Acela Replacement and Disposition Discussion

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Re: Acela Replacement and Disposition Discussion

Postby gokeefe » Sat Oct 07, 2017 8:53 pm

AC4619 wrote:I don't see, barring a specific FRA reg, why we wouldn't be able to expect 8%. Acela cars were built a bit too wide to fully tilt on certain parts of the RR, and even then, wouldn't tilt that much. I sincerely hope (and expect) that is not a repeated mistake. If Alstom claims 30% faster speeds, they're the ones designing the train, and presumably have studied the NEC quite extensively, so they probably know what they're talking about. Now, in marketing, you can manipulate numbers all sorts of ways to make your product sound good: "The Acela travels at up to 150 mph!" [fine print: for 20 miles after going amazingly slow for a couple hours]. In this case Alstom didn't provide context: what curves, can handle 30% more speed? I'm sure some curves will be able to, but, it depends on curve radius & superelevation amongst other things, as I'm sure you know better than me. Point is...no reason to believe either 8% or 30% are false numbers, just, as is typical in marketing, lacking the scenarios used to come up with them. Not to say you were implying you didn't believe the numbers either, by the way.


The issue would be spacing of track centers through curves and whether or not there is enough room for the trainsets to safely tilt at 8%. I hope that they can in service on Amtrak but I don't know it. Same goes for % speed increases.

AC4619 wrote:One would think, yes, based on the CGI renderings provided by Alstom & the promotional videos posted by Amtrak, which show the locos tilting with the rest of the train on curves, and even show an overhead view with the pant tilting on a hinge as the loco tilts. It could be passive tilt, it could be marketing, but, it'd be weird to make simulation videos that don't depict what you actually expect your product to do. Granted, I too have yet to see an official report stating unequivocally, that the locos have active tilt.


I actually think its implied pretty strongly because of the shared trucks ("bogies") between passenger cars and power cars. Not to mention that this is probably standard practice for Pendolinos in service everywhere else in the world. There is also no question that the tilt technology is active ("anticipatory") and not passive. That is stated directly in the spec sheet (and most other materials with any detail at all).
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Re: Acela Replacement and Disposition Discussion

Postby electricron » Sat Oct 07, 2017 9:41 pm

gokeefe wrote:I actually think its implied pretty strongly because of the shared trucks ("bogies") between passenger cars and power cars. Not to mention that this is probably standard practice for Pendolinos in service everywhere else in the world. There is also no question that the tilt technology is active ("anticipatory") and not passive. That is stated directly in the spec sheet (and most other materials with any detail at all).

From the drawings I’ve spied, the power cars are not sharing bogies/trucks with the coach cars. The coach cars are sharing bogies/trucks with each other, but not with the power cars. I believe reducing the weight over axels is the reason why. Which is also why the individual coach cars will not be as long as the Acela coach cars.
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Re: Acela Replacement and Disposition Discussion

Postby OrangeGrove » Sat Oct 07, 2017 9:51 pm

gokeefe wrote:I actually think its implied pretty strongly because of the shared trucks ("bogies") between passenger cars and power cars.


The initial promotional video appears to show separate trucks for the locomotives; Only the passenger cars are articulated. However, it specifically refers to an active-tilt system.
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Re: Acela Replacement and Disposition Discussion

Postby BandA » Sat Oct 07, 2017 11:08 pm

What happens if the tilt mechanism fails on one car as it's going into a curve?
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Re: Acela Replacement and Disposition Discussion

Postby amtrakhogger » Sun Oct 08, 2017 7:27 am

BandA wrote:What happens if the tilt mechanism fails on one car as it's going into a curve?


The car automatically centers and the speed must be reduced.
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Re: Acela Replacement and Disposition Discussion

Postby Matt Johnson » Sun Oct 08, 2017 11:12 am

electricron wrote:From the drawings I’ve spied, the power cars are not sharing bogies/trucks with the coach cars. The coach cars are sharing bogies/trucks with each other, but not with the power cars. I believe reducing the weight over axels is the reason why. Which is also why the individual coach cars will not be as long as the Acela coach cars.


Correct, standard TGV configuration. I think this is may be the first time that articulation is combined with active tilt though. I assume each coach will need its own tilt mechanism connected to its half of the shared truck. I am curious to see whether the locomotives feature active tilt as well. My guess based on the revised/refined rendering is that maybe it was deleted to save weight and/or reduce complexity. I'll also be curious to know the locomotive weight. If I recall correctly, the Acela locomotives/power cars weigh in at 102 tons, while a TGV loco is just north of 80 tons.
Last edited by Matt Johnson on Sun Oct 08, 2017 5:32 pm, edited 1 time in total.
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Re: Acela Replacement and Disposition Discussion

Postby gokeefe » Sun Oct 08, 2017 12:11 pm

Matt Johnson wrote:Correct, standard TGV configuration. I think this is may be the first time that articulation is combined with active tilt though.


The pairing of articulation with tilt definitely seems to be a major innovation and I'm a impressed that both Alstom and Amtrak are going to do it. It's interesting to see U.S. high speed service being at the global forefront of technology.
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Re: Acela Replacement and Disposition Discussion

Postby east point » Sun Oct 08, 2017 6:29 pm

Track spacing both on straightways and curves may depend on tilt and non tilt both going same way and opposite. Two 160 MPH Acelas meeting each other at 320 relative closing velocity is a cause of much testing. Add in a 4 track configuration of the NEC with trains of various types on all 4 tracks crossing same point at a moment in time ????. That is an occurrence very seldom elsewhere in the world at those speeds ?
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Re: Acela Replacement and Disposition Discussion

Postby BandA » Sun Oct 08, 2017 10:21 pm

PTC would need to know where tilting is not allowed, where tilting is restricted. So on some curves the active tilting might have to be tuned down, while on other curves you get to go "Full Tilt"
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Re: Acela Replacement and Disposition Discussion

Postby Matt Johnson » Wed Oct 11, 2017 8:51 am

Looking at the pantograph housing, I'm pretty convinced that they deleted active tilt from the locomotive/power car.

http://www.railwaygazette.com/news/sing ... erway.html
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Re: Acela Replacement and Disposition Discussion

Postby Greg Moore » Wed Oct 11, 2017 10:56 am

Matt Johnson wrote:Looking at the pantograph housing, I'm pretty convinced that they deleted active tilt from the locomotive/power car.

http://www.railwaygazette.com/news/sing ... erway.html

My understanding is that active-tilt is more for customer comfort than anything else?
So engineers can just brace more going into the curve.
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Re: Acela Replacement and Disposition Discussion

Postby gokeefe » Wed Oct 11, 2017 11:10 am

I think its tough to read too far into a model like that which might have altered the height of the pantograph mounting bracket. However, I do agree that the model is clearly supposed to be a highly accurate scale representation.

Its interesting if you compare to the original video and via online search that there appears to have been a change. Worth noting ... what's on the model appears very similar to the type of equipment used on Pendolino trainsets operated by Virgin in Britain.
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Re: Acela Replacement and Disposition Discussion

Postby Matt Johnson » Wed Oct 11, 2017 11:34 am

Greg Moore wrote:My understanding is that active-tilt is more for customer comfort than anything else?
So engineers can just brace more going into the curve.


Correct, and yeah, that's what I'm thinking.

On another note, I'll be curious to see if the 20 Acela sets see any sort of second life. There has to be some value to the 40 locomotives and 120 coaches that are less than half the age of the workhorse Amfleets one would think. That's a lot of young rolling stock to just throw away, but then I suppose the unique maintenance requirements and also the lack of low level traps are limiting factors for any second act. But maybe some less stressful use of the coaches, sans active tilt, like running behind steam locomotives on some tourist/excursion operation? :)
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Re: Acela Replacement and Disposition Discussion

Postby electricron » Wed Oct 11, 2017 11:46 am

Matt Johnson wrote:
Greg Moore wrote:My understanding is that active-tilt is more for customer comfort than anything else?
So engineers can just brace more going into the curve.


Correct, and yeah, that's what I'm thinking.

On another note, I'll be curious to see if the 20 Acela sets see any sort of second life. There has to be some value to the 40 locomotives and 120 coaches that are less than half the age of the workhorse Amfleets one would think. That's a lot of young rolling stock to just throw away, but then I suppose the unique maintenance requirements and also the lack of low level traps are limiting factors for any second act. But maybe some less stressful use of the coaches, sans active tilt, like running behind steam locomotives on some tourist/excursion operation? :)


How much does the lack of traps complicate their reuse elsewhere? How difficult would it be to add traps onto them?
These 120 railcars, if traps were added, could be used by VIA on their main Montreal to Toronto corridor. Bombardier could bring out their turbine power locomotive power units, or use diesels instead for the prime mover. It’s not like Bombardier hadn’t done so in the last - because they have. VIA is presently desiring new corridor rolling stock to replace their LRCs, and these could fit in nicely if the trap problems could be fixed.
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Re: Acela Replacement and Disposition Discussion

Postby Matt Johnson » Wed Oct 11, 2017 11:58 am

electricron wrote:VIA is presently desiring new corridor rolling stock to replace their LRCs, and these could fit in nicely if the trap problems could be fixed.


Apparently VIA has 72 LRC coach cars and 26 LRC club cars in the fleet. So, the 120 Acela coaches wouldn't be an unreasonable number for a replacement fleet. VIA seems not to have interest in active tilt, having removed tilt from the LRC fleet. And the Acela coaches are designed to be operated as fixed sets. I don't know how feasible it might be to convert them for conventional use, but it does seem like a long shot.
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