schlimmRefering to the Canadian TSB (or the NTSB) as a "political entity" is a desperate attempt at smearing a very respected independent agency. The trade journal is a good reference, but hardly the final arbiter since they do not investigate accidents.
Iam not'smearing' them; I'm just pointing out that their published explanation of rail/wheel interaction is not as well developed, or as 'in accord with known facts', as the published explanations in something like Interface Journal.
And I do not think you can deny that the Canadian TSB is first and foremost a political agency. Perhaps you stopped reading the description at 'independent' before you got to the word 'federal'. From the Canadian TSB site:
To instill confidence in the public regarding the transportation accident investigation process, it is essential that an investigating agency be independent and free from any conflicts of interest when investigating accidents, identifying safety deficiencies, and making safety recommendations. As such, the TSB is an independent agency, separate from other government agencies and departments, that reports to Parliament through the Leader of the Government in the House of Commons.
I meant 'political' as a synonym for 'government' -- not implying that the TSB 'plays politics' or skews its investigations for expediency or cover-up/blame shifting, etc.
The term "political" these days is not synonomous with government, except in the minds of those who believe government (and media) is the enemy. Hopefully, now you know. And the author of the article in the trade journal to which you referred is neither an engineer, scientist or researcher. He is a good journalist. Investigation teams at the TSB consist primarily of folks with background in the industry and engineers, not political appointees.
C&NW, CA&E, MILW, CGW and IC fan
schlimmThe term "political" these days is not synonymous with government, except in the minds of those who believe government (and media) is the enemy. Hopefully, now you know.
Upon reflection, I will observe that distinction going forward.
Investigation teams at the TSB consist primarily of folks with background in the industry and engineers, not political appointees.
Without question. I also firmly believe this is true of most if not all the 'group' participants in NTSB investigations.
schlimm The term "political" these days is not synonomous with government, except in the minds of those who believe government (and media) is the enemy. Hopefully, now you know. And the author of the article in the trade journal to which you referred is neither an engineer, scientist or researcher. He is a good journalist. Investigation teams at the TSB consist primarily of folks with background in the industry and engineers, not political appointees.
One thing that has recently been noted by several senior railway officials that I know is that back in the significant downsizing days it was easy for FRA and similar bodies to pick up experienced railroaders for their staff. With the baby boomer retirement bubble and the health of the industry, that pool of talent has all but vanished. It has been pointed out that FRA now lacks staff with significant industry experience. The head of the signal division is sometimes pointed out as an example, he was once a signal maintainer lacking any design experience. I imagine TSB is under similar pressure.
My one close experience with NTSB was also an eye opener. It was a derailment that potentially involved both track and mechanical issues. The NTSB investigator (who's name I won't mention as he is still very prominent in railway safety circles) was very focused on the track feature present at the derailment site. Other experts felt that the feature was insufficient to have caused the derailment . Some mechanical issues were noted on the derailed car but it was unclear if those were pre or post derailment. Vehicle dynamics computer modeling indicated that the track feature alone was insufficient to induce derailment causing forces, but given those mechanical deficiencies a derailment was possible. The NTSB investigator virtually ignored that finding and focused on the track feature in his report. He felt that even if that feature wasn't a FRA violation it shouldn't be allowed. My point is that even if a finding comes from a presumably unbiased body, it may still be subject to someone's agenda.
tdmidget I'm with Wislish. The transportation safety Boards are at best, investigators. They most emphatically are not experts. Their job is to ask questions, not answer them. Their ridiculous premise that track irregularity on one corner might affect the other corner would require all wheels to be rigidly affixed to the car and unsprung. What we have is people who are supposed be asking questions trying to answer them.
I'm with Wislish. The transportation safety Boards are at best, investigators. They most emphatically are not experts. Their job is to ask questions, not answer them. Their ridiculous premise that track irregularity on one corner might affect the other corner would require all wheels to be rigidly affixed to the car and unsprung. What we have is people who are supposed be asking questions trying to answer them.
Euclid tdmidget I'm with Wislish. The transportation safety Boards are at best, investigators. They most emphatically are not experts. Their job is to ask questions, not answer them. Their ridiculous premise that track irregularity on one corner might affect the other corner would require all wheels to be rigidly affixed to the car and unsprung. What we have is people who are supposed be asking questions trying to answer them. T. D. Midget, I don’t think that is the case. It is true that a perfectly stiff and rigid wheel carriage would be the absolute in non-equalization. With that, you would only have the small ability for equalization arising from the twist of the car body that the TSB mentions. But I believe that equalization can be compromised without a perfectly rigid carriage. And when in is compromised, the car body flexibility could play a small role in mitigating the problem. A freight car standing on level track will have perfect weight equalization on all eight wheels. But when in motion, there is no guarantee of weight equalization if it starts to rock side to side. What I conclude from the TSB comment is that of course car body flexibility plays a role in the wheel load equalization. What they fail to provide is just how big the role is. When they say “as one corner of the car travels over a track irregularity, the diagonally opposite corner of the car may experience some degree of wheel unloading as a result of the rigidity of the car body,” they are correct, but what they leave out is the exact magnitude of the effect. There is that old story about how a railroad rail deflects when a fly lands on it. Here is the quote from the TSB: “Excerpt from TSB of Canada Torsional Rigidity of Tank Cars Stub sill tank cars, similar to the tank cars that derailed in this occurrence, utilize the tank itself as a centre sill and are more rigid than traditional rail cars. A consequence of this is that, as one corner of the car travels over a track irregularity (for example, a turnout or entrance/exit spiral to a curve), the diagonally opposite corner of the car may experience some degree of wheel unloading as a result of the rigidity of the car body. For other types of rolling stock, which can twist more readily as they negotiate varying track structure, vertical unloading at the diagonally opposite corner will not occur to the same extent. In this case, the forces at one end of the car will not necessarily affect the truck at the opposite end.”
Testing FACTS to support the theory? Unless the TSB has tested fact to support their allegation they need to keep quiet - they have become as bad as 'yes, but'.
Never too old to have a happy childhood!
BaltACD Testing FACTS to support the theory? Unless the TSB has tested fact to support their allegation they need to keep quiet - they have become as bad as 'yes, but'.
EuclidBut I don’t need a test to show what they have said.
If we all had your level of expertise on every subject the problem would be solved in one minute.
Norm
Wizlish TSB,quoted by wanswheel Stub sill tank cars, similar to the tank cars that derailed in this occurrence, utilize the tank itself as a centre sill and are more rigid than traditional rail cars. A consequence of this is that, as one corner of the car travels over a track irregularity (for example, a turnout or entrance/exit spiral to a curve), the diagonally opposite corner of the car may experience some degree of wheel unloading as a result of the rigidity of the car body. Someone who is an expert in railcar dynamics comment please: this statement does not seem particularly accurate to me if the car in question is riding on three-piece trucks with a typical amount of side bearing clearance or long-travel CCSBs. The actual resultant of any torsion from 'excess rigidity' of a tubular tank over a centersill car, after the side bearing compliance and the geometry of the equalizing action of the three-piece truck sideframes is included, does not seem to be of the magnitude to produce a massive propensity toward derailment by itself. That's historically been one of the major selling points about three-piece trucks in general -- why interchange cars could run 90 mph on the Super C without spilling left and right with regularity, or why the U.S. Army Corps of Engineers had so much trouble derailing their test train with explosive sabotage in WWII, for a couple of examples. Meanwhile, look at Tuzik's article in the Interface Journal link wanswheel provided: I see evidence there that high lateral/low vertical force often tends to turn rails over, rather than causing wheels to lift -- something pointedly absent from the TSB's little graphical 'analysis' as provided. But I'll wait for voices with more experience, for what do I know?
TSB,quoted by wanswheel Stub sill tank cars, similar to the tank cars that derailed in this occurrence, utilize the tank itself as a centre sill and are more rigid than traditional rail cars. A consequence of this is that, as one corner of the car travels over a track irregularity (for example, a turnout or entrance/exit spiral to a curve), the diagonally opposite corner of the car may experience some degree of wheel unloading as a result of the rigidity of the car body.
Someone who is an expert in railcar dynamics comment please: this statement does not seem particularly accurate to me if the car in question is riding on three-piece trucks with a typical amount of side bearing clearance or long-travel CCSBs. The actual resultant of any torsion from 'excess rigidity' of a tubular tank over a centersill car, after the side bearing compliance and the geometry of the equalizing action of the three-piece truck sideframes is included, does not seem to be of the magnitude to produce a massive propensity toward derailment by itself. That's historically been one of the major selling points about three-piece trucks in general -- why interchange cars could run 90 mph on the Super C without spilling left and right with regularity, or why the U.S. Army Corps of Engineers had so much trouble derailing their test train with explosive sabotage in WWII, for a couple of examples.
Meanwhile, look at Tuzik's article in the Interface Journal link wanswheel provided: I see evidence there that high lateral/low vertical force often tends to turn rails over, rather than causing wheels to lift -- something pointedly absent from the TSB's little graphical 'analysis' as provided.
But I'll wait for voices with more experience, for what do I know?
I did stay in a Holiday Inn Express recently, so...
I agree with your comments. The effect of carbody torsion on wheel loading is going to be really, really small. The "moment arm" of the center bowl/pin radius won't allow for much force out at the bolster edges, and I can't imagine a sill-less tank car being that much more torsionally rigid than a house car for it all to add up to anything measurable.
The lateral and vertical forces experienced in normal operation swamp all of this.
There are three reasons I can think of why the Super C hung in there at 90 mph. One is those 90' flats help a good bit with stability. Two is good track. Three is jointed rail - irregularities tend to damp out hunting.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Are we sure track defects aren't bait causing oil trains?
Euclid I doubt that the natural flexibility of a railcar is intended to play any part in the suspension mechanics, springing, or equalization. For practical purposes, a railcar is intended to be rigid.
you may feel that the car is intended to be rigid but in fact it isn't. This plays a significant enough role in vehicle dynamics that the 2 most common vehicle dynamics simulation programs (NUCARS and Vampire) require car body stiffness values as inputs to predict wheel/rail forces. Of course a number of other parameters are required as well, but carbody stiffness can't just be assumed away as you are proposing .
Buslist Euclid I doubt that the natural flexibility of a railcar is intended to play any part in the suspension mechanics, springing, or equalization. For practical purposes, a railcar is intended to be rigid. you may feel that the car is intended to be rigid but in fact it isn't. This plays a significant enough role in vehicle dynamics that the 2 most common vehicle dynamics simulation programs (NUCARS and Vampire) require car body stiffness values as inputs to predict wheel/rail forces. Of course a number of other parameters are required as well, but carbody stiffness can't just be assumed away as you are proposing .
Euclid Buslist Euclid I doubt that the natural flexibility of a railcar is intended to play any part in the suspension mechanics, springing, or equalization. For practical purposes, a railcar is intended to be rigid. you may feel that the car is intended to be rigid but in fact it isn't. This plays a significant enough role in vehicle dynamics that the 2 most common vehicle dynamics simulation programs (NUCARS and Vampire) require car body stiffness values as inputs to predict wheel/rail forces. Of course a number of other parameters are required as well, but carbody stiffness can't just be assumed away as you are proposing . I am not exactly assuming it away. I am sure it has to be accounted for and controlled. I am surprised if car body flexibility is intended to provide spring action to dampen ride irregularities, or to provide load equalization to the wheels, if that is what you are saying. I had assumed that not to be the case. When I said that freight car bodies, for practical purposes, are intended to be rigid, I just meant not intended to play a role in ride or suspension. I did not mean to imply that perfect rigidity was an actual objective.
Great ya but. The problem is that you are looking at it backwards. The car body is not intended to provide flexibility, but like gravity it exists, a completely rigid carbody would be expensive to produce . Therefor the suspension must be designed to accommodate some flexibility. Now along comes a rigid tankcar and a standard M976 truck may not play well with it. If carbody stiffness was such a minor factor it would not be necessary to account for it in a modeling exercise.
Buslist Great ya but. The problem is that you are looking at it backwards. The car body is not intended to provide flexibility, but like gravity it exists, a completely rigid carbody would be expensive to produce . Therefor the suspension must be designed to accommodate some flexibility. Now along comes a rigid tankcar and a standard M976 truck may not play well with it. If carbody stiffness was such a minor factor it would not be necessary to account for it in a modeling exercise.
Euclid Buslist Great ya but. The problem is that you are looking at it backwards. The car body is not intended to provide flexibility, but like gravity it exists, a completely rigid carbody would be expensive to produce . Therefor the suspension must be designed to accommodate some flexibility. Now along comes a rigid tankcar and a standard M976 truck may not play well with it. If carbody stiffness was such a minor factor it would not be necessary to account for it in a modeling exercise. No, I am not looking at it backwards. You started by saying that car bodies are not intended to be rigid. I responded that I did not mean to say they were intended to be rigid, but just not intended to play a role in suspension. Now you come back and tell me that car bodies are not intended to be flexible. So, fine; they are not rigid and not flexible. Playing a role in the suspension (as the TSB implies) is not the same as accounting for car body flexibility in designing the truck suspension. When you say that the higher rigidity of tank cars can compromise the truck suspension, do you mean that this exists as a defect in tank cars; or are the trucks specially modified for tank cars to accommodate the extra rigidity?
Another Great ya but, facts just don't register with you do they!
Once again you just don't get it . Car bodies are not designed to be rigid, never have, never will. But like gravity it is a factor you need to consider when designing a suspension system. You keep saying that you can't believe car body flexibility is designed in to accomudate track irrugerslitaries, I'm saying it's not designed in for that purpose, but it's a fact of life so accommodate it.
Tired of trying to educate you when you don't listen so over and out!
"Tired of trying to educate you when you don't listen so over and out!"
Bucky never has, and likely never will, see the viewpoints of others.
BuslistTired of trying to educate you when you don't listen so over and out!
Euclidthat tank cars are inherently more prone to derailments than any other type of rolling stock.
But you have been saying that all along, together with the position that oil tank cars cause track damage that causes derailments.
You once claimed that I have no knowledge of your experience or expertise in railroading. You are right on that score, and judging from your repeated "yes but" expertise on your part is lacking. Would it be too much to ask for some credentials rather than simply listening to your inane and uninformed rants.?
The original hypothesis of this thread and the supporting TSB report is that oil trains cause or exacerbate track defects. That implies there is something different about oil trains. So what is different about an oil train? One obvious difference is that it consists of tank cars. So what are all the things that are unique to a tank car? There are dozens of things that are unique. The vast majority of them will have no significant negative consequence (e.g. tank cars are round, therefore they have a different coefficient of friction for cross winds than other cars, however it is much less than most other cars, so that has less track forces due to cross winds compared to other car types, net result, no significant negative consequence for cross section).
One of the thing that is frustrating is that people go off with solutions or conclusions with no understanding or data. A lot of these "solutions" are focused on a single point of failure and there is no understanding of the unintended consequences that point solution can have. Take an earlier discussion on oil trains when it was proposed that oil trains have some new even more "rigid" coupling between the cars and that they be beefed up to be an impregnable shell..
Go back and look at the cement train derailment near Corsicana a few weeks ago. There were 20 something cars derailed and on their sides. Only a half dozen or so of the cars actually derailed in the washout, the rest were derailed when the washout cars turned over and the high strength couplers on the heavy cement cars twisted the following cars, causing them to roll over too. If an oil train had even more rigid couplers than presently available, and did derail, it could actually result in MORE cars, not fewer cars being derailed. I'm sure the proponents of the new coupling will point out that all the cars were in a row on their sides. That's nice, but any car not upright and on the track is a risk, any car derailed is a potential problem and should be avoided. In addition we are currently discussing how the tubular design of a tank car is more rigid than other "box" shapes. If the rigidity of a tank car does have some negative consequences regarding how it interacts with the track, then its very likely that an even thicker, more armored, more rigid tank car design would in fact exacerbate those negative consequences and increase track damage (if the tank car design is a factor).
Dave H. Painted side goes up. My website : wnbranch.com
dehusman The original hypothesis of this thread and the supporting TSB report is that oil trains cause or exacerbate track defects. That implies there is something different about oil trains. So what is different about an oil train? One obvious difference is that it consists of tank cars. So what are all the things that are unique to a tank car? There are dozens of things that are unique. The vast majority of them will have no significant negative consequence (e.g. tank cars are round, therefore they have a different coefficient of friction for cross winds than other cars, however it is much less than most other cars, so that has less track forces due to cross winds compared to other car types, net result, no significant negative consequence for cross section). One of the thing that is frustrating is that people go off with solutions or conclusions with no understanding or data. A lot of these "solutions" are focused on a single point of failure and there is no understanding of the unintended consequences that point solution can have. Take an earlier discussion on oil trains when it was proposed that oil trains have some new even more "rigid" coupling between the cars and that they be beefed up to be an impregnable shell.. Go back and look at the cement train derailment near Corsicana a few weeks ago. There were 20 something cars derailed and on their sides. Only a half dozen or so of the cars actually derailed in the washout, the rest were derailed when the washout cars turned over and the high strength couplers on the heavy cement cars twisted the following cars, causing them to roll over too. If an oil train had even more rigid couplers than presently available, and did derail, it could actually result in MORE cars, not fewer cars being derailed. I'm sure the proponents of the new coupling will point out that all the cars were in a row on their sides. That's nice, but any car not upright and on the track is a risk, any car derailed is a potential problem and should be avoided. In addition we are currently discussing how the tubular design of a tank car is more rigid than other "box" shapes. If the rigidity of a tank car does have some negative consequences regarding how it interacts with the track, then its very likely that an even thicker, more armored, more rigid tank car design would in fact exacerbate those negative consequences and increase track damage (if the tank car design is a factor).
A point of clarification, please. Do you disagree with the TSB and if so, what is your basis for that in terms of your knowledge and experience or data? It is rather facile for others to dismiss Euclid for having no knowledge, no qualifications for making his speculations etc. (and his "yes, but" contortions exaccerbate that) but who on here is really in a position to refute the credentialed experts at the TSB or NTSB?
Euclid Buslist Tired of trying to educate you when you don't listen so over and out! Buslist, There is a context to this line of discussion that began with the TSB saying that tank cars are harder on the track than other types of rolling stock. The reason for that is, according to the TSB, that tank cars are more rigid. The TSB says a lack of torsional flexibility can interfere with wheel load equalization. I disagree with them by dismissing their contention that flexibility is intended to play any role in the equalization. Since you vehemently jumped on my case for having it all wrong, I assume that you agree with the TSB in that tank cars are inherently more prone to derailments than any other type of rolling stock. Is that what you are saying? Others here who are in the know agreed with my point of view. They say the TSB is biased, too political, does not have real railroaders on board, etc. They say flexibility cannot possibly play a role in equalization on any type of freight car because there is not enough flexibility to matter. Now you come along and insist that they and I are all wrong. So it is you and TSB warning us of the dangers of tank cars. Since you are the expert who educates all of us, it sounds to me like you should educate the government so they can order a tank car recall.
Buslist Tired of trying to educate you when you don't listen so over and out!
A recall? Please grow up! It has been widely recognised by vehicle dynamics experts that rigid body tank cars are slightly more prone to derailments on certain types of track irregularities. Do some research, a quick Google search last night produced around 20 papers that delt with the topic going back to the mid 90s. Stub sill tank cars have been around a long time with very little but well known issues. The focus should be on those track irregularities that are particularly vulnerable to issues with rigid body cars or on other suspension modifications to reduce the effect not a recall! The problem with the TSB report is that it focuses on the wrong thing and acts like this is something new!
Euclid Buslist, So you have tank cars that derail on track irregularities more than any other type of freight car, and your solution is to get rid of track irregularities. That’s rich.
No it's called cost effective, understand the concept? Thousands of tank cars, relatively limited number of track defects, got to be rich for your solution!
Over and out, you just don't get it!
Buslist Euclid Buslist, So you have tank cars that derail on track irregularities more than any other type of freight car, and your solution is to get rid of track irregularities. That’s rich. No it's called cost effective, understand the concept? Over and out, you just don't get it!
No it's called cost effective, understand the concept?
Euclid Buslist Euclid Buslist, So you have tank cars that derail on track irregularities more than any other type of freight car, and your solution is to get rid of track irregularities. That’s rich. No it's called cost effective, understand the concept? Over and out, you just don't get it! Cost effective? Who gets to decide what cost is too high and what cost is just right when oil trains are endangering the public?
Buslist Euclid Buslist Euclid Buslist, So you have tank cars that derail on track irregularities more than any other type of freight car, and your solution is to get rid of track irregularities. That’s rich. No it's called cost effective, understand the concept? Over and out, you just don't get it! Cost effective? Who gets to decide what cost is too high and what cost is just right when oil trains are endangering the public? . Another example of how you just don't get it!
. Another example of how you just don't get it!
schlimmA point of clarification, please. Do you disagree with the TSB and if so, what is your basis for that in terms of your knowledge and experience or data? It is rather facile for others to dismiss Euclid for having no knowledge, no qualifications for making his speculations etc. (and his "yes, but" contortions exaccerbate that) but who on here is really in a position to refute the credentialed experts at the TSB or NTSB?
Here's a clarification. I am not refuting either the TSB or NTSB reports. Nowhere in my post did I say whether they were wrong or they were right.
Euclid Buslist Euclid Buslist Euclid Buslist, So you have tank cars that derail on track irregularities more than any other type of freight car, and your solution is to get rid of track irregularities. That’s rich. No it's called cost effective, understand the concept? Over and out, you just don't get it! Cost effective? Who gets to decide what cost is too high and what cost is just right when oil trains are endangering the public? . Another example of how you just don't get it! Buslist, My premise is that if tank cars are unusually prone to derail on track irregularities; and prone to cause track irregularities; it would be cost effective to change tank cars so they are not unusually prone to these problems. You are the one who tells me that tank car flexibility/rigidity is accounted for in programs used to design the truck suspension. If the relatively higher rigidity of tank cars is accounted for in the design of truck suspension, why are tank cars still more prone to derail?
Like I said over and out, have better things to do with my time than to try to educate someone that doesn't want to be educated.
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