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zephyr17

Amtrak's single level midriff bulge. Why?

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I was thinking about Anderson's stated preference for a standard, single level LD fleet in the future, and I was stuck by the design of Amfleets and Viewliners, which both bulge in the middle. Why?

 

I guess a case can be made that the somewhat tubular shape of the Amfleets (direct descendant of the Metroliners) could be for structural strength. But the Viewliners are not tubular, they are two flat surfaces that meet at an angle and I can't imagine it does anything but complicate the structure.

 

No clearance plate is wider in the middle than the top or bottom, past the first 3' 4" above the railhead and then a short taper at the top. All the plates, even the restrictive Plate B (unrestricted interchange) allows for a 10' 8" width from there to 13' 9" above the railhead. So why the bulge? Why not just take advantage of the entire 10' 8" width straight sided.

 

The Superliners don't buldge, the Acelas don't bulge, the railroads' own passenger fleets never had the bulge. So what is the purpose?

Edited by zephyr17

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The Budd Metroliner was the basis for the Amfleet, and since the Metroliners were supposed to compete with the airlines, and the world was experiencing a bit of an obsession with air travel, they wanted the Metroliners to have the appearance and style of an airplane. Hence the small windows and round body (though the tiny windows were also chosen because people tended to throw rocks at them back then).

 

Viewliners I'm not sure about.

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the Acelas don't bulge

 

They do bulge. :huh:

Edited by cpotisch

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Actually the Superliners do, in a sense. They angle out at the bottom coming out to their full width about 1/3 the way up the door. The Acela bulge even more, it's more akin to the Viewliner bulge however you can see it here: http://photobucket.com/gallery/http://s248.photobucket.com/user/phoebevet/media/railfan/amtrak10003.jpg.html

 

Thinking about it, the only equipment that doesn't would be the Horizons & any remaining Heritage equipment.Even the Talgos bulge (but to a much less degree), I noticed (looking for that Acela pic) that the new Acela II is currently planned to have a bulge & I just looked at the planned Midwest cars and they to have a bulge (although it's more like the Superliner's)

 

peter

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You can distinctly see how the Birghtline cars bulge but the engines don't:

 

newsEngin.18504208_012017-Brghtline-test

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Yeah, I guess Acela's do bulge but relatively subtly. I was really thinking about the large, very obvious bulges in the Amfleets and Viewliners. And why?

Edited by zephyr17

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I feel like the term bulge is pretty broad. If you just take it to mean anything without completely straight sides, then pretty much every carbohydrates can described as bulging. If you take it to mean a car that has a point along the side where its at its widest, then a Superliner wouldnt count, since most of the car is the same width. Even so, that would mean that any curved train car is by definition bulging, which still might be a little broad. My point is, Im not sure if there is any real way to say that one type of train car does bulge, and another type does not.

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I am really interested .the pretty dramatic width change like in the Viewliners and Amfleets, not a subtly curved side (apparently really subtle in the case of Superliners they always looked straight to me past the flare on the bottom, which is demanded by clearance plates). I really was wondering why the reason for a change of several inches in the car width. I can accept that Pennsy and DOT wanted something that echoed airliners in the 1960s for the Metroliners that resulted in the tubular shape of the them and their descendents, the Amfleets, so that was largely aesthetic, although I can see the curved side could add strength.

 

I don't particularly want to get in a "rivet counting" kind of discussion of how to define bulge.

 

So I will narrow the question. Why do the Viewliners have their very large bulge. Structurally it doesn't make sense to me, and there is no clearance reason for it.

Edited by zephyr17

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There is an article in the current Trains magazine that answers this question. I don’t recall exactly what the reason was, so I won’t try to guess at it here.

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It's pretty straightforward: the cars are as wide as they can be at 48" above the rail so they can nestle up to a high-level platform. If you want more room at armrest height, you can bulge out the shell so you can have wider seats/roomettes.

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As I get older and fatter, every car I ride bulges when I get on!

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Okay, on all the clearance plates, width reaches its maximum (10' 8") at 3' 4" above the rail head, and remains at maximum pretty much to where it curves in at the very top. So it is the same maximum width at 3' 4" above the railhead as it is 8 inches higher at 4'. They don't get any wider than 10' 8" no matter how high you go. So "as wide as they can be at 48 inches above the rail then bulging out" makes no sense unless the high level platforms don't conform to AAR clearance standards.

 

And why do they then taper in?

Edited by zephyr17

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I’m not sure about the bulging, but they do curve back in at the top. I always thought that was a clearance issue with NEC tunnels??

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They aren't straight above the maximum width just below the window band. They start tapering back in immediately, well before the curve for the roof. Again, I am assuming that all the infrastructure (tunnels, platforms) conforms to at least the most restrictive clearance plate, the "unlimited interchange" Plate B.

Edited by zephyr17

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Probably to save material costs. It takes less metal to make a car design like the Viewliners than a squared off one like the Horizons. However conversely it takes more man power to make a Viewliner-like design than a Horizon-like design (not counting the corrugation)... just looking at cut & weld time that is, there may be more manpower variables beneath the skin.

 

peter

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Heritage cars are 10 feet wide. Amfleet and Horizon are 10 feet, 6 inches wide, at their widest. The Amfleet curve in at floor level, but the Horizon cars have a "notch"....both for the purpose of clearing high level platforms. Believe Viewliners are also 10 feet, 6 inches max, and angle in for the same reason.

Superliner's are 10 feet, 4 inches wide. They do not operate by high level platforms, AFAIK....

Edited by railiner

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(apparently really subtle in the case of Superliners they always looked straight to me past the flare on the bottom, which is demanded by clearance plates).

Superliners don't curve. They're completely straight, though the bottom is slanted inwards.

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Probably to save material costs. It takes less metal to make a car design like the Viewliners than a squared off one like the Horizons. However conversely it takes more man power to make a Viewliner-like design than a Horizon-like design (not counting the corrugation)... just looking at cut & weld time that is, there may be more manpower variables beneath the skin.

 

peter

I doubt that that's the reason. Compared to the cost of all the materials and work that goes into building a sleeper, that would be pretty insignificant. Sleepers are not cheap to manufacture, and are designed for comfort, so one would imagine the focus was on offering as much space as possible, and not on any slight savings by using less metal.

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The Budd Metroliner was the basis for the Amfleet, and since the Metroliners were supposed to compete with the airlines, and the world was experiencing a bit of an obsession with air travel, they wanted the Metroliners to have the appearance and style of an airplane. Hence the small windows and round body (though the tiny windows were also chosen because people tended to throw rocks at them back then).

 

 

More than a decade prior to the original Metroliner's, Budd built for the PRR, a lghtweight, tubular design train, that carried its own HEP generator. This was called The Keystone...

The train was not even 10 feet wide, so no clearance problems. Ultimately the one-off, like many other mid-century 'test' train designs proved to be a failure...

 

http://streamlinermemories.info/?p=2276

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Maybe just because some designer thought they are more pleasing on the eye that way.

 

I like the effect very much.

 

Also, many tilting trains have a honeycomb-shaped cross-section. They taper at the top so they stay within plate in the curves and they taper at the bottom because of platforms, or because they don't strictly tilt but rotate around a middle point, and they would be out of plate on the other side in curves too. Thus the hexagonal cross-section makes most efficient use of space.

 

Now Viewliners don't tilt, and were never intended to as far as I know. But mayne some designer thought it would be cool to create the impression that they could.

 

A bit like certain cases of streamlining having little to do with real wind-tunnel aerodynamics but much to do with designers wanting to create the suggestion that something is aerodynamic.

Edited by cirdan

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It's so the cars can provide extra shoulder room and still clear high-level platforms. The "bulge" allows an additional 6" of width where it is most needed. The cars have to taper to the top due to the envelope that allows for the rocking of cars through tight clearances like in a tunnel. The Amfleet "tube" or the Acela "taper" provide 10' 6" width approximately at the armrest level otherwise not possible with a straight wall design.

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