EuclidThe force is a reaction to slack run-in. The force that produces the dynamic load moves forward along the horizontal axis of the tank car. When it does, the oil moves forward, and the air it displaces moves rearward. So the impact tends to cause the oil to be separated from the air in a vertical plane. Whether it actually achieves that vertical separation depends on the dynamic force generated in the impact. Then after the impact, the oil and air move back to their original positions with the air on top and oil on the bottom. During the impact, the dynamic load is applied horizontally to the forward head of the tank. During this impact, all of the oil load moves as part of the dynamic force. Every single molecule of oil moves as the oil shifts its position and separates from the air in a vertical plane. The oil molecules move at differing speeds, in different directions, and over differing distances. Once the oil and air separate vertically, every molecule of oil is stopped from moving by the blockage of the leading tank head. That abrupt stopping of the oil is where the kinetic energy that produces the dynamic load comes from. It comes from the sum total of all molecules being stopped. However, some molecules will be moving faster than others, so as they are stopped, they will contribute differing individual amounts of kinetic energy to the total dynamic load. But the point is that the entire load of oil is involved in producing the dynamic load on the leading tank head. It is not just the amount of oil that equals part or all of the air space.
This is a far greater absurdity than anything Dave Husman has attributed to you.
Slack run-in causes the relatively viscous oil to move forward and up into the void space, with the air being displaced up and back. This is a very small portion of the oil in the car,and the 'energy' involved is no more than that amount being raised against gravity the relatively small distance corresponding to the area of the tank head that originally corresponded to the void.
Very simple and straightforward fluid mechanics describe how this works. There is no "vertical"separation of air and water, whatever that is, nor is there the sort of dramatic momentum transfer that would be observed of a solid object crashing into a decelerated structure. All you need to do to observe the behavior involved is to fill a transparent tube with an appropriately viscous fluid, and then slide it laterally against a stop (or tilt it a few degrees) with the end resting on an appropriately sensitive scale.
The only real topic of discussion here is whether there are RESONANT effects in the oil train structure -- either due to the large number of reasonably similar cars with 'mobile' internal loading, or the heavier overall weight and repeated characteristics of long unit trains of those cars. I think you would be far better served to examine whether liquid oil loading causes dangerous forces AFTER the cars derail, for example as they accelerate in roll as they tip over, instead of inventing rail-busting pseudoforces of the wrong magnitude, with the wrong amplification, acting in the wrong planes.
Dave HusmanEuclid neeeds to explain what force he is going to use to displace several tons (not the entire load, just the volume of the void) of oil up to the top of the tank car which would require the the void to be moved to another part of the car (it would be amusing to see where Euclid thinks the void is going to go, he may think it magically, instananeously materializes at the bottom of the oil.) If he can figure out how to move all the parts around inside the container, the mazimum lift would be limited to the average height of the void (probably something in the range of 6 inches), then he would have to figure out how to drop that oil, simulataneously moving the void from the bottom of the container to the top of the container near instantaeously (if he used magic to beam it to the bottom I guess he can magically beam it to back to the top). Now as the oil impacts the bottom of the tank car (assuming he can figure out all the above), since its contacting a curved surface the force will have a horizontal component towards the center (which balances out since the curve is the same on the left and right sides and the forces point towards the middle). The net result of that is to reduce the downward force.
In all fairness there is no mystery about what happens to the 'void' and the oil when the slack runs in. Oil sloshes forward, filling up the void at the top of the forward head (and, as noted, producing a transient reactive force upward as well as greater mass loading on the suspension at that end of the car) and the air in the void displaces to the rear. Tip any bubble level (or slosh gravy in the boat at Thanksgiving) and you will see how the void would move.
This is a small volume, and the 'additional' energy that goes into the track is no greater than the additional gravitational potential energy as the forward end 'fills up', and the energy that hits the forward end of the car has no more inertial impact than the (rapidly closing!) area of the void on the head as far as damage to the tank structure is concerned.
Wizlish,
Who are you responding to? You appear to be quoting me, but you are acutally quoting Dave Husman.
.
Wizlish Euclid The force is a reaction to slack run-in. The force that produces the dynamic load moves forward along the horizontal axis of the tank car. When it does, the oil moves forward, and the air it displaces moves rearward. So the impact tends to cause the oil to be separated from the air in a vertical plane. Whether it actually achieves that vertical separation depends on the dynamic force generated in the impact. Then after the impact, the oil and air move back to their original positions with the air on top and oil on the bottom. During the impact, the dynamic load is applied horizontally to the forward head of the tank. During this impact, all of the oil load moves as part of the dynamic force. Every single molecule of oil moves as the oil shifts its position and separates from the air in a vertical plane. The oil molecules move at differing speeds, in different directions, and over differing distances. Once the oil and air separate vertically, every molecule of oil is stopped from moving by the blockage of the leading tank head. That abrupt stopping of the oil is where the kinetic energy that produces the dynamic load comes from. It comes from the sum total of all molecules being stopped. However, some molecules will be moving faster than others, so as they are stopped, they will contribute differing individual amounts of kinetic energy to the total dynamic load. But the point is that the entire load of oil is involved in producing the dynamic load on the leading tank head. It is not just the amount of oil that equals part or all of the air space. This is a far greater absurdity than anything Dave Husman has attributed to you. Slack run-in causes the relatively viscous oil to move forward and up into the void space, with the air being displaced up and back. This is a very small portion of the oil in the car,and the 'energy' involved is no more than that amount being raised against gravity the relatively small distance corresponding to the area of the tank head that originally corresponded to the void. Very simple and straightforward fluid mechanics describe how this works. There is no "vertical"separation of air and water, whatever that is, nor is there the sort of dramatic momentum transfer that would be observed of a solid object crashing into a decelerated structure. All you need to do to observe the behavior involved is to fill a transparent tube with an appropriately viscous fluid, and then slide it laterally against a stop (or tilt it a few degrees) with the end resting on an appropriately sensitive scale. The only real topic of discussion here is whether there are RESONANT effects in the oil train structure -- either due to the large number of reasonably similar cars with 'mobile' internal loading, or the heavier overall weight and repeated characteristics of long unit trains of those cars. I think you would be far better served to examine whether liquid oil loading causes dangerous forces AFTER the cars derail, for example as they accelerate in roll as they tip over, instead of inventing rail-busting pseudoforces of the wrong magnitude, with the wrong amplification, acting in the wrong planes.
Euclid The force is a reaction to slack run-in. The force that produces the dynamic load moves forward along the horizontal axis of the tank car. When it does, the oil moves forward, and the air it displaces moves rearward. So the impact tends to cause the oil to be separated from the air in a vertical plane. Whether it actually achieves that vertical separation depends on the dynamic force generated in the impact. Then after the impact, the oil and air move back to their original positions with the air on top and oil on the bottom. During the impact, the dynamic load is applied horizontally to the forward head of the tank. During this impact, all of the oil load moves as part of the dynamic force. Every single molecule of oil moves as the oil shifts its position and separates from the air in a vertical plane. The oil molecules move at differing speeds, in different directions, and over differing distances. Once the oil and air separate vertically, every molecule of oil is stopped from moving by the blockage of the leading tank head. That abrupt stopping of the oil is where the kinetic energy that produces the dynamic load comes from. It comes from the sum total of all molecules being stopped. However, some molecules will be moving faster than others, so as they are stopped, they will contribute differing individual amounts of kinetic energy to the total dynamic load. But the point is that the entire load of oil is involved in producing the dynamic load on the leading tank head. It is not just the amount of oil that equals part or all of the air space.
That is a very coherent explanation which I appreciate. However, if one returns to early posts, I recall some experts with credentials (see below) who seemed to think the sloshing could have a significant effect in some way making derailments more likely. Are you disputing that or just Euclid's diversion?
"Weight, oil sloshing and cold temperatures are among the issues that might be exacerbating the problem, according to rail safety experts.
Investigators at Safety Transportation Board Canada, which is investigating the eight accidents that have occurred in that country, are beginning to suspect that the oil trains are causing unusual track damage.
“Petroleum crude oil unit trains transporting heavily loaded tank cars will tend to impart higher than usual forces to the track infrastructure during their operation,” the safety board said in a report this year. “These higher forces expose any weaknesses that may be present in the track structure, making the track more susceptible to failure.”
C&NW, CA&E, MILW, CGW and IC fan
That sounds like oil unit trains on lines not previously used for unit trains breaking rails, which is what I said earlier...
M636C
M636C schlimm wrote the following post an hour ago: “Petroleum crude oil unit trains transporting heavily loaded tank cars will tend to impart higher than usual forces to the track infrastructure during their operation,” the safety board said in a report this year. “These higher forces expose any weaknesses that may be present in the track structure, making the track more susceptible to failure.” That sounds like oil unit trains on lines not previously used for unit trains breaking rails, which is what I said earlier... M636C
What you and others have said may be true, but where does the quote referring to the Canadian board say anything about it being on lines not previously used for unit trains? Didn't the derailment/explosion in the Dakotas occur on track used by unit grain trains for years? Didn't the derailment this spring on the BNSF south of E. Dubuque occur on track used by various unit trains for years?
In any case you are suggesting that unit oil trains damage track, which has been the contention of myself and others.
EuclidDave, Once again you are constructing an absurdity and attributing it to me.
Trying to reason with you is the real absurdity. You construct these fanciful visions of how physics works and then will spend weeks defending impossible positions quoting and requoting things until its so convoluted nobody can unravel it.
You are wrong. Period. Sorry. Try another approach.
Dave H. Painted side goes up. My website : wnbranch.com
schlimmIn any case you are suggesting that unit oil trains damage track, which has been the contention of myself and others.
All trains wear down (damage) track. Unit trains wear down track faster than other trains. Oil trains are unit trains. Therefore oil trains do wear down track faster than TRAINS OTHER THAN UNIT TRAINS.
About the ONLY thing that has been brought up that is factual that makes oil trains different from coal or grain trains is that they are made up of tank cars which have a more rigid structure (a thick metal tube is more rigid than a thin steel "box"). Of course that factor would also apply to unit ethanol or other liquid chemical trains.
EuclidWizlish, Who are you responding to? You appear to be quoting me, but you are actually quoting Dave Husman.
Who are you responding to? You appear to be quoting me, but you are actually quoting Dave Husman.
Fixed.
schlimm... However, if one returns to early posts, I recall some experts with credentials who seemed to think the sloshing could have a significant effect in some way making derailments more likely. Are you disputing that or just Euclid's diversion?
The relatively short answer is that we need a bit more data, for example from the Canadians who reported “Petroleum crude oil unit trains transporting heavily loaded tank cars will tend to impart higher than usual forces to the track infrastructure during their operation." In order to make that statement, they know what those forces are, what planes they act in, why their magnitude is 'higher than usual' either in force or resonance,etc. -- and they can provide us these data and, more or less immediately in so doing, end the controversy about what the supposed additional forces might be and how they're supposed to be affecting the track.
I think some component of slosh may be involved with increased possibility of oil-train derailment if 'the track [has been made] more susceptible to failure'. But I certainly don't think broken rails due purely to slosh or related effects (or other carbody motion accentuated by slosh effects) are even remotely likely. To repeat what Mr. Husman said on the morning of the 13th: "So really that is the question. Are the oil trains CAUSING the defects or is the oil train FINDING the defects? They are two different problems with two different solutions." This present discussion is a kind of third choice, where the supposed added force finds a weakness and snaps it over into a 'caused defect' when the rail concerned is under the train.
Not to put words in the Canadians' mouths, but when they said "any weaknesses" I'm reasonably sure they meant something like 'any weaknesses that would be compromised by the 'higher than usual forces' specifically, but not by ordinary trains or traffic', and not weaknesses (like, for example, many kinds of railhead or web defect) that their 'higher-than-usual' forces would be unlikely to cause to progress to critical derailment-causing failure.
Until we have the specific data about the higher forces, and what characteristics unique (or supposedly unique, perhaps) to unit oil trains are producing them, any further observations or 'theorizing' I might make would be little better than speculation. On the other hand, I can comment on aspects that likely do not cause problems, or contribute disproportionately to complex interactions.
If someone will link to the so-far-not-cited report, I will read it, see if it contains data on the specific forces and/or presumed mechanisms of action, and request information from the appropriate people or other entities if not. Better yet if someone with credentials who is following this thread does the same.
dehusman Euclid Dave, Once again you are constructing an absurdity and attributing it to me. Trying to reason with you is the real absurdity. You construct these fanciful visions of how physics works and then will spend weeks defending impossible positions quoting and requoting things until its so convoluted nobody can unravel it. You are wrong. Period. Sorry. Try another approach.
Euclid Dave, Once again you are constructing an absurdity and attributing it to me.
Been going on for years. Do you think he's going to change? IMO, NOT A CHANCE.
Norm
Wizlish schlimm ... However, if one returns to early posts, I recall some experts with credentials who seemed to think the sloshing could have a significant effect in some way making derailments more likely. Are you disputing that or just Euclid's diversion? The relatively short answer is that we need a bit more data, for example from the Canadians who reported “Petroleum crude oil unit trains transporting heavily loaded tank cars will tend to impart higher than usual forces to the track infrastructure during their operation." In order to make that statement, they know what those forces are, what planes they act in, why their magnitude is 'higher than usual' either in force or resonance,etc. -- and they can provide us these data and, more or less immediately in so doing, end the controversy about what the supposed additional forces might be and how they're supposed to be affecting the track. I think some component of slosh may be involved with increased possibility of oil-train derailment if 'the track [has been made] more susceptible to failure'. But I certainly don't think broken rails due purely to slosh or related effects (or other carbody motion accentuated by slosh effects) are even remotely likely. To repeat what Mr. Husman said on the morning of the 13th: "So really that is the question. Are the oil trains CAUSING the defects or is the oil train FINDING the defects? They are two different problems with two different solutions." This present discussion is a kind of third choice, where the supposed added force finds a weakness and snaps it over into a 'caused defect' when the rail concerned is under the train. Not to put words in the Canadians' mouths, but when they said "any weaknesses" I'm reasonably sure they meant something like 'any weaknesses that would be compromised by the 'higher than usual forces' specifically, but not by ordinary trains or traffic', and not weaknesses (like, for example, many kinds of railhead or web defect) that their 'higher-than-usual' forces would be unlikely to cause to progress to critical derailment-causing failure. Until we have the specific data about the higher forces, and what characteristics unique (or supposedly unique, perhaps) to unit oil trains are producing them, any further observations or 'theorizing' I might make would be little better than speculation. On the other hand, I can comment on aspects that likely do not cause problems, or contribute disproportionately to complex interactions. If someone will link to the so-far-not-cited report, I will read it, see if it contains data on the specific forces and/or presumed mechanisms of action, and request information from the appropriate people or other entities if not. Better yet if someone with credentials who is following this thread does the same.
schlimm ... However, if one returns to early posts, I recall some experts with credentials who seemed to think the sloshing could have a significant effect in some way making derailments more likely. Are you disputing that or just Euclid's diversion?
Your subtext is that you set yourself up as more expert than the Canadian investigators who wrote the reports referred to in the article. If the report is produced, then you "will read it, see if it contains data on the specific forces and/or presumed mechanisms of action, and request information from the appropriate people or other entities if not." I am not an expert on this and do not pretend to be. But what are your credentials to disregard the preliminary conclusions of the safety board? What are Husman's?
Just how old is Bucky that he claims to have seen a wooden gon?
Wizlish Euclid The force is a reaction to slack run-in. The force that produces the dynamic load moves forward along the horizontal axis of the tank car. When it does, the oil moves forward, and the air it displaces moves rearward. So the impact tends to cause the oil to be separated from the air in a vertical plane. Whether it actually achieves that vertical separation depends on the dynamic force generated in the impact. Then after the impact, the oil and air move back to their original positions with the air on top and oil on the bottom. During the impact, the dynamic load is applied horizontally to the forward head of the tank. During this impact, all of the oil load moves as part of the dynamic force. Every single molecule of oil moves as the oil shifts its position and separates from the air in a vertical plane. The oil molecules move at differing speeds, in different directions, and over differing distances. Once the oil and air separate vertically, every molecule of oil is stopped from moving by the blockage of the leading tank head. That abrupt stopping of the oil is where the kinetic energy that produces the dynamic load comes from. It comes from the sum total of all molecules being stopped. However, some molecules will be moving faster than others, so as they are stopped, they will contribute differing individual amounts of kinetic energy to the total dynamic load. But the point is that the entire load of oil is involved in producing the dynamic load on the leading tank head. It is not just the amount of oil that equals part or all of the air space. Slack run-in causes the relatively viscous oil to move forward and up into the void space, with the air being displaced up and back. This is a very small portion of the oil in the car,and the 'energy' involved is no more than that amount being raised against gravity the relatively small distance corresponding to the area of the tank head that originally corresponded to the void. Very simple and straightforward fluid mechanics describe how this works. There is no "vertical"separation of air and water, whatever that is, nor is there the sort of dramatic momentum transfer that would be observed of a solid object crashing into a decelerated structure. All you need to do to observe the behavior involved is to fill a transparent tube with an appropriately viscous fluid, and then slide it laterally against a stop (or tilt it a few degrees) with the end resting on an appropriately sensitive scale.
Keep in mind that the track is hardly a rigid structure, either vertically or even laterally. Repeated flexing may lead to metal fatigue. The problems we see may not have been anticipated by the HAL studies that led to the increased weight limit of 286,000#. The studies seem to have weighted the factor of economic efficiency over future track safety problems. We also have no way of knowing if track is actually maintained to the optimal levels assumed in the HAL studies.
Link to one of the Canadian TSB reports.
http://www.tsb.gc.ca/eng/rapports-reports/rail/etudes-studies/siir0501/siir0501_sec2.asp
and other more recent derailments:
http://www.tsb.gc.ca/eng/rapports-reports/rail/index.asp
schlimm Keep in mind that the track is hardly a rigid structure, either vertically or even laterally. Repeated flexing may lead to metal fatigue. The problems we see may not have been anticipated by the HAL studies that led to the increased weight limit of 286,000#. The studies seem to have weighted the factor of economic efficiency over future track safety problems. We also have no way of knowing if track is actually maintained to the optimal levels assumed in the HAL studies.
economic efficiency was balanced against track costs. Dr. Hargrove and his staff were very careful about that. If economic efficiency was paramount 315,000# would have been the choice. All the results were vetted with the Chief Engineers of the AAR members to ensure that the track maintenance assumptions were realistic. Remember that the AAR's HAL studies were initiated at the request of the Chief Engineers. If your thesis was correct there would have been an uptic in track related issues after the mid 90's instead of the continued downward trend.
BTW rail defects are primarily the result of contact stress not bending stress.
Buslist schlimm Keep in mind that the track is hardly a rigid structure, either vertically or even laterally. Repeated flexing may lead to metal fatigue. The problems we see may not have been anticipated by the HAL studies that led to the increased weight limit of 286,000#. The studies seem to have weighted the factor of economic efficiency over future track safety problems. We also have no way of knowing if track is actually maintained to the optimal levels assumed in the HAL studies. economic efficiency was balanced against track costs. Dr. Hargrove and his staff were very careful about that. All the results were vetted with the Chief Engineers of the AAR members. If your thesis was correct there would have been an uptake in track related issues after the mid 90's instead of the continued downward trend. BTW rail defects are primarily the result of contact stress not bending stress.
economic efficiency was balanced against track costs. Dr. Hargrove and his staff were very careful about that. All the results were vetted with the Chief Engineers of the AAR members. If your thesis was correct there would have been an uptake in track related issues after the mid 90's instead of the continued downward trend.
My hunch (hardly a thesis) has been that the problems are unique to oil unit trains, not merely 286K unit trains of coal or grain. But 286K clearly is a problem, if you look at the Canadian studies. Having AAR involved in the studies for HAL relies too much on the rails setting the rules and regulating themselves. And the problems would not show up immediately in the 1990s; it takes time as more and more 286K cars and unit trains have been introduced. Repetition. And track is particularly susceptible to breakage in cold weather and high-impact wheels (flattened wheels on heavy cars) passage.
schlimm Link to one of the Canadian TSB reports. http://www.tsb.gc.ca/eng/rapports-reports/rail/etudes-studies/siir0501/siir0501_sec2.asp and other more recent derailments: http://www.tsb.gc.ca/eng/rapports-reports/rail/index.asp
The first report is relavant to this discussion. The second item is an index to various specific accident reports, so is of little if any use.
The first report simply documents what any track man can tell you from experience, unit trains are harder on track than other trains. It does not address unit OIL trains.
The report is about secondary lines that handle reasonably heavy traffic with some part of that volume being in unit trains.
I summarizes several unit train derailments. Virtually all of them were due to broken rails due to internal defects, broken rails at joints, or broken joint bars. Rail weight was 115-100 pounds. Not mentioned was age of the rail, most of which I suspect was at least 50 years and the 100 pound could be 70 or 80 years old. Since these were secondary lines, tie and ballast condition could have been marginal. Marginal support tends to increase dynamic loading due to bounce and roll. Unit trains are worse since each car will behave the same way, so the train repeatedly stresses the same points.
In short, it says unit trains tend to find the internal flaws in (old, light) rail and weak spots in weak track. It says nothing about oil trains being any more likely to do so than other types of unit train. The most likely reasons are: not enough data to support any conclusion, and/or report was done before the oil train question was asked.
In short, well worth the read if you have an interest in unit trains on secondary main line track.
Mac
Perhaps you need to read more carefully? At the beginning, the ages and weights of the rail in the eight accidents are clearly given. So your summary is inaccurate and misleading.
The six CPR cases are on a parallel secondary main; the two CNR cases are feeders.
schlimm My hunch (hardly a thesis) has been that the problems are unique to oil unit trains, not merely 286K unit trains of coal or grain. But 286K clearly is a problem, if you look at the Canadian studies. Having AAR involved in the studies for HAL relies too much on the rails setting the rules and regulating themselves. And the problems would not show up immediately in the 1990s; it takes time as more and more 286K cars and unit trains have been introduced. Repetition. And track is particularly susceptible to breakage in cold weather and high-impact wheels (flattened wheels on heavy cars) passage.
Of course problems wouldn't show up immediately but the decision was based on 7 years of 315 operation on the HAL test track, with track deterioration carefully monitored and compared to previous operation with 263 traffic. And if of course problems came up later the 50% reduction in track related derailments between 2006 and 2014 (AAR data) is just a fluke!
High impact wheels have deminished significantly with the roll out of the WILD networks. There are really few cold weather broken rail derailments, any involving CBR?
The whole argument about loads from crude oil tanks could be solved for about $200,000. All you need to do is run a loaded tank through the Chapter 11/M976 test tracks (OMG the industry regulating itself!!) using a stock IWS at Pueblo and compare its performance to a myrid of known vehicles.
I think we should run an experiment with unit ethenol (less viscuous) and unit corn syrup (more vicuous) and see how badly the track is damaged.
Bottom line is I don't know , I doubt that the unit crude trains are creating unique track stress but I cannot prove it, maybe someone will?
Randy
EuclidInvestigators and rail safety experts are looking at how the weight and movements of oil trains may be causing higher than expected track failures.”
Perhaps you can explain why a 286,000 lb tank car of oil would be any different in it's interaction with the rails than any other 286,000 lb tank car of similar viscosity and product weight.
As usual, you are beating the dead horse to death. Is your agenda to get oil trains off the rails?
Norm48327 Euclid Investigators and rail safety experts are looking at how the weight and movements of oil trains may be causing higher than expected track failures.” Perhaps you can explain why a 286,000 lb tank car of oil would be any different in it's interaction with the rails than any other 286,000 lb tank car of similar viscosity and product weight. As usual, you are beating the dead horse to death. Is your agenda to get oil trains off the rails?
Euclid Investigators and rail safety experts are looking at how the weight and movements of oil trains may be causing higher than expected track failures.”
T
Buslist schlimm My hunch (hardly a thesis) has been that the problems are unique to oil unit trains, not merely 286K unit trains of coal or grain. But 286K clearly is a problem, if you look at the Canadian studies. Having AAR involved in the studies for HAL relies too much on the rails setting the rules and regulating themselves. And the problems would not show up immediately in the 1990s; it takes time as more and more 286K cars and unit trains have been introduced. Repetition. And track is particularly susceptible to breakage in cold weather and high-impact wheels (flattened wheels on heavy cars) passage. So the AAR's involvement smacks of the Railroads self regulation, not of them maximizing the return on their investment , guess you want to bring back the first USRA. Of course problems wouldn't show up immediately but the decision was based on 7 years of 315 operation on the HAL test track, with track deterioration carefully monitored and compared to previous operation with 263 traffic. And if of course problems came up later the 50% reduction in track related derailments between 2006 and 2014 (AAR data) is just a fluke! High impact wheels have deminished significantly with the roll out of the WILD networks. There are really few cold weather broken rail derailments, any involving CBR? The whole argument about loads from crude oil tanks could be solved for about $200,000. All you need to do is run a loaded tank through the Chapter 11/M976 test tracks (OMG the industry regulating itself!!) using a stock IWS at Pueblo and compare its performance to a myrid of known vehicles.
So the AAR's involvement smacks of the Railroads self regulation, not of them maximizing the return on their investment , guess you want to bring back the first USRA.
If the derailments showed up after oil unit trains became common, that is not likely to be a coincidence. As to cold weather and track vulnerability (a correlation seem by actual experts), let's see what happens this winter.
Euclid Wizlish Euclid The force is a reaction to slack run-in. The force that produces the dynamic load moves forward along the horizontal axis of the tank car. When it does, the oil moves forward, and the air it displaces moves rearward. So the impact tends to cause the oil to be separated from the air in a vertical plane. Whether it actually achieves that vertical separation depends on the dynamic force generated in the impact. Then after the impact, the oil and air move back to their original positions with the air on top and oil on the bottom. During the impact, the dynamic load is applied horizontally to the forward head of the tank. During this impact, all of the oil load moves as part of the dynamic force. Every single molecule of oil moves as the oil shifts its position and separates from the air in a vertical plane. The oil molecules move at differing speeds, in different directions, and over differing distances. Once the oil and air separate vertically, every molecule of oil is stopped from moving by the blockage of the leading tank head. That abrupt stopping of the oil is where the kinetic energy that produces the dynamic load comes from. It comes from the sum total of all molecules being stopped. However, some molecules will be moving faster than others, so as they are stopped, they will contribute differing individual amounts of kinetic energy to the total dynamic load. But the point is that the entire load of oil is involved in producing the dynamic load on the leading tank head. It is not just the amount of oil that equals part or all of the air space. Slack run-in causes the relatively viscous oil to move forward and up into the void space, with the air being displaced up and back. This is a very small portion of the oil in the car,and the 'energy' involved is no more than that amount being raised against gravity the relatively small distance corresponding to the area of the tank head that originally corresponded to the void. Very simple and straightforward fluid mechanics describe how this works. There is no "vertical"separation of air and water, whatever that is, nor is there the sort of dramatic momentum transfer that would be observed of a solid object crashing into a decelerated structure. All you need to do to observe the behavior involved is to fill a transparent tube with an appropriately viscous fluid, and then slide it laterally against a stop (or tilt it a few degrees) with the end resting on an appropriately sensitive scale. Wizlish, The vertical separation of the oil from the air simply means the oil has moved forward as far as possible. When that happens, the trailing surface of the oil is vertical. In normal running the separation between the oil and air is horizontal. I am describing a process of load shifting due to extreme slack run-in such as the degree of run-in that might stand a car up or buckle the train sideways. Perhaps the load shifting of oil can contribute an additional destructive element sufficient to cause a derailment in cases of hard run-in that would that would be insufficient to cause a derailment if there was no load shifting. What you describe with your glass tube experiment is exactly what I have described. The only difference is that you use gentle sounding terms of a desktop experiments to sound like the effect will not be violent. I have not claimed that this does or can happen. Others have raised the same question. The FRA raised the question. The only people that I know of that have asserted that it cannot happen is you and Dave Husman. Maybe you or Dave should let the FRA know that sloshing cannot cause a derailment, so they don’t waste a lot of time investigating it.
Euclid, with regard to the first part where you are quoted, "The oil molecules move at differing speeds, in different directions, and over differing distances." You don't specifically make reference, but these are some of the things that happen in wave movement, which best describes what is happening in the decelerating tank car. In a wave the molecules move by bumping into each other, rather than moving long distances. A tank car with 3% air space would have about 8" of headspace (using an online secant calculator). Molecules in a liquid wave travel in a circular motion, the maximum radius of the circle (a molecule at the top surface) would be equal to the wave amplitude. The circular movement radius decreases with depth. So while all the molecules in the tank car are moving, the maximum distance would be 8", and the average distance may be half that. The problem I have is when you say "But the point is that the entire load of oil is involved in producing the dynamic load on the leading tank head. It is not just the amount of oil that equals part or all of the air space." If a tank car was totally fluid filled, there would be no extra fluid kinetic influence. With 3% air space, the wave motion is limited by this amplitude, so the obvious deduction is that the extra kinetic energy is porportional to the amount of airspace. So it is misleading to say "the entire load of oil is involved in producing the dynamic load", when it is actually just proportional to the amount of headspace.
I agree with Wizlish. In your reply you seem to have some semantics differences with him, and you apparently thought his use of the term "appropriately sensitive scale" was to downplay your more violent motion thesis. I don't see anywhere in his reply where he "asserted that it cannot happen". The FRA has to explore all the possibilities, and they should run tests to see what the effects of sloshing are. If it is that worrisome, I wonder why they have not done that yet.
Midland Mike: Thanks for the cogent application of wave motion to an oil tank car by an expert who is clear about his background.
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