schlimm It wasn't an insult. It was sarcasm. i guess I should have labeled it as such to avoid confusion.
It wasn't an insult. It was sarcasm. i guess I should have labeled it as such to avoid confusion.
SO, no on topic response.
Thank you and have a wonderful night, Professor.
It's been fun. But it isn't much fun anymore. Signing off for now.
The opinions expressed here represent my own and not those of my employer, any other railroad, company, or person.t fun any
Randy StahlHere's the killer to your plan, The "unbreakable" drawbar means that you must also have an unbreakable car. While I'm sure this is possible what you will end up with is a car that weighs 80-90 tons EMPTY.
Randy,
I don’t expect this proposal to require excessively heavy tank cars. The point of the solid drawbars is to keep the cars coupled during a derailment as they are placed under tension by selective braking and power application to prevent them from jackknifing and piling up. That is a two-part objective. The larger part of that objective is accomplished by eliminating the knuckles and related features that can break and disengage from twisting and bending as well as pure pulling stress. There will be a lot of that twisting and bending coupler stress because the cars will be running on the ground, tearing up track and plowing ballast, so what is needed is coupler integrity that goes beyond the abilities of tightlock or shelf couplers.
The second part of the objective is the capability of the drawbars to handle the tensile pull of the selective braking and power application from the moment the derailment begins to when the train stops moving. I don’t know whether that would subject couplers to a higher than usual tensile pull. If it does, it would require heavier drawbars and possibly more weight added to reinforce the tank. When I mentioned center sills, I am not necessarily suggesting full, independent center sills with the tank sitting on top of them. I am only referring to the structural features integrated with the tank that reinforces the pulling line of the car. It may only be a thickening of steel along the bottom. They simply replicate the purpose of a center sill.
But, as I say, this may or may not be necessary, and in any case, I don’t expect it to add so much weight that it makes the car too heavy to be practical. The strengthening that the regulators are planning will also add weight to the cars, so heavier cars are inevitable. Somewhere I read that they are planning to increase the capacity to offset the weight penalty. It would be interesting to hear how they will accomplish that.
But these extra strong drawbars are just one feature of a system of features that are intended to work together. Probably the least important feature is item #3 in my opening description. If the selective braking and power application do their job of keeping the derailing cars stretched, there would be no need for drawbars and buffers working together to resist jackknifing. And the buffer structure would also add considerable weight. So, I would say that item #3 might be omitted from the list of features.
Overmod,
Thanks for your comments. Like you, I am interested in learning exactly how the new tank cars will be made safer, and how safe they will be. Seat belts made cars safer, but air bags make them even safer. Is this proposed tank car improvement intended to solve the problem or just be an incremental improvement?
Maybe somebody can post a link to a reference showing exactly what it planned to be improved with the new tank car safety standards. I would like to know how much safer they will be. For instance, I would like to know it this: In the case of the Casselton wreck, if that train was made up of the new and safer generation of tank cars, would there have been a fire? This is an engineering question, and reinforcing the tank cars is an engineering project, so the answer to my question about how the improved tank cars would have performed in the Casselton wreck ought to have a specific answer. It is an obvious question in the context of the Casselton wreck and the proposal to prevent such an occurrence in the future.
Regarding the other proposal to prevent fouling collisions between passing trains: Certainly that type of collision has the greatest potential for violence because of the combined speed of the two trains, so it would help. However, the potential for it only exists during the passing phase, and that will be a very small percentage of the entire route traveled. So stopping one train during a passing meet will add safety during that time, but the entire rest of the route will provide constant opportunity for derailments. And any derailment, although being perhaps less violent than a fouling collision, will nevertheless provide plenty of opportunity for tank breaching and a resulting fire.
Randy, Overmod, and BaltACD:
Regarding your comments about excessive car weight on page 1, I don’t expect this proposal to result in excessively heavy tank cars. The point of the solid drawbars is to keep the cars coupled during a derailment as they are placed under tension by selective braking and power application to prevent them from jackknifing and piling up. That is a two-part objective.
The larger part of that objective is accomplished by eliminating the knuckles and related features that can break and disengage from twisting and bending as well as pure pulling stress. There will be a lot of that twisting and bending coupler stress because the cars will be running on the ground, tearing up track and plowing ballast, so what is needed is coupler integrity that goes beyond the abilities of tightlock or shelf couplers.
Like you, I am interested in learning exactly how the new tank cars will be made safer, and how safe they will be. Seat belts made cars safer, but air bags make them even safer. Is this proposed tank car improvement intended to solve the problem or just be an incremental improvement?
Anything made by man can break - rail, wheel, coupler, knuckle, drawbar, side sheet, truck side frame, roller bearing.
Anything formed by Nature can be reformed by Nature, generally with catastrophic immediate results.
Without the commodities carried by all the forms of transportation all the NIMBY BANANA's would die of starvation and freeze to death.
Safety has never been absolute in the history of humanity, and never will be.
Never too old to have a happy childhood!
The really unique aspect of this proposal as outlined in the original post is a specialized braking system that does NOT go into emergency when the first air hoses separate at the beginning of a derailment.
I doubt that anybody has ever considered this idea before. I think that derailments are regarded as something that just happens. You do all that is possible to prevent them, but I have never heard of trying to control them once they begin. Controlling them would seem to be impossible.
Controlling derailments after they begin, as I am proposing, would only be possible with the advent of ECP brakes, and even with that, the idea that I am proposing would not be obvious. It would be a whole new category of braking phase instead of the traditional “emergency” phase that is triggered during a derailment. It could be called the “derailment” phase of braking. It would be fully automatic just like the airbag system in cars is automatic.
The derailment phase brake system would sense a derailment by proximity detectors and motion analyzers. It would detect a truck derailing the instant it happens, and begin a braking protocol based on train weight, distribution of the weight, number of cars, speed, location of derailment site in the train, and the location of the train on the line. Then it would control braking independently to the cars ahead of the derailment and the cars behind it.
It would apply brakes on the cars in each section at exactly the same time. There would be no sequential propagation of braking through the length of the train. With the solid drawbars, there would be no slack run-in or run-out to interfere with the control of the derailing train. The control would have to be wireless in case the cables get broken during the derailing process.
EuclidI doubt that anybody has ever considered this idea before. I think that derailments are regarded as something that just happens. You do all that is possible to prevent them, but I have never heard of trying to control them once they begin. Controlling them would seem to be impossible.
Yes, Bucky, I'm sure people have considered the idea already. Especially in the age of ECP.
Deva vu all over again.
Norm
Euclid Maybe somebody can post a link to a reference showing exactly what it planned to be improved with the new tank car safety standards. I would like to know how much safer they will be. For instance, I would like to know it this: In the case of the Casselton wreck, if that train was made up of the new and safer generation of tank cars, would there have been a fire? This is an engineering question, and reinforcing the tank cars is an engineering project, so the answer to my question about how the improved tank cars would have performed in the Casselton wreck ought to have a specific answer. It is an obvious question in the context of the Casselton wreck and the proposal to prevent such an occurrence in the future.
I believe the improvements include increased shell thickness and shields built into the ends, similar to what is standard now for flammable gas cars. In addition there would be shields for the bottom outlets and dome valves to reduce shearing.
As far as whether they would have been punctured, that would take a lot more information on what the speeds were, what the angle of impact was, what parts of which cars struck what part of the tank cars. For example a hopper or tank car shell striking the tank car shell, probably no. A coupler striking the lower end probably no. A couple striking the side of a tank car, possibly.
TIH/PIH cars are arguably the heaviest car designs out there and even they get punctured under the right circumstances (the UP, AAR and chemical shippers are in the final stages of testing the next generation TIH/PIH car, its been in the works for a while).
The chances would be lower in the Casselton incident, Lac Megantic would have breached less, but still would have breached some (even battleship armor can be pierced by a piece of metal with enough weight and velocity).
Dave H. Painted side goes up. My website : wnbranch.com
There will still be slack action in loaded trains. Liquids have slosh. If all the drawbars are solid, the engine might get a real good wallop if they have to stop quick.
When the air dumps on a train, the PCS cuts power at the locomotive as well. The engines go to idle. At that point, you bail off and enjoy the ride.
Wireless controls have issues of their own. Maybe use it as a backup to the wired ECP brake system.
Mike WSOR engineer | HO scale since 1988 | Visit our club www.WCGandyDancers.com
WSOR 3801,
The air won’t dump on this train. It does not have to because no quick action feature of air is needed to propagate the response through the length of the train. The EPC control will set all brakes simultaneously. The oil in the tanks will simply swell to the front of all tanks simultaneously in proportion to the brake force. It won’t run in like slack. The engines may or may not go to idle depending on what the automatic system needs to best mitigate the derailment process.
One has to figure where the "brains' of this proposal will reside. With PTC the engines need to know the location of the train and its tonnage and length. The consist (standing order of the cars) would also need to be know to the train (not required for PTC). If the brains is in the engine then you keep the information central and have to communicate the commands to the cars. If the brains are in the cars you have to communicate (and remember) the train and position information to the cars and be able to designate one car to be the leader and command the rest of the brake system. With small air powered turbine generators (same thing that's in EOT's), powering all the electronics could be feasible. The question is can the system figure all this out quick enough and communicate it soon enough to make a difference.
Also since PTC is not universal, what do you do outside of PTC when the consist, location and train characteristics are not necessarily available?
One question on all these high strength drawbars. If several cars derail and turnover (broken rail on a fill), what keeps the drawbars from rolling the rest of the train over?
Dave,
I had not considered your point about the drawbars being able to transmit upset from one car to the next. Somehow that would have to be addressed. I recall that there was a tank train derailment maybe ten years ago in western Minnesota. As I recall, all or nearly all of the train tipped over. And apparently it was not moving very fast because all the cars were laid out in a perfectly straight line, on their sides along the track.
In the concept that I am describing, even though there would be a lot of control directed to the derailment process, there would still be plenty of opportunity for chaos. But the hope would be that the drawbars hold it all together and keep it stretched out. But even in that arrangement, there would still be rails flying around, cars hopping over trucks, etc. Cars could upset by all of the chaos going on underneath them.
I am not sure how all of the control system and the brains should be set up. There would be plenty of engineering to do to get that developed.
Euclid In the concept that I am describing, even though there would be a lot of control directed to the derailment process, there would still be plenty of opportunity for chaos. But the hope would be that the drawbars hold it all together and keep it stretched out. But even in that arrangement, there would still be rails flying around, cars hopping over trucks, etc. Cars could upset by all of the chaos going on underneath them.
A lot of this seems to assume that that the derailed cars will continue upright and parallel in line. What happens when the first cars derails, digs in and stops with 8000 tons of train behind it still moving? In a conventional train the cars accordion with each car absorbing part of the energy and burning off the momentum of the train. With the drawbars preventing that ALL of the energy will be focused onto the first derailed car. That first car is going to pop or the cars behind it are going to start catastrophically failing. The bolts holding the draft gear in will start shearing off the drawbars will rip the pins out of the housings the center sills will collapse and bust the tanks of the center sill. Something's going to give. Metal has shear and tensile strengths and if you exceed it, it breaks. So you are designing it, what part do you want to break? If you leave the choice up to the derailment, you won't be happy with the outcome.
Unless one is a structural engineer with experience in tank design, I would leave it to people who have studied the problem in depth, visited the sites of some of the recent "incidents," have the state-of-the-art computer facilities to get meaningful results from measured data, have have the intelligence to know when measured data is false because of an equipment malfunction or when computer results are a screwy, and then produce the safe tankcar. I think this is what is in progress, and I think this is what I expect to increase safety in the time required to replace the present non-complying tankcar fleeet.
You wondered how they might increase capacity. Possibly a circular cross-section is not the safest, and somethin else can increase both safety and capacity?
It's nice to see some thought about this problem. I have some comments...
Euclid1) Cars semi-permanently coupled with extra strength solid drawbars and continuous extra heavy car center sills.
This is a tough one. The tank cars don't have center sills now, just stub sills weld to each end. The tank itself is the center sill. Are you proposing adding a center sill to increase buff/draft strenght? This adds weight at the expense of lading
Euclid2) Revised tank car design for puncture resistance, stronger center sill elements, stronger drawbar connections, and limited pivot trucks with safety chains.
Are we talking about drawbars in lieu of couplers? The existing shelf couplers do a pretty good job of staying with each other during a wreck. If beef up the draft arrangement, what's the next weakest link? Center sill/tank buckling? The energy has to go somewhere. (BTW solid drawbars tend to cause derailments from track cross-level variations. It's why those double 89' flat cars have couplers and not solid drawbars)
Euclid3) Car buffer system integrated with the drawbars that resist car jackknifing leading to an accordion pileup.
If the train can't "accordion" where does the energy go? The zig-zag pile-up might not be a bad thing from a derailment energy management system point of view.
Euclid4) Electronically Controlled Pneumatic brakes (ECP) with a “smart emergency” feature that can detect a derailment and react to the derailment in a way that mitigates the risk of an accordion or similar pileup of cars.
Euclid5) Cars equipped with sensors to monitor temperature of running components, vibration, sound, motion, etc., and connected permanently by continuous electrical cabling to transmit the data to a control center in the locomotive.
Like this, but bring money! I think we are headed there, but not for a few decades. I doubt a wired data trainline is the way, though.
There is just so much energy in a mainline, track speed derailment the trick is to figure out what stuff gets broken and how it breaks to dissipate the energy. Secondly, while this is going on, how do you protect the lading? Thirdly, if the tanks are breached, how to you prevent a BLEVE?
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
Don,
Thanks for your comments and perspective. I am working on a response to what Dave said, and some of it will also address your comments and concerns about drawbars, energy dissipation, etc.
I agree that this will cost a lot of money, but a lot is at stake in losing the oil traffic business. I believe this oil train problem is a huge challenge, and it calls for a proportionate response. Part of that response must be to convince the public that the industry is working hard to solve the problem. That part is actually a marketing endeavor. I think that is the missing ingredient in the response to strengthen tank cars. That alone is an engineering response, but I don’t think it is going to satisfy the public outcry, and ultimately, the public is in the driver’s seat.
To incorporate the marketing component of the industry response, what is needed is a sexy new train. It would be a “smart oil train”. It should look different, look advanced, have lots of electronics and computer control. It should look good, have an exceptionally nice color scheme, and style. It should look like clean energy rather than crude oil.
It should be unveiled and presented to the public as though it were a brand new sports car. Then it should be explained in detail. Even before it is perfected it could be mocked up and presented as a concept train that will make everybody safe.
That is why I want a "Pullman of Freight Transportation, Key Transportation," with a sexy name and evocation of the really unexcelled safety of Pullman passenger transportation --once they made steel cars universal. Note that oil trucks these days no longer have round tanks, they are oval. Possibly with the desire for increased capacity, the newest and safest tankcars will also have oval tanks, but long dimension vertical to take advantage of clearances available even on the more restricted existing freight routes.
...... or you could just use the flammable gas design in service now as a basis. They are proven designs, heavier construction, available off the shelf and a good safety record.
If somebody gave you $100,000,000 right now and said go build one, it would be 5, closer to 10 years (or more with the technology) before is would be certified for use. Then the companies would have to buy them, so you might get a significant penetration into the fleet 20-25 years from now.
Since the companies can't wait that long (the existing fleet will be reaching the end of its lifespan) they will probably replace the current cars with the improved conventional design variants anyway, which will make them reluctant to buy the new cars since the improved designs will most likely be be sufficient.
dehusmanit would be 5, closer to 10 years (or more with the technology) before is would be certified for use. Then the companies would have to buy them, so you might get a significant penetration into the fleet 20-25 years from now.
The revolutionary Airbus A380 went into design in 1997, test flights 2005, certification 2006-7, service entry Oct. 2007. Rather a lot more complicated and expensive than a tank car, yet 10 years from design to service, with 122 built so far. Is it just possible that a breakthrough tank car design might be somewhat quicker?
C&NW, CA&E, MILW, CGW and IC fan
dehusmanWhat happens when the first cars derails, digs in and stops with 8000 tons of train behind it still moving?
The air brakes are what stop the 8000 tons behind still moving behind the derailment. Certainly, the accordion action and crushing of cars in a derailment does absorb energy, as you say. However, this is not desirable, nor is it an intentional part of the design as it is in automotive design, for example, where the crushing of the front of the car absorbs energy. That is intentional design to save the life of the driver. When freight cars crush in a derailment, nothing good results from it. It destroys equipment and cargo, ruptures tank cars, and threatens lives nearby.
So my point of this safe oil train concept is to avoid that. In a conventional train, air brakes stop the cars behind the derailment. They also stop the cars ahead of the derailment. But they do this by full emergency application in all cars, ahead of and behind the derailment. The response propagates through the cars toward the front and back of the train, starting from the derailment point. It is an automatic response that cannot prevented or overridden.
In my concept, the brake response is also automatic, but it is a “smart” response. It senses the derailment and varies the brake response according to what is needed. For example, it can apply any amount of braking to any car, completely independent of all other cars. In the case of a derailment, it senses the derailment, and applies braking to the cars behind the derailment. Those brakes are applied simultaneously and there is no slack action. It also applies brakes to the cars ahead of the derailment, but not as hard as the brakes are applied behind the derailment.
This difference in braking on both sides of the derailment creates tension as the inertia of the leading cars wants to run away from the trailing cars holding back with their heavier braking. This smart system will know just how much this braking difference can be maximized without pulling the train in two.
The resulting tension is the greatest on the cars ahead of the derailment and closest to the derailment site. If the cars in the derailing process can stay coupled together, this tension will extend right into the derailed cars while the train is still moving. If the derailed cars stay coupled, it makes no difference what happens to them. They can lose their trucks, tip over, snag rail, plow ballast, rip up ties, tear out crossings, and whatever. But if they stay coupled, eventually they will simply stop because of the braking drag on the cars behind the derailment. That is the desired outcome.
The point is that there is no heap of cars created with car after car being jammed into it by the string of trailing cars. That effect will rupture tank cars no matter how much armoring is added to the tanks.
The entire plan hinges on the cars derailing and remaining upright, in line and on the track structure with the trucks under them.
Everybody loves an optimist.
dehusmanThe entire plan hinges on the cars derailing and remaining upright, in line and on the track structure with the trucks under them.
It does no such thing. It depends only on the cars remaining coupled together. If they do that, they will stay relatively in line and on the roadbed. They don't need the trucks under them. They don't need to be upright.
The only purpose is to prevent the cars from piling up into a heap.
So if a car stops dead in its tracks (literally), all the other cars are going to be able to stop behind it with this braking system?
There's not a braking system in existence (or otherwise in the works) that can accomplish that.
Stuff will come apart and break (including the car frames). The cars will "accordion." Unless the tanks are made of some material we haven't heard of, they may well be punctured by trucks, trackside structures, or those unbreakable drawbars.
In other words, very much like what happens now.
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Ok, but I would think if it derailed on a sharp curve (Lac Megantic), poor track (La Megantic), around a grade crossing (Lac Megantic), was hit in the side by another object (Casselton) or derailed on a bridge where there were no shoudlers (CSX Philadelphia) you would have a problem. As long as you think an oil train will never derail under those circumstances, in those places, I'd say your assumptions are solid.
Riddle me this.
When the train derails its a pretty good bet that every axle that passes over the point of derailment will also derail and the main track will be torn up (or be plowed up) from the point of derailment to the point the first derailed car comes to a stop. How does your braking algorithm work with a large part of the train bumping along the ties?
I have been involved with too many derailments to expect the optimal outcome to be the typical outcome.
tree68So if a car stops dead in its tracks (literally), all the other cars are going to be able to stop behind it with this braking system?
No car will stop dead in its tracks. The never do unless they hit something more massive than the car; or hit something moving in the opposite direction, like another train. Then maybe the car would completely disintegrate, thus stopping dead in its tracks. All my brake concept does is control the braking on the cars ahead of the derailment rather than let them dynamite into emergency as is normally the case.
Euclid No car will stop dead in its tracks. The never do unless they hit something more massive than the car; or hit something moving in the opposite direction, like another train. Then maybe the car would completely disintegrate, thus stopping dead in its tracks.
No car will stop dead in its tracks. The never do unless they hit something more massive than the car; or hit something moving in the opposite direction, like another train. Then maybe the car would completely disintegrate, thus stopping dead in its tracks.
Ignoring the fact that trains hit massive things, cars get wedged sideways in things, etc., it doesn't take the car to stop, all it takes is a large difference in deceleration rates. Trust me, when the trucks start coming apart and gravity drives the broken trucks into the roadbed, the coefficient of friction of plowing up crossties is waaaaaaay higher than anything your brake system will be doing. The derailed car will be decelerating faster than the cars behind it. That differential in the deceleration rate causes things to go sideways. If you assume it won't happen, you will be disappointed.
All my brake concept does is control the braking on the cars ahead of the derailment rather than let them dynamite into emergency as is normally the case.
dehusmanAll my brake concept does is control the braking on the cars ahead of the derailment rather than let them dynamite into emergency as is normally the case. ..... and remind me why that is a bad thing.
It is a bad thing because the head end braking often causes it to decelerate faster than the hind end. So as the cars derail, they get shoved into a jackknifing condition by the trailing cars pressing ahead against the higher resistance of the leading cars. The best you can do is pull on the head end with the power, but the braking of the head end can offset that pulling power. And if you pull too hard, the head end can break in two. So the effect is limited. This is why it is better to control the braking ahead of the derailment rather than to let it dynamite into emergency.
Regarding your other point where you say, “Trust me, when the trucks start coming apart and gravity drives the broken trucks into the roadbed, the coefficient of friction of plowing up crossties is waaaaaaay higher than anything your brake system will be doing.”
Until you get a lot of cars on the ground, the coefficient of friction of plowing up the crossties is minuscule compared to the inertia of the rolling train. Holding back on the brakes for the leading cars retains their inertia for the purpose of pulling on the derailing cars. Heavy braking on the trailing cars removes their inertia so they cannot push into the derailment and start jackknifing cars. In addition to the pull of the head end cars due to their own momentum, power can also be applied. This would be particularly necessary where the derailment begins close to the head end, leaving too few cars ahead of the derailment to pull into the derailment with their own inertia.
The derailing cars that are plowing up ballast will be also losing their momentum just as they would with braking. So if you were to get say 15 of them on the ground, they would start to exercise a retarding effect on the derailed string of cars that would create resistance to the pull of the head end into the first cars in the derailment. That retarding effect of the derailed cars would blend with the retarding effect of the braking on the cars behind the derailment that are still running on the rails.
In other words, as the string of cars on the ground gets longer, yes its resistance can start to rival the resistance produced by the brakes on the trailing cars still on the rails. However, the resistance of those cars on the rails becomes less needed because it is replaced by the resistance of the cars dragging on the ground.
Regarding you points about other types of derailments not being addressed: I agree that this system will not work the same way every time or even be successful every time. It won’t help at all in head on or rear end collisions. It won’t work in a sideswipe at entering or leaving a passing siding. It would not have worked at Casselton because the engine of the oil train hit the derailed grain car. With the engine involved in the wreck, the derailment began right at the head end, so there would be no way for the leading part of the train to pull on the derailment. It would not work with a derailment on a bridge where the derailed train could fall off and drop into a ravine.
So for at least two of the three derailment/fire incidents of the recent past, your proposed system would have had no effect whatsoever. And it's unknown at this point in time what caused the Aliceville incident.
Given that an emergency application applies the maximum possible braking force to all the cars, and that while not instantaneous, an emergency application still transmits through the train very quickly (each car also dumps the brake line, speeding the process), any other sort of brake sensing and application would have little additional effect.
Virtually any catastrophic failure (wheel, truck, track structure) is going to have an immediate effect on the car involved, and very likely at least one of the adjacent cars. And they will almost immediately dig in, arresting their forward motion.
Even if it were possible to sense the situation and cause the locomotive to advance the throttle, the response time of the prime mover won't be fast enough to keep the slack stretched. And if the locomotive is already in notch eight, there is no acceleration to be had.
If the locomotives are in dynamics, there is about a ten second period required to go from dynamics to power, and by then things are pretty well piled up.
u can be sure that the federal test center in I believe it is pueblo Arizona is testing new improved designes all the time. they can make a cask to contain radioactive material to survive a direct hit from a locomotive. the question is always about cost. and also weight. it must work on both levels to get built and bought.
rbandr,
A tank car that is as invincible as a nuclear cask is indeed what is needed. That is a container where breaching is completely unacceptable. It would be interesting to know how thick tank car walls would have to be in order to achieve that standard. I doubt that the planned strengthening standard will come close to the reliability of a nuclear cask. But it is not an engineering problem. It is an economic problem. Nuclear waste is handled in small quantities and the cost for absolute safety must be borne. But if oil tank cars are too strong, they will price the oil out of the market, so it will have to be left in the ground.
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