need to have this on a direct trajectory to Silver Line Way first, SS last (if at all). If you plow it to SS first you're building something entirely other than the Urban Ring, because Southie and the Seaport end up ceding the quicker schedule and a whole lot of frequencies to regular old CBD crowd-swallower slots straight through the gut. That's downtown-centric Silver Line Phase III, not radial UR.

With that in mind, remember that the only way you can physically get the trolleys out here is to first have connections to the rest of the system that supply the equipment for this route. So by necessity you've already built the SL III replacement between Boylston and the Transitway and the SL-Washington replacement branch to Dudley before you're capable of laying a single length of rail on that Melnea Cass reservation. There's no potential yard space or ops base to run this threadbare in semi-isolation; it'll need an equipment pipe at both the Dudley and SL Way ends. (Which probably means you'll have a transitional BRT starter era on this route while that Boylston-SS subway megaproject chews up attention).

So given those as ironclad prerequisites you have no need to try to split the difference on routings. You will already have your 3-car crowd-swallowers running from Medford to Downtown to SL Way handling the CBD crowds, so the radial route--now furnished with its trolley supply via both Dudley and SL Way ends--can be strictly a radial.


Now...when operating it you don't have to terminate at SL Way. You can send it through the Transitway to loop at SS on the arse end of the trip for pure equipment cycling. But that's an ops semi-necessity that chucks in some minor value-added...not the main attraction, because you already have a Transitway-CBD main attraction. The schedule on the radial run doesn't hit "showtime" until it's outbound of SL Way.

 

[Charlie_mta]

As an alternative, this route would be a relatively cheap route for LRT. It would connect an LRT Urban Ring to the Silver Line tunnel, then to South Station in the existing tunnel.

Red is surface, yellow is elevated, and green is tunnel. Blue is the existing Silver Line tunnel.

 

[F-Line to Dudley]

As an alternative, this route would be a relatively cheap route for LRT. It would connect an LRT Urban Ring to the Silver Line tunnel, then to South Station in the existing tunnel.

Red is surface, yellow is elevated, and green is tunnel. Blue is the existing Silver Line tunnel.

Still conflating SL III with UR here. The Seaport transfer of utmost importance to the radial line is SL1...and to lesser extent the 7 bus or any reanimated City Point trolley. Not Red. Anybody riding the Ring who wanted to get to the CBD would've hopped on a rapid transit transfer long ago and gotten there sooner. And there's no need to split the difference with mainline Transitway frequencies because Green is already pumping that full of headways from Boylston as your prerequisite for having available trolleys for this route in the first place.

Other than that BCEC stop the prime attraction here for people riding eastbound out of Ruggles/Dudley is that bang-bang transfer to the Airport at SL Way right next to that Ted onramp...not back-tracking to Courthouse or SS and going upstairs/downstairs to come back from whence you came 10 minutes later. There's no need to blow a $$$ wad tunneling into semi-duplicate service. Stay on Haul Rd. all the way to SL Way. Max out the value of that SL1 transfer. Get within walking distance of Design Ctr. If there's a short Green Line branch out of SL Way down Summer St. to City Point augmenting or replacing the 7 bus, take advantage of that additional cross-platform transfer at SL Way so the folks in the heart of Southie get their bang-bang fast transfer option out to Dudley. It accomplishes its goals best if you DON'T do any tunneling except for that boomerang back from Broadway.


Second, besides being unnecessary...that insertion angle into the Transitway is severe enough that you're going to have another blind-angle tunnel merge forcing all tunnel traffic to pause while operators check a mirror to make sure other traffic has stopped. It's not nearly the safety issue as with the very blind bus merge at the loop, but it's a toilet clog nonetheless in a tunnel where buses and trolleys have to single-file it at tight but safe spacing line-of-sight to the next set of taillights in front in order to keep things moving. Can't be introducing automatic red signals for blind spots or everyone's headways suffer. No matter how logical it may look on a 2D map, you won't like the consequences from every route's service levels taking a hit by introducing a bus-on-trolley Copley Jct. kludge smack in the middle. Going the extra 2500 ft. down Haul to SL Way will carry more seats/passengers per hour through the Transitway than the junction alternative that forces headway cuts. It'll hurt mainline throughput, and you can forget about ever having the capacity to do that easy-grab City Point branch.


Other. . .

• The W. 2nd back-track from Broadway looks pretty good! You might have to widen out the half-loop a bit because by the time you've left the station lobby you've pulled off the top of the Red Line tunnel, meaning when you cross back over it you need to intersect at a pretty clean (if not completely 90-degree) angle at the Dot Ave./W. 2nd intersection to minimize the construction impacts. Might require a little bit more meandering onto the Red Line yard property by sweeping the loop under the Foundry St. driveway/employee parking area. Won't be a problem for NSRL as the Old Colony lead tunnel will hug the commuter rail--not Red--tracks so it can slip under the Pike where the Pike tunnel's at its absolute shallowest by the HOV portals.

• Given that you'll be waiting awhile for those Boylston-Transitway and Boylston-Dudley builds that supply the trolleys for this thing, we're also on timetables long enough that you never know what Gillette's plans are going to be for that sprawling one-story HQ. If they ever want to part out manufacturing to the 'burbs with corporate staying in town they could very well cash out that property for something tall. Then the street grid will almost certainly be stitched up to bring Richards/Cypher out to intersect Dot Ave., subdividing the parcel. If and only if something like that happens, then you'll have a much better/faster trajectory out of Broadway via Richards (and clean 90-degree intersection with the Red tunnel when passing back over). So consider that a semi-fluid situation at the timetables we're looking at for introducing trolleys on this UR segment.

 

[Deetroyt]

For this SE quadrant of the ring, could trolleys from Huntington ave hook a turn onto Ruggles Street? Close this street to everything except these trolleys from 6-10am and 4-730pm, and have the LRVs share the bus drop off area. Trains could then turn right out onto Melnea Cass towards Dudley/Seaport. Would this be feasible assuming the ring is someday introduced as light rail?

 

[F-Line to Dudley]

For this SE quadrant of the ring, could trolleys from Huntington ave hook a turn onto Ruggles Street? Close this street to everything except these trolleys from 6-10am and 4-730pm, and have the LRVs share the bus drop off area. Trains could then turn right out onto Melnea Cass towards Dudley/Seaport. Would this be feasible assuming the ring is someday introduced as light rail?

Maybe. Ruggles east of Huntington could be reservation'd if the abutters are OK with reconfiguring the road and eating some of the tree barrier on the north side so the road can get its grade-separated center reservation matching Melnea Cass. Then you can claim the little wedge-shaped park next to the Wentworth athletic field to square the turn onto the E at MFA station.

Problems:

• That's not really the Ring route because it whiffs on Longwood and bends back into downtown via Copley as a necessity for getting the trolley supply. It's a start, but the other shoe has to drop with due haste or it's not really doing what it's supposed to. You already have the much higher-demand Downtown-Dudley branch going up Washington, remember...so this E cutover won't stand on its own unless the follow-up Phase II is imminent.

• Banging a left instead @ Huntington through Longwood, Brigham Circle, and a D-to-E connector at Riverway starts swimming against a stiff tide on feasible headways due to the E's max capacity through the street-running section. And you're going to have a more limited car supply to choose from going west vs. Downtown where the E is fed by GLX Brickbottom carhouse. Want adequate headways...must unsatisfyingly sacrifice Longwood + Kenmore to a later fix. Want the complete checklist of Ring destinations...must whack headways because car supply more limited and Huntington traffic poses some limitations to going too dense.

• Oof!...any further western progress on the final SW-quadrant Ring that fixes the ^^above^^ glitches is brutal. Absolutely brutal. Louis Prang St. is narrow. Banging-left onto Huntington to Brigham Circle and banging-right onto Longwood Ave. runs into the same headway headwind as above, plus Longwood Ave. is even more narrow than Louis Prang. Plowing due west through the Emerald Necklace to meet up with the D for a phat supply of headways isn't going to fly with pedestrian accessibility to the Necklace or the Muddy River floodplain which is going to be getting much worse as sea level rise limits Charles Dam's ability to flush the basin system full-tilt after a storm. Tunneling due west is doubleplus no-good for the same street-width and 20-year flood risk constraints.

• There's no completely elegant routing, period, for the SW Ring quadrant, even on BRT. Look at how fuzzy it gets on the official T map between Longwood and Kenmore. We're just throwing shit at the wall now trying to look for something that competently works for ops and accomplishes enough checkboxes on demand served, even though it's guaranteed to be fugly-looking on a 2D map.

• Still must have car supply at each of the intersecting nodes--Huntington, Dudley, and SL Way--because there's no place for a yard anywhere along this quadrant. So still looking at a BRT bridge era while light rail replacement on Washington and the reeaallly hard/expensive and super-critical Boylston-Transitway connection get built. Relative build ease of hooking in at MFA and reconfigging the wide roads points-east for reservations doesn't tell the full story. It's still firmly entrenched as a #3 pecking-order project with two very critical equipment-dependency builds outranking it.

None of that's fatal. Save for that Southampton/Andrew vs. Haul/Broadway/back-track decision we pretty much know where this thing is going all points east of Huntington to the Seaport, and exactly what reservation measurements (i.e. quite enough) and co-mingled traffic (i.e. Haul Rd. trucks) we've got to play with. It's that blasted SW quadrant from hell that keeps this thing semi-crippled without a clean solve for reaching Kenmore, and the equipment supply prereqs that require stretching out the timetable to a lot further future than grab-n'-go. Though doing the same reservation construction for the BRT bridge era can make conversion to trolley a hell of a lot easier/cheaper/faster when the equipment feeders finally touch and it's go-time.

I guess embrace that BRT bridge to buy self time, and just make sure wide Melnea Cass and wide Ruggles St. get their reservations configured right from Day 1. That buys you a plenty-robust route and the time to figure out on-the-fly the build sequence for getting those prereq trolley feeders. And buffers the painful trial-and-error for nailing down a workable Huntington-Longwood-Kenmore route that doesn't suck too bad, can go trolley without excessive compromises, and doesn't cost a billion dollars of tunneling with wanton destruction to abutters and natural resources in order to go trolley. Just accept the need to stare down the "Please Pardon Our Appearance" BRT era on this segment as necessity for getting things done...but providing useful service while you're figuring out how to get things done.

 

[DominusNovus]

If it were reasonable to bore down below all the current T lines and build a new one from scratch (so, ignore the geological problems for sake of this question)...

What route would you go with?

 

[Shepard]

That's a crazy but thought-provoking question. I like it!

My preference is generally for the New York approach, where lines - or major segments of lines - follow over or under the main commercial streets. Of course, that's generally easier with a grid, but I think there are some routings in Boston that would or could work. A Mass Ave line, for one. A Washington Street line - basically the old Orange Line - would be another... extend that today to be Franklin Park Zoo via Dudley and South End to Everett via Charlestown. The old A line was similarly very logical, as is today's C and E lines. Medford to Seaport could have been a fairly straight shot via Route 28 in Somerville and Congress Street downtown. I often believe that turning these logical "straight shots" into heavy transit corridors would have made the city much more navigable and intuitive, not to mention more useful for transit.

Anyway. It's hard to answer outside of the abstract because the possibilities are literally endless, but it really does make you think: would a system designed today go out to Braintree? Or Riverside? Would it be more concentrated in the urban core? More hybrid-commuter like DC? Very interesting to consider.

 

[F-Line to Dudley]

This would be the reference to bookmark for ID'ing those street corridors: https://en.wikipedia.org/wiki/Boston-area_streetcar_lines. And this: https://upload.wikimedia.org/wikipedia/commons/9/96/1925_BERy_system_map.jpg. Our old streetcar network. Most of the numbers still corresponding to bus routes today. Remember...we've always been a square-to-square travel patterns type of city...not a grid like Manhattan...so the Point A-to-Point B demand patterns really haven't changed very much at all and need almost no major philosophical re-think a la trying to impose NYC-style subway gridding on Boston's cowpaths-begat-squares. So little has changed, in fact, that the routes themselves follow almost exactly the same streets with exactly the same route numbers on the Yellow Line as they did on streetcars and horsecars before we ever built the subway. If it's not a New Boston neighborhood like the Seaport, history--not wild out-of-box reconceptualizing--is your guide.

Where we need to get back to basics is FREQUENCIES. The Yellow Line has to stop being a shameful stepchild. And the places where we do need rapid transit augmentation are simply frequency increases by a different and more capable mode. Sometimes requiring expensive steel-and-concrete and...yes, maybe some tunneling. And sometimes not needing more than a better-organized and suitable-to-task surface corridor. That's it. No need to re-draw the whole damn city out of Manhattan-on-the-brain when the city organically works and has always organically worked. Just fix the transpo frequencies and capacity that hasn't kept up with the times on these square-to-square patterns.


Bus routes (approx.) that used to run through the Central Subway (portals bolded):
92 -- Sullivan, Main St., North Station, subway (to 1949)
93 -- Sullivan, Bunker Hill St., North Station, subway (to 1948)
69 - Harvard, Cambridge St., Lechmere/North Station, subway (to 1922)
87 - Clarendon Hill, Broadway, Lechmere/North Station, subway (to 1922)
88 - Clarendon Hill, Highland Ave., Lechmere/North Station, subway (to 1922)
Silver Line -- Dudley, Pleasant St., subway (1938)
43 -- Egleston, Pleasant St., subway (1956/1961)
9 -- City Point, Pleasant St., subway (to 1953)
60 (partial) - Brookline Village, Huntington Ave./Boylston St., subway (to 1932; current 60 west of BV was out of BERy district, required transfer @ BV)
60 (partial) - Cypress St., Brookline Ave., Kenmore, subway (to 1932)

Note: that Dudley route on present-day Silver Line and the 2 Sullivan routes used to be matching subway pairs replicating the Orange Line El with denser streetcar stop selection.


Harvard Sq. bus tunnel trolleys (run-thrus to other subways bolded):
77/77A - Harvard, Arlington Heights (to 1958)
71 - Harvard, Watertown (to 1958)
73 - Harvard, Waverley (to 1958)
72 - Harvard, Huron Ave. (to 1938)
1 - Harvard, Newbury St./Green Line surface transfer (to 1949)
69 - Harvard, Cambridge St., Lechmere/North Station, subway (to 1922)
68 - Harvard, Broadway, Inman, Kendall, Charles Circle, Cambridge St., East Boston subway, Maverick, Jeffries Point (to 1919)


I won't list the Maverick/East Boston/Revere routes because the Blue Line extension replicated them pretty well, and all the Lynn/Chelsea/North Shore routes were out of the BERy district. We know how important Lynn terminal and the North Shore are to hit.



We don't have to think too grand here about firing up the TBM.

• The 87 and 88 are well-augmented by building GLX.
• Silver Line-Dudley should've been a GL branch from Day 1, and we can right that wrong any time we want by refurbing the Tremont Tunnel with a Tufts Med. Ctr. intermediate station.
• The 43 gets its difference split pretty well flanked by Green to Dudley on one side and existing Orange on the other.
• City Point gets re-enabled if we build the Green Line-Transitway connector connecting Silver Line Way to Boylston.
• 92/93 get augmented by Green at both the Sullivan and NS/Haymarket ends by building out the Urban Ring. And, yes, a reanimated Dudley-Sullivan/Ring pairing would have a lot of demand.
• The 60 variants are replicated by D-to-E connecting streetcar track allowing boosted Huntington Ave. headways via Brookline Ave. short-turns and run-thru options to Kenmore Loop. This also traces out a chunk of the SW quadrant of the Urban Ring (mode TBD), so could much later be subwayed if you can find a coherent way to do it.
• Red-Blue serves up all the frequencies imaginable replicating that insane 68 routing from Harvard to Eastie.
• Red Line to Arlington Heights rapid-transitizes the outer half of the 77 just like the Alewife extension did for the inner half.

Comb deeper still. . .

• The 66 gets its load shifted around in a big way with the Urban Ring + Harvard spur.
• Indigo-Riverside + a short 71 extension to Newton Corner super-sizes the Watertown-Harvard corridor.
• Indigo-Fairmount + strengthened E-W bus frequencies strengthen the network effects in Dorchester.
• Red to Mattapan + Green to Dudley + Indigo-Fairmount anchors both ends of the 28 corridor and allows you to dust off that 28X-Blue Hill Ave. proposal in a big way.
• Look how clearly you can trace the SE quadrant Urban Ring on the 1925 map via Dudley, Southampton St., Andrew, and Southie/Seaport. That was even before the forces of urban renewal "gifted" us Melnea Cass Blvd. as an I-695 byproduct.

It doesn't change any of our build priorities, really, because the square-to-square travel patterns have been so rock-stable for >100 years. The only thing that's really been reshuffled is build priority order from modern congestion and development stressors. Otherwise, we know exactly what we have to do. GLX, Red-Blue, Downtown-Seaport, Urban Ring, the Indigos, the Crosstown buses, the two-seater frequency boosts.

The only two big desireable links we can't really build are:

• That Mass Ave. subway under the 1. For many, many cost, climate change, and geological reasons.
• A Lechmere-Harvard connector uniting the Green Line with the Harvard bus/trolley tunnel & routes. Was briefly considered up Cambridge St. via Inman 100 years ago and would've changed the face of the system, but never quite came together. Would've been nice to have an Inman subway station, but given all we're capable of triaging via the Urban Ring, UR Harvard spur, and taking GLX through Porter we're never going to be at a loss of new and incredibly useful ways to link pieces of Cambridge together via other corridors. This simply isn't an omission worth getting hung up about while Allston-Harvard so badly needs a link and Porter still beckons the Union Branch (nevermind far-future possibilities past Porter on the Watertown Branch augmenting the 70 & 71).

...and then there are some obvious concessions like no Washington St. grade separation because we stupidly blew up the El and tunneling's too disruptive, and the southern-half Urban Ring not having a street grid suitable for tunneling through Longwood. Tactical nuclear strikes for perfectionism's sake just have to take a knee here for 50-75 years until we get all critical moving parts of other megaprojects done first.

 

[DominusNovus]

F-Line(or anyone else interested), if you'll humor me, allow me to pose this addendum:

Again setting geology aside, you have the opportunity to bore a new subway tunnel for the city, but it has to follow under one of the existing lines. What line receives this addition?