Green Line Derailments Increasing

[Bramdeisroberts]

Could any/all of this be avoided by going with any of the half dozen-odd all low-floor trolley designs that can be more or less ordered "off the shelf" from any of the major manufacturers these days?

It seems as if the all-truck designs like the Type-7 or the Boeing LRV's work fine, while the all-stub axle designs like the modern 100% low floor trams also behave well on sub-par rails. Mongrels like the Type-8 that mix heavy driven bogies fore and aft with a lightweight unpowered stub axle center bogie seem doomed to fail from the start, especially with the drawbar-based center pivot design that the low floor necessitates that will inevitably place far more sideways loads on the bogie than the turntable design on the high floor trolleys ever did.

It'll be "interesting" to see how CAF USA's spectacular dysfunctionality plays out with regards to the engineering and build quality of the '9s. We may all end up with lemons that make the 8's look like the Kinki's, and all because the T is afraid to do a 100% fleet replacement order of off-the-shelf Flexity or Citadis hardware.

[CRail]

Could any/all of this be avoided by going with today's off the shelf designs? Probably. The type 8s were designed when low floor was a pretty new thing. Their expected delivery date was only 6 years after the ADA was signed into law. The concept has been greatly improved.

I wouldn't call CAF dysfunctional and recommend Flexitys in the same paragraph. Because of Bombardier's follies, the days are no longer numbered for a fleet that's supposed to be extinct already.

[The EGE]

Green Line has a lot of non-standard features, many of which are a result of the system being built so early. Some of them (clearance issues especially) can be potentially rebuilt; some like the Park Street loop's tight radius are probably baked in forever. Two of the tricky parts - Lechmere Loop, and the 3D S-curve coming off the viaduct - will go away with GLX.

Tremont Street Subway was opened 1897-1898, Lechmere Viaduct opened 1912, and Boylston Street Subway opened 1914. Philadelphia had an additional decade after the TSS to figure out their straight-line trolley subway, by which time trolley tech and engineering was much more advanced. SF didn't open their first tunnel till 1917, and Newark till 1935. So it's no wonder they're able to use more off-the-shelf equipment; their tunnels were designed with a much wider knowledge base.

[F-line to Dudley via Park]

The only thing dysfunctional about CAF is their tarnished rep for punctuality. The product they deliver tends to be uniformly top-notch quality. Even with that Amtrak clownshow the Viewliner baggage cars have gone through their teething process without hiccups and have gotten positive marks from Amtrak employees on build quality and attention to detail. Same can be said of a lot of their self-powered product in both the mainline rail, HRT, and LRT markets. They're just habitually slooooooooowwww at delivery.

But that's going to mean different things to each customer. It's making AMTK very angry right now because those late ViewFood diners have forced them to pull the shot Heritage diners from the lineup and replace them with tarted-up dinette coaches that can only do microwaved food. A customer service nightmare. Coming on the heels of Nippon-Sharyo's big belly-flop with the bi-level order. It handcuffs AMTK's ability to juggle other procurements that have to be queued up now to still have to be dealing with testing on an order that CAF should've completed a long time ago. It's not likely to matter as much if they're tardy on next year's Type 9 pilot. Which is first and foremost an expansion, not replacement, order. The T is distracted by so many other crises at the moment, including new backlash this week from media reporting on their unfilled staff positions and unfilled hiring manager positions who are supposed to be filling all the front-line vacancies. They don't have a lot of bandwidth to juggle a lot of balls in the air, so if the 9's are a little tardy...well, as long as they're quality product that don't make a mess of themselves during testing quality is going to be well worth waiting for (within reason).


The only thing that worries me a little about the current fleet plan (or at least the one presented to the FCMB 10 months ago long before this derailment flare-up) is them wanting to go back to the drawing board after the 9's with a Type 10 order that aims for as much low-floor surface area as you can possibly cram inside a trolley designed for Boston. Why are they trying to attempt bang-bang redesigns unless they still have concerns about resiliency of the center trucks on any half-and-half make (in which case...why are they taking another risk on a purely expansion order instead of getting it right?). That doesn't seem like a good idea to have 24-54 brand new expansion cars that become immediate oddballs before they're 5 years old because 200+ replacements have a different--and theoretically superior--layout. They don't exactly have the luxury of time to take the extra years for a new redesign that chews up 5 years on the clock when the billion-plus in funding for those 200+ replacements has yet to land on the 4-year CIP (which now covers FY2021).

The Bredas really, really are going to be in tough shape if they have to get band-aided through 2025-27 because they're taking the hit on another full redesign. If the Type 9's work well, the Breda truck design glitch is completely fixed (which shouldn't be a reach), and they're 100% ADA compliant as half-and-halves...Keep It Simple Stupid™ and just immediately plunk down for 200 more copies after these 54 expansion cars are delivered. Their unit costs for a large order of fully-debugged 9's are going to be very attractive at 200-car ordering scale, and they'll get delivered much faster from a CAF assembly line that doesn't need any retrofitting to keep churning. That's exactly the logic the FCMB is using for expanding out the Red Line replacements with a follow-on that replaces, rather than rehabs, the 01800's while the CRRC assembly line is hot. Not to mention one entire 250+ unified Green Line roster of nothing but Type 9's greatly simplifies what components the shops have to maintain for the following 25 years.

It's early yet, but that fleet strategy could use some scrutiny and revision given the agency's past pratfalls with overcustomization and current conditions rapidly changing odds of being able to stretch the current roster through another new-design gestation period.

[BandA]

What if they replace the center section with a center car, so that there are 3 segments? Or they spit the cars in two and put in two axles and a coupler? Then it's just a fare collection problem, solvable with proof-of-payment.

[BostonUrbEx]

the Park Street loop's tight radius are probably baked in forever

Couldn't they eliminate the loop if they had universal crossovers south of the Park St platforms? Not sure exactly how complicated that actually is as far as support columns and signaling.

[Disney Guy]

"Replace the center section with a car"
Do we really want to go back to non-articulated (probably 45') vehicles.

"Eliminate the Park St. loop and install universal crossovers south of the station"
Would be confusing to passengers unless the boarding location, including any on the "inbound" side, for each destination was the same for all hours and all days and all trips. Also an operational nightmare if you have occasional "wrong way" pull ins and pull outs for cars terminating at Park St. (tracks 2 and 3) mixed with through service.

[Bramdeisroberts]

"Replace the center section with a car"
Do we really want to go back to non-articulated (probably 45') vehicles.

I think he meant more along the lines of the Dallas SLRV's
https://upload.wikimedia.org/wikipedia/ ... 015_10.jpg" onclick="window.open(this.href);return false;
Where you would end up with an individual unit that was ~50% longer than a Type 7 or Type 8 by adding a 3rd articulated segment in the middle. It might work, but it might also add another derailment-prone lightweight stub axle bogie to each trainset.

Personally, I think that the T needs to think big with the Green Line, especially if there isn't going to be an Indigo-ized Worcester Line, preferably with a Yawkey-Kenmore connection, to help de-stress the central subway. I'd love to see them follow LA, MUNI', and the DLR's lead and aim for all high-platform service to REALLY expedite station dwell times, and that would sync perfectly with a 100% fleet replacement order and signalling upgrade that could be made around 2025-2030 or so. Hell, it might even be an opportunity to scrap the turnaround loops wherever possible and switch to a larger/faster LRV design to transform the Green Line into the light rapid transit line that it's passenger volumes actually warrant.

It's a pipe dream, for sure, but there's so much deferred maintenance on the GL as it is, that it might just be worth it to pony up the extra cash for a massive upgrade to allow it to push Docklands Light Rail-level service speeds and passenger volumes.

[typesix]

The PCC car was primarily made as a single ended car because the designers wanted to speed up service by using loops. Loops are generally faster than having to change ends, especially with today's modern vehicles that have to boot up.

[MBTA3247]

"Replace the center section with a car"
Do we really want to go back to non-articulated (probably 45') vehicles.

I think he meant more along the lines of the Dallas SLRV's
https://upload.wikimedia.org/wikipedia/ ... 015_10.jpg" onclick="window.open(this.href);return false;
Where you would end up with an individual unit that was ~50% longer than a Type 7 or Type 8 by adding a 3rd articulated segment in the middle. It might work, but it might also add another derailment-prone lightweight stub axle bogie to each trainset.

No, it wouldn't. Only the middle of the center section on the Dallas cars is low-floor; everything else is high-level, with normal trucks all around. Kinki Sharyo originally built those cars as two-section cars, same as the Type 7s. The center sections were designed to be drop-in additions, simultaneously increasing DART's capacity and providing ADA compliance without the expense of all new cars.

[F-line to Dudley via Park]

"Eliminate the Park St. loop and install universal crossovers south of the station"
Would be confusing to passengers unless the boarding location, including any on the "inbound" side, for each destination was the same for all hours and all days and all trips. Also an operational nightmare if you have occasional "wrong way" pull ins and pull outs for cars terminating at Park St. (tracks 2 and 3) mixed with through service.

Actually, he's referring to a $12M fed grant award the T got about 7 years ago to install crossovers from the inbound loop side to the outbound track to facilitate thru service on the inner track. That would've allowed North Station and Lechmere trains to get waved ahead of all GC-turning trains from Park to their platform spot on the far end of the GC platform, eliminating bunching and increasing total capacity on that congested stretch. The work would've involved relocating a couple support beams and electrical boxes, then installing a crossover. It would not have eliminated the loop, since the crossover would've forked off before the loop. Loop's still needed for giving the early hook to schedules running so late they've already screwed up dispatching.

Grant was canceled and returned to the feds when the engineering assessment on moving the support beams estimated it would cost over twice as much as initially anticipated. Determination was that it was a nice-to-have, but not anything required for handling GLX traffic because signal priority on B/C/E would do more to attack the bunching problem at the source. It is always something they can revisit later when they need it because true cost has now been pegged. Would be very useful to have if the Green Line moves to primarily 3-car trains during all peak periods, where triplets can't back-to-back at the Park inbound platform like deuces can. But there'll never be good enough reason to give up the throttling ability of the loop for yanking blown schedules, so that's always going to be a ruling curve for car design even if the inner track gains thru-running capability.

[highgreen215]

No, it wouldn't. Only the middle of the center section on the Dallas cars is low-floor; everything else is high-level, with normal trucks all around. Kinki Sharyo originally built those cars as two-section cars, same as the Type 7s. The center sections were designed to be drop-in additions, simultaneously increasing DART's capacity and providing ADA compliance without the expense of all new cars.[/quote]

A modern Two Rooms and a Bath design? Why not?

[BandA]

I was thinking of a center section and continuing to articulate. The center section could be non-ada since the rest of the vehicle provides that. By making the center section about the same length as the front or back, I think it would be less likely to "jackknife". Of course, who would design, manufacture or test such a modification would be problematic. But it would be the solution the BERy would choose!

[Bramdeisroberts]

"Replace the center section with a car"
Do we really want to go back to non-articulated (probably 45') vehicles.

I think he meant more along the lines of the Dallas SLRV's
https://upload.wikimedia.org/wikipedia/ ... 015_10.jpg" onclick="window.open(this.href);return false;
Where you would end up with an individual unit that was ~50% longer than a Type 7 or Type 8 by adding a 3rd articulated segment in the middle. It might work, but it might also add another derailment-prone lightweight stub axle bogie to each trainset.

No, it wouldn't. Only the middle of the center section on the Dallas cars is low-floor; everything else is high-level, with normal trucks all around. Kinki Sharyo originally built those cars as two-section cars, same as the Type 7s. The center sections were designed to be drop-in additions, simultaneously increasing DART's capacity and providing ADA compliance without the expense of all new cars.

I was responding to someone's suggestion that they do a similar conversion to the 8's and 9's, though I'm honestly shocked (not really) that the T never considered a similar upgrade to the 7's

[Bramdeisroberts]

I was thinking of a center section and continuing to articulate. The center section could be non-ada since the rest of the vehicle provides that. By making the center section about the same length as the front or back, I think it would be less likely to "jackknife". Of course, who would design, manufacture or test such a modification would be problematic. But it would be the solution the BERy would choose!

If you REALLY wanted to start smoking the ganj, you could tear a page from the APT and go with a high-floor powered center section with low-floor non-powered articulated section on either end. Sort of an "inside-out Type 8"...