Interesting story in the LA Times from last week..
http://www.latimes.com/nation/la-na-crude-train-safety-20151007-story.html
Not so sure the oil trains are the sole cause of track issues, unless it's just the increase in traffic they represent.
I'm no expert on the relative weights of the various types of unit train traffic - coal, ethanol, etc. If the oil traffic is on routes not used to the weight, that could be a factor.
A hundred cars continuousy hitting a potential defect might be like bending a wire back and forth. Eventually it will break. Manifests might not have the same effect.
I'd have to believe that the reason the oil trains are getting the attention is that they go boom. An equivalent grain train derailment doesn't garner the same national news lead as something that explodes.
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...
"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.”
Rick Inclima, safety director at the Brotherhood of Maintenance of Way Employees, also said that oil trains could be creating unique stresses on the track. “You can certainly get some rhythmic forces in ... oil trains that you might not see on a mixed freight train with cars of different sizes, weights and commodities,” he said."
C&NW, CA&E, MILW, CGW and IC fan
I'm not sure that we have seen enough oil train derailments to really concretely identify if they are causing any track failures that other train types are not. This may be a case of insufficient data.
Coal trains are just as heavy, and travel at about the same speeds, but they do not slosh.
NorthWest I'm not sure that we have seen enough oil train derailments to really concretely identify if they are causing any track failures that other train types are not. This may be a case of insufficient data. Coal trains are just as heavy, and travel at about the same speeds, but they do not slosh.
Maybe not, but the rate from derailments is double that of other cargos. Sure sounds like something differs.
As always, statistics may not paint a true picture. Rather than compare unit oil train derailments against all freight traffic, a more reliable comparison would be to compare them against other types of unit trains. I didn't see any indication that main line and yard derailments had been separated out, and by their nature unit trains tend to avoid the ministrations of intermediate yards.
I suspect what we are really seeing is that Oil Trains are being operated on many lines that were never constructed or maintained as 'heavy haul' lines. No matter what commodity would be handled in unit trains with 286K per car loads would stress the track structure beyond it's limits unless the track had had a sub-grade up rebuilding to handle these kinds of loads.
With the oil originating in the Dakota's, Alberta and Manitoba is suspect most of the branch line mileage was constructed for it's 'Granger' use in supporting local agriculture. While the lines may have been upgraded with newer rail and tie projects, I suspect they did not receive a sub-grade up rebuilding.
Never too old to have a happy childhood!
I am suspect of a lot of these numbers. Yes oil trains are heavy, yes the cars are rigid, yes unit trains are harder on track than a mixed freight train. Yes metal becomes more brittle the colder it gets. None of these are news flashes. The question is, is that significant?
I am also struggling with the "oil trains are breaking the rail" argument. I don't see where, if you actually examine the details, the latest two findings support that conclusion.
In one case there was a defect in the rail, which the NTSB says was overlooked for 2 years. That's not an oil train problem, the oil train didn't "break" the rail, it finally failed under the oil train. The rail was going to break in any case (except if it had been repaired). In the other case the rail actually broke previously and what broke under the oil train was a temporary repair. In both cases it really wasn't the oil train that was the root cause of the defect. In both cases there was a previous defect that went uncorrected or wasn't sufficiently corrected and the oil train, probably the heaviest train on the route, found the weak spot. Pretty much the heaviest train is always going to find the weak spot, its kinda obvious.
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.
Dave H. Painted side goes up. My website : wnbranch.com
The data, of course, does not show cause. But anybody who ignores such a strong correlation does so at his/her peril.
Oil sloshing? I understand that the tank car isn't filled completely, to allow for expansion of the contents. But to read a lot news stories and online articles, they make it sound like the tank car is half full of oil, and the oil is sloshing around like crazy. How full is a loaded tank car anyway? I can't believe that a tank car designed to carry oil it's whole lifetime would be too overbuilt in size.
Thanks to Chris / CopCarSS for my avatar.
Euclid If oil trains are derailing at over twice the rate of other types of trains, that is a giant red flag that deserves a full investigation.
That's not exactly what they said.
Article Track problems were blamed on 59% of the crashes, more than double the overall rate for freight train accidents, according to a Times analysis of accident reports.
What they said was that oil train derailments were twice as likely as other trains of having a track related cause. They did not say that oil trains were derailing at twice the rate of other trains. Very, very big difference.
A key measure not discussed is what are the cause distributions of other unit trains (coal, grain, double stack, ethanol, etc.). It might be that unit trains have a higher incidence of track derailments because they aren't subject to as much switching as non-unit shipments, eliminating a whole host of human error causes. They may also be newer cars or inspected more thoroughly than the general car population so the mechanical failure causes are less than the car population as a whole.
The statistics are carefully selected and phrased to support the agenda they pushing.
Murphy Siding Oil sloshing? I understand that the tank car isn't filled completely, to allow for expansion of the contents. But to read a lot news stories and online articles, they make it sound like the tank car is half full of oil, and the oil is sloshing around like crazy. How full is a loaded tank car anyway? I can't believe that a tank car designed to carry oil it's whole lifetime would be too overbuilt in size.
Murphy S.: The capacity of a Tan Car is based on the calculation of weight allowed for the specific type of car: [ Loaded Wt (less) Tare wt (equals) Capacity of Product carried in car]. Bear in mind that every product has its own weights .
Like the problems with dry freight in rail cars or trucks[ a lighter product will 'cube out' before it fill the container provided for transport. Heavier weights of products will 'gross out' before the cubic capacity of the container is reached.
"Sloshing" possible? You betcha! Ever see a truck approaching a traffic signal too quickly and make a heavy brake application? With an internally, un-baffled, tank, The 'slosh' (liquid hammer'?) caused by the rapid stopping can cause the truck to be propelled foreward into the intersection by almost a truck length. Potential consequences? Better believe it!.. No reason to believe that a partially laden railroad tanker would not develop a 'sloshing action' relative to its motion(?).
Just for the sake of conversation : [Frm: Ask.com] "...The weight of a gallon of oil depends largely on the oil type. The exact weight can also vary based on what temperature the oil is stored at. Most common oils stand between 7 and 8 pounds, while stored crude oil is around 7.2 pounds per gallon...} (emphasis addd)
and 1 gallon of water weighs roughly 8.33 lbs.
samfp1943No reason to believe that a partially laden railroad tanker would not develop a 'sloshing action' relative to its motion(?).
How would "sloshing action" fore and aft on a tank car cause damage to the track?
I can see maybe shoving the train past a signal. I can see problems holding the train steady after its stopped. How does sloshing damage the track? In most cases track is damaged by vertical forces, impact loading or lateral forces, side to side.
If oils weighs 7 to 8 pounds per gallon, tank cars would have to be about 14% oversized(?) in order to carry 7# oil and 8# oil. If oil weight varies, is every tank car weighed after it's filled? Side note: My father was an over the road trucker. He hauled a lot of cement out of the S.D. Cement plant in the 70's/80's. They had a terrible loading process that took many hours. They would load a truck to what *looked* like the right amount, and then weigh it. Then they ineveitablly had to blow some back out because it was overweight. Then weigh it. Then add more. Then weigh it. Then blow some off etc... When the truckers asked why loading train cars with cement didn't require the same process, they were told that they just knew how much to put in each rail, and besides, "everyone knows the railroads are way overbuilt anyway". This was in the era where the Milwaukee Road and the CNW were both falling apart in S.D.
dehusman samfp1943 No reason to believe that a partially laden railroad tanker would not develop a 'sloshing action' relative to its motion(?). How would "sloshing action" fore and aft on a tank car cause damage to the track? I can see maybe shoving the train past a signal. I can see problems holding the train steady after its stopped. How does sloshing damage the track? In most cases track is damaged by vertical forces, impact loading or lateral forces, side to side.
No reason to believe that a partially laden railroad tanker would not develop a 'sloshing action' relative to its motion(?).
Is is possible for the oil to slosh side-to-side? I have no idea about tank car internals, but it is just a thought.
Anthony V.
dehusmanA key measure not discussed is what are the cause distributions of other unit trains (coal, grain, double stack, ethanol, etc.). It might be that unit trains have a higher incidence of track derailments because they aren't subject to as much switching as non-unit shipments, eliminating a whole host of human error causes. They may also be newer cars or inspected more thoroughly than the general car population so the mechanical failure causes are less than the car population as a whole.
I was thinking along these lines, too. A higher percentage of oil train derailments are caused by track failure, but maybe that's because the cars in the oil trains are in better shape. They don't sit idle as much, they don't get banged around in switching as much and I would guess that they are not as old as many general purpose cars. If other cars have more failures, then the pecentage of rail-related failures go down. In interpreting statistics, you can play with percentages and absolute numbers and come to all kinds of different conclusions.
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
Crash? Crashing?? (amateur newsworker in action)
AnthonyVIs is possible for the oil to slosh side-to-side? I have no idea about tank car internals, but it is just a thought.
Since tank cars are generally intended to run either full or empty, I doubt they are baffled. Full, of course, has to account for the air space we've been discussing.
If it's possible to slosh end-to-end, then side to side would certainly be a possibility.
Jointed rail can be a problem at certain speeds, but I doubt there's much of that left on the routes traversed by the oil trains. As I recall, grain hoppers had a problem with jointed rail and harmonics to the point that they would fall off the tracks.
Even given some jointed rail, the question arises as to whether the period of the harmonic from the jointed rail would square with that of the liquid in the tank.
While such swaying would amplify forces on the track structure, I'd imagine that on CWR minimizes that possibility, leaving things like dips as a more likely culprit. And that goes back to the substructure and how often a line is "surfaced."
Sloshing ? If a RR has 100 unit trains of oil ( 10,000 + cars ) what are the odds that there is one car that was loaded light or even 1/2 full ? 10,000 to one ? A meeting of the odds ? Interesting problem ?
This is not a an endorsement of the sloshing theory but ---
Interesting how on here the suspicions of the Canadian Safety Board experts and others are questioned and/or dismissed.
schlimm Interesting how on here the suspicions of the Canadian Safety Board experts and others are questioned and/or dismissed.
But we have our own panel of "experts" here, don't we?
Norm
According to CFR, loaded tank cars have gross weight limits of 263,000 to 286,000 lbs.
Same with coal. According to BNSF, typical coal-carrying cars also have gross weight limits of 263,000 lbs to 286,000 lbs.
I have just about bit through my tongue on this one.
The article is a mix of fact, fiction, and speculation that no one should take seriously, and no one who can separate the facts from the fiction and speculation will take seriously.
As to the distribution of causes of accidents, most years the distribution is 1/3 equipment, 1/3 human error, and 1/3 track, so at first blush it looks like something is different about oil trains. The article does not provide any basis to support that conclusion, since it does not control for yard versus road derailments. In short the data compared is not comparable. It is apples to bananas.
The sloshing issue is perhaps the worst case of speculation devoid of factual basis. I worked 13 years in the rail transportation of hazardous materials including 2 or 3 when I was a technical advisor to the AAR Tank Car Committee.
Nonpressure tank cars, the kind used to transport oil, are loaded 98% full, or with 2% outage, which is just two ways to say the same thing. A typical tank car designed to haul oil will be sized so that its weight on the rail will be 286,000 pounds or 143 tons, a figure based on the carrying capacity of the journals. The designer strives to make the car as light as possible so it can carry as much product as possible. Excess tare weight comes directly out of the load, which increases the effective cost of transportation.
If we assume our cars weigh 35 tons empty, a ballpark figure, then the load will be 108 tons. The weight on rail will be 143 tons, or 71,500 pounds per axle, assuming the car is loaded full, is stationary, and is on level track.
How much "slosh" can there be? The answer is 2% of the load or 2.16 tons, lets say 2 tons to keep the math simple. Assuming maximum movement due to dynamic braking, or moving up or down a mountain grade, or any other cause or combination of causes, the greatest weight transfer is 2 tons which would add 2,000 pounds to the axle loading on the heavy end and subtract 2,000 pounds per axle on the light end. That is less than 3% increase in axle loading, an insignificant figure.
The story that oil trains have a magic ability to cause or find track defects is male bovine excrement.
Mac McCulloch
So that 2% of the volume being air would compare roughly with the air in a soda bottle. Hardly enough to notice, even if it is 140 tons of product instead of 20 ounces.
Fair enough, and enough for me to discount the sloshing phenomenon as a major player.
PNWRMNMNonpressure tank cars, the kind used to transport oil, are loaded 98% full, or with 2% outage, which is just two ways to say the same thing. Mac McCulloch
Can you provide a technical reference that says that Bakken oil in unit trains is loaded 98% full in the cars? You may be right, but someone else here gave a fairly detailed description that had a lot more air space than 2%. So I don't know who to believe.
Euclid PNWRMNM Nonpressure tank cars, the kind used to transport oil, are loaded 98% full, or with 2% outage, which is just two ways to say the same thing. Mac McCulloch Can you provide a technical reference that says that Bakken oil in unit trains is loaded 98% full in the cars? You may be right, but someone else here gave a fairly detailed description that had a lot more air space than 2%. So I don't know who to believe.
PNWRMNM Nonpressure tank cars, the kind used to transport oil, are loaded 98% full, or with 2% outage, which is just two ways to say the same thing. Mac McCulloch
I could give you the citation for 49 CFR, but do not feel like looking it up.
If a shipper is using a car having more gallons of capacity than is necessary, that is a car designed for a lighter commodity, then the outage would be more than 2%. That would be legal. The 2% outage is a regulatory minimum, but if the car is designed for crude oil then it will be appropriatley sized to minimize tare weight and maximize lading weight.
I did not find any description of loading oil cars in this thread.
I can tell you it is not rocket science. If car is designed for oil, just load to the 2% indicator in the manway or meter in gross gallons stencilled on the end of the car less 2%. If the car was not designed for oil, or designed for oil lighter than what is being shipped, loader has to convert net weight allowed in car to gallons and then either meter, or figure out correct outage and how to measure that outage. If a car has more volume than it should, it can be overloaded. Covered hoppers have the same issue. If you load wheat, at 60 #/bu into a car sized for corn at 46#/bu, physically full then you have seriously overloaded the car by weight. The issue is not oil, it is proper loading of the cars.
Mac
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