Railway ManRolling contact fatigue on the rail head is the present economic limit.
Rolling contact fatigue on the rail head is the present economic limit.
In other words, a wider gauge wouldn't be a benefit for hauling bulk commodities. A supporting point is that the South Africans are doing reasonably well with heavy haulage on their 3'6" lines. Intermodal wouldn't benefit much from wider gauge either, unless it was wide enough for two side by side trailers or containers and that would also run into axle loading limits.
A set of categories of freight that would benefit from a wider gauge, and a larger loading gauge are the various "oversize" loads, e.g. power plant components, refinery components, aerospace assemblies. A back-handed example with respect to power plants is Babcock & Wilcox's proposed new generation of nuclear reactors that are sized small enough to be transported by rail.
- Erik
Optimum gage does not matter at this time, but that does not mean that there is none. It largely does not matter because there is nothing that we can do about it now. However, it mattered a great deal back during the early development when everyone sought it and debated what the optimum gage was at that time.
Look at it this way: Say there are no railroads, but we have the whole concept fully designed except for the scale, which includes the gage. And with that concept design, we are free to change any of the details such as wheels, rails, suspension, car lengths, etc. Say we intend to build a national rail system where all the components must be interchangeable and/or standardized like they actually are today. Within this scenario, it is obvious that the choice of scale and gage is deadly serious because the optimum scale and gage will yield the maximum return on investment; and once committed and built, there can be no turning back. In this scenario, the choice of gage matters tremendously.
This scenario is of course totally hypothetical because there is no practical application of it today. Moreover, this scenario never fully occurred in the first place because the beginning fragments of railroad were free to experiment with gage because they did not interchange with each other. Nevertheless, the hypothetical example I cite does serve to highlight the original question posed as the title of this thread and place it into a context in which it can be understood.
An uninformed opinion: 60.173'-1.91". You asked. New 53' trailers could be loaded transversely on the cars, with room for 'taggers', and other trespassers, to walk around among them.
Hays (Older Army)
AnthonyV jeaton There are a number foreign rail systems operating on wider gauge track. Most of the lines in Spain and Portugal are 1668 mm (5' 5 2/3"), but Spain's high speed passenger lines are on 4' 8 1/2" track as that the standard for similar purposed lines in the most of the rest of Europe. Do these systems use rolling stock that is larger than those operating with standard gauge? Anthony V.
jeaton There are a number foreign rail systems operating on wider gauge track. Most of the lines in Spain and Portugal are 1668 mm (5' 5 2/3"), but Spain's high speed passenger lines are on 4' 8 1/2" track as that the standard for similar purposed lines in the most of the rest of Europe.
There are a number foreign rail systems operating on wider gauge track. Most of the lines in Spain and Portugal are 1668 mm (5' 5 2/3"), but Spain's high speed passenger lines are on 4' 8 1/2" track as that the standard for similar purposed lines in the most of the rest of Europe.
Do these systems use rolling stock that is larger than those operating with standard gauge?
Anthony V.
My understanding is that the loading gauge of the Spanish lines is smaller than that of North America......I believe their equipment is generally lighter..
"I Often Dream of Trains"-From the Album of the Same Name by Robyn Hitchcock
What more can you tell us about the Pilbara lines and how those high axel loadings are accommodated
Thanks,
Bill McDonald
Bill,
I had asked RWM about the same question a while back and his answer was pretty much what he wrote in his reply to me on 2/27 in this thread. Perhaps the best way to sum it up is painstaking attention to detail in maintenance of both the track ad rolling stock with particular attention to wheel and rail head profile.
If I were to hazard a guess, part of the secret sauce is the geometry of the contact patch between the wheel and rail, with the goal of spreading the patch along the width of the wheel/rail as much as reasonably practical. The goal behind this is to reduce peak contact pressure, which then should reduce metal fatigue.
Metallurgy is also important.
BNSFwatcher An uninformed opinion: 60.173'-1.91". You asked. New 53' trailers could be loaded transversely on the cars, with room for 'taggers', and other trespassers, to walk around among them. Hays (Older Army)
Or...1.91' x 60.173'. Just stand 'em endwise. A little more work on overhead clearences but it saves having to relocate platforms, crossing gates, etc. Easier to unload, too-just tip them onto the trailer chassis (might not work so well for electronics but pillow shipments should be OK).
It looks like we're on to something. Or possibly just on something...
It seems to me that we are giving more credit due to track gauge. Up to a point it wouldn't determine the car width. If we kept the same gauge and magically made all bridges and tunnels 2 feet wider then we would start see wider car being made that worked fine on our existing guage. Also if we kept the current gauge but redesigned the railhead and wheels to be wider, wouldn't that solve many of the metalurgical problems as well as adhesion. Since we are dreaming, even a railhead that is 1 inch wider would make a big difference in adhesion.
A different gage allows the possibility of a different scale of all of the details of track and train. So the increasing of standard gage to say 5’-4” could simply allow larger trains in every detail and dimension.
I understand the point that the rail/wheel contact area has reached its metallurgical limit. But that limit is only part of the limits of standard gage. Increasing gage could also allow and justify increasing the area of the rail/wheel contact point, thus increasing its capacity accordingly.
This is the latest of several threads where there has been debate about the adequacy and inadequacy of standard gauge particularly in North America...and again I'm struck by the position some have that articulated, doublestack well cars, multilevel vehicle carriers (autoracks) and 286,000 lbs. gross bulk cars are in some way "too small"....I don't know how, objectively, one can talk about an "ideal gauge" and I'm sure a civil engineer would not look at it this way...Loading gauge is what is important in the real world...
carnej1 This is the latest of several threads where there has been debate about the adequacy and inadequacy of standard gauge particularly in North America...and again I'm struck by the position some have that articulated, doublestack well cars, multilevel vehicle carriers (autoracks) and 286,000 lbs. gross bulk cars are in some way "too small"....I don't know how, objectively, one can talk about an "ideal gauge" and I'm sure a civil engineer would not look at it this way...Loading gauge is what is important in the real world...
But loading gage has a relationship with track gage. They are not independent of each other.
The current wallpaper I have on my computer shows rush hour at Melbourne Southern Cross with three trains waiting for departure behind V/Line N-class locomotives. Victoria uses a gauge of 5'3" and I see no appreciable differences in scale between standard gauge and broad gauge equipment.
CSSHEGEWISCH The current wallpaper I have on my computer shows rush hour at Melbourne Southern Cross with three trains waiting for departure behind V/Line N-class locomotives. Victoria uses a gauge of 5'3" and I see no appreciable differences in scale between standard gauge and broad gauge equipment.
There does not necessariliy have to be a difference in size betwen the components of two rail systems of different gages. It's just that increasing the size of equipment ulitmatley requires increasing the gage.
if i can stick in my two cents worth - one big factor in shelling caused by increasing axle loads is rail/wheel hysteresis, caused by steel being stressed beyond its elastic limit. half-measures such as the 36" wheel for 100-ton cars and 38" for the 120's do help, but going to a 42" wheel as used on baldwin diesels,increases the rail-to-wheel contact area by a full 10% for the same depth of 'dent'. a really big wheel would further reduce unit stress but would have to be mounted outside the carbody; WIDE GAUGE! you'd still have the rail-support problems with ties and ballast and subgrade, but slabtrack would help there. as for bridges - the cooper loading is based on wheel spacing (longitudinal) as well as axle loading. i was astonished to find the pennsy's E6s atlantic, with its driving axle load of over 70,000 lbs, had a cooper rating of only E-43, because of the distance between its axles. replace the standard freight-car truck with air-cushion wheelsets every 8or 10 ft. along the carbody (air-equalized) and you've reduced the cooper loading and also vastly decreased the beam strength needed in the carbody. -big duke
Bucyrus carnej1 This is the latest of several threads where there has been debate about the adequacy and inadequacy of standard gauge particularly in North America...and again I'm struck by the position some have that articulated, doublestack well cars, multilevel vehicle carriers (autoracks) and 286,000 lbs. gross bulk cars are in some way "too small"....I don't know how, objectively, one can talk about an "ideal gauge" and I'm sure a civil engineer would not look at it this way...Loading gauge is what is important in the real world... But loading gage has a relationship with track gage. They are not independent of each other.
bigduke76 if i can stick in my two cents worth - one big factor in shelling caused by increasing axle loads is rail/wheel hysteresis, caused by steel being stressed beyond its elastic limit. half-measures such as the 36" wheel for 100-ton cars and 38" for the 120's do help, but going to a 42" wheel as used on baldwin diesels,increases the rail-to-wheel contact area by a full 10% for the same depth of 'dent'. a really big wheel would further reduce unit stress but would have to be mounted outside the carbody; WIDE GAUGE! you'd still have the rail-support problems with ties and ballast and subgrade, but slabtrack would help there. as for bridges - the cooper loading is based on wheel spacing (longitudinal) as well as axle loading. i was astonished to find the pennsy's E6s atlantic, with its driving axle load of over 70,000 lbs, had a cooper rating of only E-43, because of the distance between its axles. replace the standard freight-car truck with air-cushion wheelsets every 8or 10 ft. along the carbody (air-equalized) and you've reduced the cooper loading and also vastly decreased the beam strength needed in the carbody. -big duke
Well, your 'two cents worth' makes a lot more 'sense' to me than just that. I agree completely with your summary and quick analysis of the alternatives - wish I'd thought of that as well. The point being, of course, that a wider gauge and the commensurate heavier payloads - otherwise, why bother ? - starts to introduce all kinds of other adverse effects and drives up the costs elsewhere to cope with or mitigate them, as the case may be - everything from rail wear to more wheels to different carbody configurations, etc.
If you had a special-purpose rail line - say, one that hauled only feathers, or what is maybe close to the same thing, sugar cane, or even people - you might find that wide gauge and lightly-built cars with only 4 wheels per car, etc. would work just fine for you.
In contrast, a line that hauled really heavy mineral concentrates - say, lead - would need much shorter cars and more wheels, and a narrow-gauge might work just fine for you.
Actually, considering your last thought - do you remember the Aeronca [sp ?] segmented aluminum coal car that was constructed as a demonstrator for the Southern Railway back in the 1960's ? Or better yet - consider a train of iron ore cars - 'jennies'. Those are almost continuous wheelsets one right after another - sometimes it's hard to tell from the wheel/ axle spacing alone where one car ends and the next one begins. [I'll see if I can find photos to illustrate each of these.] You're right about decreasing the needed carbody ''beam strength'' to carry it and the payload across and between the trucks or axles, and reducing the equivalent Cooper's loading - at least in the upper portions of the bridge's superstructure, where the axle load has its biggest influence, such as the 'stringers' - but not so much in the bigger main members down lower in the bridge, which are more than a car-length or so long.
Another radical change that would reduce the rail stress and shelling is to change either the rail head profile and/ or the wheel profile or contour. The former is typically rounded - the 136-lb. AREA section has a 10'' radius - whereas the latter is typically a plane or cone with a tread taper of 1:20 or so, but which rapidly becomes 'hollow-worn' in service. That is no doubt due to the stress concentration - the theoretical intersection of the wheel tread's cone with the rounded rail head is a mere point, not as much as a line or even a defined area. For example, see - The effect of hollow-worn wheels on vehicle stability in straight track, in Volume 258, Issues 7-8, March 2005, Pages 1100-1108, of Contact Mechanics and Wear of Rail/Wheel Systems. But I digress . . . .
- Paul North.
From RAILWHALES - WEIGHT AND AXLES - under ''Unusual Designs'', about 2/3 of the way down the webpage, at -
http://www.railgoat.railfan.net/railwhales/a-axles.htm
''In August 1965, aircraft builder Aeronca Manufacturing Co. of Middletown, Ohio built a 260-ton, 8-axle aluminum hopper car for the Southern Railway. This 103-foot car consisted of four permanently-connected 25-foot units, each riding on two axles. Southern 100 was loaded with inovations, including disk brakes, 7x12 bearings, and 38-inch wheels. The latter features gave the car a gross rail load of 630,000 pounds. It had a light weight of 96,000 pounds, a load limit of 534,000 pounds, and a volume of 9,000 cubic feet.''
See - Southern 100 - A new concept with a bright future
at - http://southern.railfan.net/ties/1965/65-8/s100.html
and Southern 100 means savings in transportation costs
at - http://southern.railfan.net/ties/1965/65-8/one.html
DM&IR ore 'jennies' wheels -
http://www.railpictures.net/viewphoto.php? id=119457
carnej1 Bucyrus carnej1 This is the latest of several threads where there has been debate about the adequacy and inadequacy of standard gauge particularly in North America...and again I'm struck by the position some have that articulated, doublestack well cars, multilevel vehicle carriers (autoracks) and 286,000 lbs. gross bulk cars are in some way "too small"....I don't know how, objectively, one can talk about an "ideal gauge" and I'm sure a civil engineer would not look at it this way...Loading gauge is what is important in the real world... But loading gage has a relationship with track gage. They are not independent of each other. ...In the real world of actual railroad companies the significant increases in loading gauge have allowed larger and larger equipment which is one way that capacities have increased. Debates about how wide apart the rails should be had validity back when the Erie RR was built (to 5 foot gauge) but in the 21st century standard gauge is considered the best practice for heavy haul and HSR in much of the world and these "wouldn't it be great if we had an X foot super broad gauge system"arguments strike me as akin to the Medeival philosophers who engaged in serious arguments about how many angels could dance on the head of a pin. Of course standard gauge is not "perfect" but to quote the old General "perfect is the enemy of good enough"..
That is all true, but it does not address the question of this thread. I agree that arguments about the perfect gage were valid back in the pioneering era. Not only were they valid then, but they were deadly serious as well. The wrong choice could ruin the investment. And the right choice required predicting the future; and not just the actual future traffic, but the subjectively guided human consensus as well. Back then, gage was defended like ideology, spawning terms like “gage war.”
Standard gage is considered best practice today only because there is no practical alternative. There simply could be no engineering/economic argument that we should actually change standard gage. That horse has left the barn. And I agree that there is great truth in the saying that "perfect is the enemy of good enough.” But I have a saying that, “Standard is the enemy of perfect.”
So while the question of optimum gage was an essential, practical question in the pioneering era, that does not mean that the question does not still exist today. It may only be an academic question today, but so what?
Increases in capacity have indeed been raised by increasing the loading gage, as you say, but it has about reached its limit. And that limit is track gage. So I submit that today’s traffic levels have reached a point where they put pressure on raising the track gage if it were possible to do so.
Bucyrus [snip] Increases in capacity have indeed been raised by increasing the loading gage, as you say, but it has about reached its limit. And that limit is track gage. So I submit that today’s traffic levels have reached a point where they put pressure on raising the track gage if it were possible to do so.
I'm not aware of a pressure to increase the track gage that is being caused by any actual or real traffic levels - only theoretical discussions such as this one. And any such pressure would largely be limited to light-loading commodities, mainly passengers - e.g., BART.
As to freight and heavy-haul commodities, the limit is not only track gage, but also rail stresses and wear, and extrapolating from that, more generally economics. That effect is reflected in such things as more complex vehicles - wheel sizes, axle arrangements, etc. - and more expensive materials and/ or maintenance, etc. - to either preclude or cope with the increasingly costly effects of the heavier loads that are now possible within even the existing track gage. That trend line is clear for those who can see the data - I doubt that fully-informed engineering for a new operation would seriously consider a much wider gauge, even if they could, and aside from the 'standardization' of parts and equipment problems, too. Considering all of the costs, such a wide-gage operation would likely just cost more than a similar standard-gage operation. Where's the benefit in that ?
Paul_D_North_Jr Bucyrus [snip] Increases in capacity have indeed been raised by increasing the loading gage, as you say, but it has about reached its limit. And that limit is track gage. So I submit that today’s traffic levels have reached a point where they put pressure on raising the track gage if it were possible to do so. I'm not aware of a pressure to increase the track gage that is being caused by any actual or real traffic levels - only theoretical discussions such as this one. And any such pressure would largely be limited to light-loading commodities, mainly passengers - e.g., BART. As to freight and heavy-haul commodities, the limit is not only track gage, but also rail stresses and wear, and extrapolating from that, more generally economics. That effect is reflected in such things as more complex vehicles - wheel sizes, axle arrangements, etc. - and more expensive materials and/ or maintenance, etc. - to either preclude or cope with the increasingly costly effects of the heavier loads that are now possible within even the existing track gage. That trend line is clear for those who can see the data - I doubt that fully-informed engineering for a new operation would seriously consider a much wider gauge, even if they could, and aside from the 'standardization' of parts and equipment problems, too. Considering all of the costs, such a wide-gage operation would likely just cost more than a similar standard-gage operation. Where's the benefit in that ? - Paul North.
If it did cost more, there would be no benefit, but the underlying assumption is that the optimum gage would cost the least for what it produces. But again, the question is only posed in terms of a scenario of being unencumbered by the existing standard gage system. So while it is a completely practical question, there is nothing we can do about the answer. I doubt that we could even answer it. But nevertheless, it is a question with an answer.
When I speak of pressure to increase the track gage, I do not mean pressure from individuals actually proposing a gage change. The pressure is from rising traffic levels. I am just making the observation that rising traffic levels have resulted in the increase of loading gage and other clearance factors to the limit of standard track gage. And because traffic levels are still increasing, it seems logical to assume that they are now putting pressure on track gage as well as all the other physical limitations.
Just looking at all the factors and probable engineering alternatives, and trying to process them intuitively, I would guess that the optimum gage for today is certainly more than 4’-8 ½”, but not radically more. Certainly it would not be over six feet.
Paul_D_North_Jr From RAILWHALES - WEIGHT AND AXLES - under ''Unusual Designs'', about 2/3 of the way down the webpage, at - http://www.railgoat.railfan.net/railwhales/a-axles.htm ''In August 1965, aircraft builder Aeronca Manufacturing Co. of Middletown, Ohio built a 260-ton, 8-axle aluminum hopper car for the Southern Railway. This 103-foot car consisted of four permanently-connected 25-foot units, each riding on two axles. Southern 100 was loaded with inovations, including disk brakes, 7x12 bearings, and 38-inch wheels. The latter features gave the car a gross rail load of 630,000 pounds. It had a light weight of 96,000 pounds, a load limit of 534,000 pounds, and a volume of 9,000 cubic feet.'' See - Southern 100 - A new concept with a bright future at - http://southern.railfan.net/ties/1965/65-8/s100.html and Southern 100 means savings in transportation costs High Capacity plus Low Weight equals Savings in Transportation Costs at - http://southern.railfan.net/ties/1965/65-8/one.html DM&IR ore 'jennies' wheels - http://www.railpictures.net/viewphoto.php? id=119457 - Paul North.
http://www.nisa.org/Technology.html
Thanks for that recollection and link, carnej1. I was thinking there was another experiment of that sort out there, but just wasn't making that connection. Reading through the linked narrative, the proponents obviously had high expectations of hauling more coal in less and shorter trains, thereby providing more capacity without adding tracks. Unfortunately, it doesn't seem to have worked out technically.
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