Crazy Transit Pitches

[George_Apley]

Not sure what the problem is here. This thread seems to sustain itself pretty well all by its own ebb and flow through minding all 3 words in the title. So does the "Reasonable" Pitches thread. Maybe we just need a third "Institutional Transit Pitchery" thread to serve the action part of the Big/bold/necessary game-changers and fully-vetted "Crazy" thread graduates that need their real-world next steps dissected. No moderator is stopping anyone from being that thread-starter if there's an unmet discussion need begging to be filled.

I think the Green Line Reconfig thread serves that purpose well enough. Threads such as that serve that need, and we should create them as discussion leads us to more "concrete" planning.

 

[BostonUrbEx]

Pitch: Remove the Braintree Branch of the Red Line and replace it with a mixture of commuter rail and DMU services.

Problems:

• Ashmont Branch needs more capacity and service
• Braintree Branch needs more capacity and service
• Old Colony Lines need more frequent service
• The Red Line/Old Colony/I-93 right-of-way is tapped out without [expensively] going vertical
• Malfunction Jct between JFK/UMass and Andrew Sq consistently provides scheduling and service issues for the Red Line

On our side:

• Braintree Branch stations are fairly well spread and have a fair amount of distance between them
• Old Colony Lines are immediately parallel to entire Braintree Branch
• Ability to triple- or quadruple-track the enhanced Old Colony trunk if and when necessary, and still allot space for stations

Specifics:

• All Red Line service is strictly Alewife-Ashmont at maximized headways
• Addition of a station at Pope's Hill/Neponset for DMU service
• DMU service would cover all Braintree Branch stops at existing frequencies
• All Greenbush Line service would be added frequency for all stops in Quincy
• All Old Colony Line service will make stops at Quincy Center
• Select Old Colony Line service will make stops at Braintree
• All services will stop at Quincy Center and JFK/UMass

Problems:

• Requires Proof-of-Payment system and fast/efficient/easy transfer to Red Line at JFK/UMass and to both Red Line and Silver Line at South Station
• Should select services fork at Track 61 to BCEC and the Seaport?
• Can a JFK/UMass transfer handle the number of people who may want to transfer to Red Line coming inbound?
• Will the North-South Rail Link be required, or is South Station expansion enough? If required, will an Old Colony portal for NSRL also be necessary?

 

[F-Line to Dudley]

Shear off Quincy from the DTX and Park transfers, Kendall, Central, Harvard Square, and Davis???

Impose a maximum allowable 15-minute headway...6 minutes worse than today's headways???


Dear God, why??? That is tantamount to taking a steaming dump all over Quincy and Braintree transit. No...just no. There is absolutely, positively no advantage to a mode change that offsets how unacceptable, untenable, and unfixable all of the downsides are. Indigo + NSRL is not Red. Not in a billion years.

 

[JeffDowntown]

Shear off Quincy from the DTX and Park transfers, Kendall, Central, Harvard Square, and Davis???

Impose a maximum allowable 15-minute headway...6 minutes worse than today's headways???


Dear God, why??? That is tantamount to taking a steaming dump all over Quincy and Braintree transit. No...just no. There is absolutely, positively no advantage to a mode change that offsets how unacceptable, untenable, and unfixable all of the downsides are. Indigo + NSRL is not Red. Not in a billion years.

I think you just validated that the pitch was truly crazy.

 

[BostonUrbEx]

Impose a maximum allowable 15-minute headway...6 minutes worse than today's headways???

Not sure where you even pulled this from, to be honest.

 

[F-Line to Dudley]

Not sure where you even pulled this from, to be honest.

http://www.mbta.com/uploadedfiles/D...equency-schedule.pdf?led=3/24/2016 6:38:34 PM

Rush hour headway on Braintree Branch: 9 min.
Midday headway: 14 min.
Evening/late night: 12 min.
Weekend (all): 14 min.

Fairmount Corridor Feasibility Improvements study specced a densest achievable headway with DMU's at 15 minutes, limited to that by FRA-reg turnaround tasks, South Station dispatching, and the 1-1/4 mile trip through the terminal district between platforms and the start of the free-running portion of the mainline. All of those calculations for Fairmount apply to Old Colony because they spend equal time and distance through the same area of the terminal district.


Under no circumstances will a mode change to mainline rail provide equal headways. Including in a NSRL universe, because the same terminal district will be replicated underground at the 3 southside line merges. At rush hour headways will be 40% worse than Red Line. In addition to cutting off Quincy and Braintree passengers--and the South Shore's primary bus terminal--from direct access to Park + DTX transfers, Cambridge, and job destinations at those stops--and not at SS or on the route of the NSRL--actively commuted to by thousands of daily Braintree Branch riders.

That is catastrophic transit loss for a branch whose 5 unique stops produces 30,000 daily boardings...5% more than the entire Commuter Rail northside combined, and almost two-thirds the boardings of the entire Commuter Rail southside combined.

 

[Upstruk]

[/IMG]

Here is a crazy transit pitch to send a light rail line starting from the Tremont Street Subway, continuing to a new transfer station with Orange at Tufts. It then crosses either over or under the orange line and under the Pike. Next it continues under Herald Street (at station could possibly be built at the Ink Block) and emerging from below under the I-93 elevated ramps. Refer to the street view in the link. The route would be on the ground below this ramp (emerging from underground where Herald meets Albany St. https://www.google.com/maps/@42.3456821,-71.0596793,3a,75y,223.09h,71.78t/data=!3m6!1e1!3m4!1sS5jMGlxm-bo_zh5QYt2N4Q!2e0!7i13312!8i6656!5m1!1e2?hl=en

Next the route travels over a new bridge and enters into the existing Broadway trolley tunnel portal (MBTA emergency training center on Foundry St) above the Red line. Here the training center is restored to its original purpose as an upper level transfer station above the Broadway Red Line. The route continues through the existing tunnel until it ends and is extended under 5th street until it emerges through the retaining wall into the South Boston By-Pass Road trench. From here the route would be street running to the D street portal into the Silver Line Tunnel. The street running route would serve the expanded convention center, D street development and the yet to be developed land along Pappas Way.

This scheme provides transit to the parts of the Seaport which are currently the least accessible and creates a whole new transit corridor through the north sides of the South End and South Boston. The tunneling is limited and is through areas which appear to be "easier" to tunnel. The portals all work with the existing grades and therefore do not require a steep incline.

 

[stefal]

I believe where you put the bridge over that section of commuter rail line tracks is provisioned for decking, (F-Line probably knows, I think he's mentioned it before during the whole B24 fiasco) so running a bridge through it may not be ideal, unless you can somehow align it so that it lines up with transit-oriented-development that is decked over those tracks. That'd be quite an expensive and complex task for a developer, though.

Since this is crazy transit pitches, it may be best if the tracks were buried, from under Herald Street, across the tracks, and tying in with the existing portal. That'd be quite a feat, and I'm not entirely sure if its possible.

 

[Upstruk]

Here is an expanded view of the proposal showing how the route could work with the rest of the T network.

Instead of connecting the Green Line to the Silver Line Transit Way at South Station this pitch makes the connection at the D Street Portal.

While Courthouse station is fairly far from Boylston Station the eastern end of the Seaport and the future development opportunities along Pappas Way would be equally close to Boylston compared to if the connection began at South Station.

The advantages include a new transit armature for development along D street (the routing could also be down a rebuilt E Street), tunneling through narrow older streets and passing under and along side the I 93 tunnels is avoided, and the required tunneling sets up a route to run light rail down Washington Street to Dudley.

This pitch would not preclude the pitch to connect the Green Line from the Tremont Street Tunnel to South Station Via Tufts.

 

[F-Line to Dudley]

Absolute no-go on that routing. It would block the path of the Old Colony/Fairmount lead tunnel into the N-S Link, which has to slip below the Mass Pike tunnel. No one will ever allow a build that kneecaps NSRL like that.


Second, this spot next to where the Bass River gets covered over and where the old South Bay was landfilled is also the #1 worst 50-year flood-risk spot in all of Boston. The upper half of the Haul Road/Track 61 cut is already a major concern for the 'storm drain' effect dumping an additional canal's worth of water into an already inundated Widett/Cabot area. Put a portal there at that singularly vulnerable spot and all you are doing is building an even higher-capacity storm drain further inundating the also-fucked South End. Required flood mitigation costs for installing multiple sets of flood doors and thicker walls to seal the tunnel against a catastrophic breach will pointlessly double the cost of this routing. It is not "easier" tunneling. It is harder and more expensive, because all the ones that avoid South Bay by sticking north of the highway ramps avoid all the required expense for Netherlands-grade flood controls.


Third, the extra mileage and street-running of the Dorchester + South End jog serves no known demand pattern. It triples travel time from the Downtown transfers to South Station and the Seaport, which is the primary goal of SL Phase III's intended load relief on the Red Line. Chucking the schedule out the window with a distended route running backwards through the more diffuse stops first before hitting SS at the end blunts nearly all congestion mitigation benefits from a Downtown link that hits SS first. If the SS-DTX/Park double-transfer is always going to be 7-10 minutes faster than the one-seat meandering more miles through 6 or 7 lower-demand stops before hitting the main course, people are going to stick to the same Red transfer dance. And downtown dwell times at the big transfer stations will continue to strangle all mobility in town, thus flunking the #1 value proposition of Silver Line Phase III & variants' very existence.

Broadway and its walking-distance catchment already has much faster access to South Station, Seaport, and downtown by Red + transfers. Or just walking. They will not be drawn in nearly large enough numbers to offset the other losses from choosing the meandering routing. Very different story for the Urban Ring since Broadway's on a straightest-trajectory shot from Dudley and the roads best-equipped to trace out the SE quadrant of the Ring. But Broadway being a good Ring stop does not mean it's a must-have for the Seaport/SS-Downtown connection worth warping a map over. The demand audience is empirically distinct and different.




Upstruk, I appreciate the effort and detail you're putting into these renders...but it's falling straight down the trap where the "Crazy" totally sidelines the more important "Transit Pitch" part and just clogs page after page full of dartboard throws. There has to be some sort of demand rationalization backing a proposal. Modifying an ID'd demand corridor into worse transit because pieces of flotsam on a map may be technically available to stitch together isn't good transit when it doesn't address a question being asked.

And throwing feasibility scoring completely out the window to prove the theoretical technical correctness of a routing in a demand or mitigation vacuum isn't providing a solution, it's practicing bad civil engineering. Civil engineering doesn't exist in a vacuum. Every structure interacts with its interconnected environment, be that mitigation on other abutting structures, the water table in the soil, or safety regulations set by law. And impact their environment on a sliding scale of solveables (e.g. moving a 93 emergency exit hatch 200 ft. down the road) to improbables (e.g. blowing up buildings in tactical nuclear strikes, getting safety laws changed). It's a ledger of benefits and demerits producing a cost-benefit calculation. Which then usefully produces an empirical ranking of Alternatives.

Tape-measured tunnel dimensions do not inform cost, ease, or legalities in a vacuum. When a routing officially studied has been fully-vetted with engineering scoring, the weak scores don't automatically get nullified by drawing a 2D diagram taking a different path...then concluding: "By the absence of the same path, I have an absence of that path's poor-scoring impactors. Thus, this is a superior routing."

No. All you have is an absence of scoring by removing the notion of scoring entirely from the vetting process. Every new render that follows in the footsteps of that fallacy is going to fail for the same reason: you can't determine empirical feasibility by removing the surrounding civil engineering environment from the equation.

 

[Upstruk]

The flood map you linked shows that virtually every trench in Boston has a 6' or greater flood risk. This includes the existing Silver Line D street portal, the existing orange line portal from the pike, a future portal in the pike trench to Washington street, the south west corridor orange line, the pike trench through Boston. Basically everything.

 

[F-Line to Dudley]

The flood map you linked shows that virtually every trench in Boston has a 6' or greater flood risk. This includes the existing Silver Line D street portal, the existing orange line portal from the pike, a future portal in the pike trench to Washington street, the south west corridor orange line, the pike trench through Boston. Basically everything.

Yes...and that's a big problem that'll require big and expensive retrofits on the existing tunnels and big and expensive flood controls baked into the NSRL portals.


Now why does this proposal intentionally choose the longest possible tunnel routing that stays inside the footprint "Noah's Ark"-blue of maximum risk? Do you see what I mean about throwing engineering scoring out the window to chase proof-of-concept notions of hardest-possible build? Just because SOME structures take on a big risk at one spot as necessary cost of doing business does not mean the playing field is automatically leveled for ANY structure to jump off the deep end taking on ALL possible risks like the existence of other structures in a risk area nullifies the risk. That's not how civil engineering works.


Take the North-South Rail Link, for comparison. The NSRL stays completely dry on the flood map in all these spots: South Station Under, the tunnel merge at SS Under, the mainline tunnel between SS and Central Station. Awesome. It stays inside the least-severe 2-4 ft. yellows and oranges all these other places: northside portals @ Boston Engine Terminal, Old Colony/Fairmount portals minimum @ Southampton, North Station platforms. Okay, not-so-awesome...but a hell of lot better than it could've shaken out on a flood map that all-around terrifying. The NSRL's optimal service routing can afford to take on all the extra cost and complexity of installing Netherlands-grade flood doors at "Noah's Ark"-blue NEC portal and double-up the protection from wall leakage on those 2 hairy mainline spots between Central Station and North Station because everything else on the build clings to the path of least possible mitigation. No engineering through an old built-up city is ever going to score a perfect 100...but the chosen routing for NSRL accomplishes all its service goals while avoiding far more flood risk than it takes on. The CA/T served it up that way by-design, and there really aren't any lines that can be redrawn on a map that balance cost/benefits any better than the current Link plan.


You can't say that for a 2D render that starts:

1. high-and-dry at the old Tremont Tunnel on the 1897 portion of the Green Line historically immune to major flooding
2. heads straight into the nearest dark blue max risk region, exposing that flood-immune 1897 GL tunnel to inundation risk it never had before
3. spends 2200 tunneling feet straight in the middle of deepest darkest blue
4. piggybacks on top of a high-and-dry oasis of Red Line tunnel around Broadway historically immune to flooding
5. ...thus introducing two flood-immune old subway segments to major risk of inundation for the first time in their history
6. then heads straight for the next-worst dark blue max risk region at Track 61
7. ...and puts a portal smack in the middle of it
8. ...thus ensuring that both old flood-immune subway tunnels intersected face immediate risk of inundation without Netherlands-grade flood protection built everywhere across this new build.

That is not mitigating risk like NSRL is mitigating risk. It goes out of its way to seek risk, then compounds its own risk by risking other structures. Why? Are there ridership counts so stupendously awesome and strategically critical on this routing vs. any other to nullify all these additional risks? Not likely, since the slow backdoor reach around the Seaport has empirically far less demand and far less beneficial congestion mitigation than one that heads for South Station first. What's left that makes this a preferred route over something that seeks less-extreme risks?

Now take a look at the flood map vs. the Transitway connector that was officially proposed for Silver Line Phase III. Essex St.: high-and-dry the whole way. Look in particular at the Atlantic-to-Chinatown Park block of Essex that is the only viable insertion point for a route that hits South Station first: high-and-dry. Hitting South Station first fits the demand pattern and the service goals, which the backdoor route doesn't do. The SS-first insertion point already has a big leg up on flood risk. So why pursue the risk extremes of the demand-inferior backdoor route? Is there any reason at all other than proof-of-concept when service demand isn't it?

Now, we know that Essex on the original SL III plan has many, many other engineering demerits. If flood risk were the be-all of engineering feasibility we'd already have buses rumbling under Essex. But clearly Essex has much more complicated issues weighing it down, and alternative routings have to be studied if they're going to fix what broke SL III. So how about the risks on those South End routings?

• Chinatown Park down Hudson: yellows and oranges, one stretch of magenta, one high-and-dry oasis by the new tower on the corner of Kneeland but also slices perilously close to a dark-blue region. Thoroughly mixed bag, tough to draw firm conclusions. But we knew that; mixed bags and imperfect scoring are all we have to choose from. Any "most-buildable" build is still going to be a very complicated one, and that's why any re-study is going to have to benchmark more than one Alternative across the South End street grid.
• What about Marginal St.? Aha...the frontage roads on the Pike are dry while the NEC/Pike canyon is in a canal! That's a big one: stay the hell out of the canal unless you have no choice but to engage it, like the NSRL's portal or cutover to the Washington St. trolley portal. What about the Marginal vs. Herald sides? The blocks along Marginal are drier by the Washington intersection than the blocks along Herald. Stay on the Marginal side; all things being equal it's safer than Herald, and way way safer than the NEC cut. What about crossing under Orange? It happens under a dry spot, which is good. So now it matters more how long the new tunnel has been running dry before it slips under Orange. Marginal > Herald >>> NEC cut for dry running distance before hitting Orange.

What does this inform us? There's a lot to study here.

• Any Seaport-Downtown connector has to do feasibility scores on a few different build alternatives: Essex, South End, and definitely some sort of "South End Modified" on a different part of the street grid. It tells us that there are no absolutes, and aggregate scoring of SEVERAL alternatives is the only way to make an informed pick. One routing's demerits counted up in a vacuum do not justify another routing's virtues counted up in a vacuum. Head-to-head scoring settles this.
• If flood mitigation were the only consideration, Essex St. would win hands-down...but Essex St. doesn't win hands-down because of its other constraints. So no one risk factor proves all-or-nothing. No build is absolutely precluded by flood risk or narrow street width. But also, no existence of 'a'/any build through a flood zone or narrow streets "opens the proverbial floodgates" to anything-goes map doodles. It's cumulative scoring of all the factors together that sets feasibility.
• Degrees of difference matter. A tunnel inside the NEC cut vs. a tunnel under Herald St. vs. a tunnel under Marginal St. all go the same place for the same service. But a tunnel inside the NEC cut is far riskier than a tunnel under Herald St., and a tunnel under Herald St. is *slightly* riskier than a tunnel under Marginal. That much degree of difference exists on one 2D city block's width. Logically, the only reason to choose a higher degree of difficulty in that compact a region is if the service can't be strung together at all without it (like NSRL having a portal inside the NEC cut). To do the South Bay-via-Track 61 routing you're forced into the NEC cut to avoid the highway structures. Is there anything so compelling about the service demand on a South Bay-via-Track 61 backwards routing to the Seaport that makes plowing through a continuous half-mile of max-risk territory on one particular routing so much better than threading the same service through a half-mile of mixed-risk territory on any number of other routings? And if there is nothing slam-dunk compelling about the service ceiling, why is the build being driven by pursuit of extremes?

 

[Upstruk]

The genesis of this scheme began with working out a portal location for a light rail extension to Dudley Sq. Creating a portal in the Pike / NEC trench seemed like it could be problematic due to the incline slope required to reach the street level above while avoiding the Washington Street and Harrison Ave bridges. Extending the tunnel under Herald street and having a portal under the I-93 viaducts where Herald and Albany Streets are already elevated above the ground under the Viaducts seems like a reasonable solution. Here the line would run under the viaducts and then turn down Traveler St on the way to Washington St. This pitch could end here as a new Green line to Dudley portal location.

The land between Broadway and the Seaport along A, D and E streets is an area likely to be developed once the currently master planned parts of the Seaport are completed. This is a large area and if fully developed will need a transit upgrade. Sending a second branch line off the new Dudley bound portal Via Broadway Red Line would serve this area. It is a bonus that there happens to be an existing trolley tunnel portal directly across Bass River from the new portal. The proposed light rail bridge over the River and rail yard makes this connection possible.

To get from this existing trolley tunnel over to the D Street corridor I figured a 1 to 1 1/2 block tunnel under 4th or 5th Streets to connect to the Bypass Road was reasonable.

In summary this is a scheme to piggy back a second light rail route out of a new Tremont Street tunnel extension to serve Washington Street. This second branch would serve a potential large development area which lacks transit access and then continue into the rest of the Seaport. Now a whole new transit connection is made from the Theater District to the Ink Block, to Broadway, to the D Street corridor and on to the Waterfront.

Another thing I thought was interesting about this pitch is that trains from either the Seaport or Dudley branches could continue north at Park Street to North Station or Loop at Park Street to reach the Back Bay.

Maybe this second branch through the D street corridor is not worth the expense and the required flood mitigation at the Bypass Rd trench, but I thought it was an interesting enough idea to share here.

 

[Shepard]

The genesis of this scheme began with working out a portal location for a light rail extension to Dudley Sq. Creating a portal in the Pike / NEC trench seemed like it could be problematic due to the incline slope required to reach the street level above while avoiding the Washington Street and Harrison Ave bridges. Extending the tunnel under Herald street and having a portal under the I-93 viaducts where Herald and Albany Streets are already elevated above the ground under the Viaducts seems like a reasonable solution. Here the line would run under the viaducts and then turn down Traveler St on the way to Washington St. This pitch could end here as a new Green line to Dudley portal location..

I posted something similar a while ago, suggesting that the I-90 HOV lane that conveniently is on-alignment from Herald Street (and can take transit across all the train spaghetti) be repurposed for the Green Line.

Explanation: http://archboston.com/community/showpost.php?p=247801&postcount=330

 

[Charlie_mta]

I like it. The western end (near Washington St.) could be tied into the E line tunnel for direct back Bay / Seaport service, and also tied into the abandoned Tremont St. tunnel.

 

[Shepard]

I like it. The western end (near Washington St.) could be tied into the E line tunnel for direct back Bay / Seaport service, and also tied into the abandoned Tremont St. tunnel.

Not sure if you're referring to Upstruck's proposal or my HOV lane idea, but in both cases yes - the idea is a routing from the Tremont Street Tunnel and/or Back Bay connection via an E extension. Most of the posts in the Green Line Reconfiguration thread try to do something similar, but send the GL to South Station first from the Herald/Pike alignment (in various ways that prove either complicated or contentious).

Personally, I like the idea of re-purposing the HOV lane. When I first proposed it, the discussion quickly veered into debating the merits of HOV lanes. Whatever the case there is, this Airport HOV tunnel is hands-down an underutilized piece of expensive infrastructure which would get 1000x more use as a transit tunnel - and the fact that it's straight on alignment from what could be a box tunnel under Herald is a great coincidence.

 

[F-Line to Dudley]

Not sure if you're referring to Upstruck's proposal or my HOV lane idea, but in both cases yes - the idea is a routing from the Tremont Street Tunnel and/or Back Bay connection via an E extension. Most of the posts in the Green Line Reconfiguration thread try to do something similar, but send the GL to South Station first from the Herald/Pike alignment (in various ways that prove either complicated or contentious).

Personally, I like the idea of re-purposing the HOV lane. When I first proposed it, the discussion quickly veered into debating the merits of HOV lanes. Whatever the case there is, this Airport HOV tunnel is hands-down an underutilized piece of expensive infrastructure which would get 1000x more use as a transit tunnel - and the fact that it's straight on alignment from what could be a box tunnel under Herald is a great coincidence.

Yeah...believe that inquiry left off with affirmative confirmation that the dimensions would work for transit use before discussion got sidetracked.

The only real problem with the HOV re-use is the demand question. Downtown direct to Seaport bypassing South Station or hitting it dead-last whiffs on all the Red Line congestion mitigation that's the crux of the Seaport's mobility problems. Yes, it's theoretically easier and less-costly in absolute terms to string up, but Park St. to Silver Line Way one-seat isn't the burning mobility question begging to be answered: it's the SS+DTX and SS+Park transfer dances. As long as the two-step from the South Station Red Line platform remains faster and more frequent than a meandering 5-7 stop loop-around, it's not going to meaningfully address the mobility barrier that's choking off downtown circulation.

So it's a little spurious to pitch the backdoor route as "oh, it's a down payment on a future perma-fix with +1 utility." No, it really isn't. It doesn't pose remotely the same question-and-answer as Silver Line Phase III. Or SL-Washington, for that matter. Spending there first puts addressing the real problem further than ever from goal, and thus makes it a 'bad' transit allocation. 'Bad' use of public works resources can be a whole lot less expensive than 'good', but losing sight of the demand question in the target-fixation chase for routing or modal force-fits is exactly how the Silver Line shipwrecked itself. "Backdoor to Seaport and address the SS double-transfer dance later" is some other era's "shotgun-mode Washington St. replacement service with the Transitway, and figure out how to mash them together later." It seems plausible on-paper until you get the sinking realization years later that the answer doesn't go anywhere near the burning question, and that a whole lot of missplaced focus set back the goal. If there's any project that can ill-afford to make that same mistake, it's this one...failing to answer the same question the last attempt didn't.



In reality, Transitway backdoors are much more appropriate for addressing Urban Ring demand re: stringing together the SE quadrant of the route pattern. Mainline transit that reaches SS inbound from the Seaport is exactly how that radial build is going to do it, and the defining difference in how the Silver Line and Urban Ring differentiated themselves on the BRT mode. You could have something tasty cooking with the HOV lanes when benchmarking possible UR routings between Dudley and the Seaport for the UR. A lot of the UR possibilities target the Haul Road, but Haul Road is awkwardly placed halfway between Broadway and Andrew so the backtrack to/from your pick-'em Red/Dorchester transfer requires unsatisfactory amounts of street-running and turning movements. Puts a problematic toilet clog in the middle of the route that un-does most of the travel time + frequency benefits of the Melnea Cass reservation and Transitway/Haul Rd. on each side of the clog. It would be very interesting indeed if the HOV's proximity to Broadway sharply curtailed the amount of time the UR had to burn in mixed traffic and could feasibly make most of the Dudley-Transitway trunk reservation- or lane-separated.

And, if you are hellbent on getting trolleys and not BRT on the street-heavy south half of the UR, how much you can minimize the mixed-traffic running between Melnea Cass, that Red transfer, and final trajectory into SL Way may be the make-or-break decision on whether the traffic separation can be good enough to hack it on LRT. I could most definitely see the HOV lanes playing into that equation. Helps even more that swinging onto the HOV onramp out of Broadway takes you only 2 blocks away from Washington St. at point of insertion. You could have a 2-block set of non-revenue tracks down Herald between the Washington and Albany intersections acting as a Chestnut Hill Ave.-esque equipment pipe, service disruption diversion, or negligible-risk canvas to doodle around with minor alt service patterns (GC Loop to unidirectional Seaport super-loop-da-loop?).

^^That^^ I think is asking a demand question that the HOV's can directly answer head-on. Just beware the temptation to lump it in with the SL Phase III replacement because the backdoor looks construction-cheaper and in the same neighborhood. It's not a down payment or compromise solution when the "cheaper" route sidesteps the majority-share of the demand question; it means the cost/benefit comparison is faulty.

 

[Shepard]

Yeah...believe that inquiry left off with affirmative confirmation that the dimensions would work for transit use before discussion got sidetracked.

Right - I frankly have no idea how to find the tunnel's dimensions, so I suppose it's quite theoretical until that info comes to light.

The only real problem with the HOV re-use is the demand question. Downtown direct to Seaport bypassing South Station or hitting it dead-last whiffs on all the Red Line congestion mitigation that's the crux of the Seaport's mobility problems. Yes, it's theoretically easier and less-costly in absolute terms to string up, but Park St. to Silver Line Way one-seat isn't the burning mobility question begging to be answered: it's the SS+DTX and SS+Park transfer dances. As long as the two-step from the South Station Red Line platform remains faster and more frequent than a meandering 5-7 stop loop-around, it's not going to meaningfully address the mobility barrier that's choking off downtown circulation.

I've said before that the best "straight line OCD" route - theoretically - would be Boylston to South Station via Essex. No doubt.

But let's also recognize that the HOV routing does in fact free up some capacity at the Park/DTX/SS choke points:

1) North Station to Seaport - nobody will need to transfer to the Red Line.
2) BBY to Seaport - if your end destination is significantly past South Station, you will more likely transfer at Tufts Medical to the GL into the HOV tunnel.
3) Copley to Seaport - if there's a E-line connector, it's a no-brainer that nearly 100% of Seaport-bound traffic would take the one-seat ride and avoid connections. Even without it, a significant amount would connect at Boylston (via moving to the southbound platform into the Tremont St Tunnel)

 

[F-Line to Dudley]

Right - I frankly have no idea how to find the tunnel's dimensions, so I suppose it's quite theoretical until that info comes to light.

16 ft., Interstate-spec. If it's ever any less, FHA regs require putting a height measurement warning sign. None of the CA/T portals have restricted-height warnings like the Sumner and Callahan do, so it's all good. And if it weren't, several layers of pavement would get torn out by default if you're having a dedicated rail ROW with normal rock ballasted railbed instead of street-running rail. Rail tunnels don't need anywhere near the multi-foot layering of pavement and reinforcement on the floor that a road tunnel does.

The single-lane EB tunnel is plenty wide enough for 2 trolley tracks if you cannibalize the catwalks on either wall, which are unnecessary for LRT. It's got decent-size shoulders on it in addition to the catwalks. Since the other bore is 2-lane you still have unused tunnel capacity to spare for other purposes.

I've said before that the best "straight line OCD" route - theoretically - would be Boylston to South Station via Essex. No doubt.

But let's also recognize that the HOV routing does in fact free up some capacity at the Park/DTX/SS choke points:

1) North Station to Seaport - nobody will need to transfer to the Red Line.
2) BBY to Seaport - if your end destination is significantly past South Station, you will more likely transfer at Tufts Medical to the GL into the HOV tunnel.
3) Copley to Seaport - if there's a E-line connector, it's a no-brainer that nearly 100% of Seaport-bound traffic would take the one-seat ride and avoid connections. Even without it, a significant amount would connect at Boylston (via moving to the southbound platform into the Tremont St Tunnel)

This is where I strongly disagree. A direct connection from Boylston to SS gets you from North Station to South Station in 6 stops. At most 7 if it's a Marginal St. wrap-around with Ink Block infill. And every single one of those stops except Ink features an inter-line transfer, with 10,000+ riders at all except Ink because of the transfer utility. The backdoor route, on assumption that you're not just running express from Tufts to SL Way, is anywhere from 10-12 stops, same as Brookline Hills to North Station. With a huge ridership crater at the string of intermediates between Tufts transfer and SS transfer. The longest SL III replacement routing through the South End is ~2-1/3 track miles from North Station...approximately the distance from North Station to Hynes. This backdoor route is 2 miles longer, the equivalent of North Station-Brookline Village (that Brookline Hills comparison is not far off at all). At such longer distance with many more stops the headways are going to be more diffuse. And the overlap with longest-distance SL1 arrivals and longest-distance trolley arrivals at the portal is far more variable for dispatch to time vs. trolleys that start intermixing when the Silver Line is at end-of-run looping, or vice versa at SL Way where trolleys are end-of-run looping. The variability is going to require more spacing of trolley vs. SL1 headways for bunching/conflict prevention, further reducing the service density on this backdoor route. It's going to be more like the C or E than "halfway-to-mainline" service levels. Better than today's Silver, but not nearly dense enough for the primary demand of load-spreading Red around downtown.


That's an order of magnitude poorer travel time and frequency from being faster than the double-transfer dance at SS+DTX and SS+Park. A majority of riders needing to bounce around downtown are going to keep doing what they're doing, and Red won't improve. The load relief comes from a niche audience at the mid-line intermediate stops, who will no doubt appreciate this. But it doesn't do meaningful enough work for the prime downtown circulator demand seeking immediate direct access to that murderer's row of transfers. That overcrowding and dwell time decay on Red is not going to reverse itself, and any reduction in headcount is going to be inconclusive and short-lived compared to taking the direct routing.

It's not asking the same demand question. That's why it's spurious logic to pitch this as meaningful partial answer. It is closer in actuality to the big misjudgement that the Silver Line made to justify its modal choice: that Dudley Sq. to Seaport via Downtown was somehow a service pattern that beckoned a build because it just so happened to look like a stately color line on the map. It wasn't; it was a niche nice-to-have for a handful of people while the two halves of the line kept wholly separate demand audiences that rarely intermixed. The ridership overturn at Boylston projected to be near-total, with Seaport-Downtown the orders of magnitude bigger half than Washington. It necessitated that performance-killing mid-line loop because the niche demand wasn't compatible with the primary demand and apportionment of headways didn't work with the asymmetry.

As I said, that's an excellent path for the Urban Ring where the radial circulator links neighborhoods and outer transfers first, downtown last. But blurring the lines between SL III's downtown ground-zero demand and the UR's radial demand by shotgunning partial pieces together out of engineering expedience makes the same error in judgment that the Silver Line did conjoining Washington with the Transitway out of engineering expedience. If not quite as badly, then at least a lower-case version of history repeating itself with the same logical error. It's poor allocation of resources resulting in bad(-er) transit to start with a leading answer that has to kludge together fringes of the demand question for self-justification. That's not useful here. There is a screaming-obvious demand question being asked of SL III and its alternatives: move those hoardes out of South Station and distribute them immediately to the transfer points so Red and the DTX + Park congestion on the Red platforms can save itself, and in turn uncap Seaport mobility BOTH on the one-seat circulator AND on Red. Full-stop...nothing else matters unless the build engages that head-on. Taking a swing from Seaport intermediates through Broadway at the triple-junction of residential Southie, Dorchester, and the South End is the job of the Urban Ring: radial, neighborhood-to-neighborhood, transfers outside the CBD. Blurring the lines isn't clarity; it makes for muddled solutions that don't do their job nearly as well as hoped. We deal with that frustrating gap every day on Silver; we'll be dealing with it on the backdoor meander when headcounts on those overstuffed downtown Red platforms don't inch down enough to matter.

 

[Shepard]

We're disagreeing because you're focused on South Station, whereas I am focused on the seaport.

If you're commuting on the GL from the Back Bay or any western GL branch, and you're going to the Seaport - but not South Station - you will transfer at Boylston onto the Tremont Street Tunnel service. And, if there's a E-line connector, you may not even need to transfer. In any case, you will not ride the extra station to Park, switch to RL, then switch to SL/GL anymore. If we're talking about the Seaport, not South Station, those extra transfers become inane. Pressure off the Red Line.

If you're commuting on the OL from Forest Hills or Back Bay Station, and you're going to the Seaport - but not South Station - you will transfer at Tufts Medical to the new service. You will not stay on to switch to the RL at DTX and then switch to SL/GL. Pressure off the Red Line.

Apologies for the bad schematic