Euclid However, I have been informed that the only thing that can perturb a derailed, dragging truck to start a pileup is another derailed car.
But I am not sure how to reconcile that because I have always heard that emergency applications can cause a derailment. And I would think that a derailed, dragging truck would be particularly vulnerable to being disrupted into chaos by an emergency brake application.
Dave H. Painted side goes up. My website : wnbranch.com
This device seems to meet the kiss principle (Keep It Simple Stupid) in that it doesn't require batteries or many active parts. There are two pans, one on each side of the center of the truck in the proximity of the actuators where displacement of the truck in any direction from its accepable position will contact one or the other actuator. The video shows a conventional freight truck. How it would old up in all of the weather conditions an oil train might experience from -40 degrees and deep snow in North Dakota to the summer heat remains to be tested. Ice & smow buidup could cause false activations. Looks to me like it's worth a trial. Could someone stage a derailment on an equiped train at Pueblo?
I think we are looking at a 'cartoon' CGI animation of the system, not an accurate illustration of how the parts are arranged.
I was assuming that the ramps that are the periphery of the 'pan' act as a limiting surface of the 'envelope' of permissible truck rotation and excursion. Part of why I think the pan should be curved is to ensure, as you noted, that if the truck frame drops inside and down the relevant section of the ramp surface doesn't get pulled out and away to the point the valve won't be triggered. But I feel sure the Spanish developers are not fools and have arranged the physical pans used (on three-piece trucks, at least -- the problem doesn't seem as pronounced for the passenger-car trucks illustrated) so that any substantial truck motion away from 'railed' tracking compliance will fire the valve. Is there a failure mode of a three-piece truck in skew that would allow the pan to be pulled away from the pin before the ramp edges could reach it? If so, the system should be modified to correct that situation (perhaps by puting a little preload on the valve pin. relaxing of which would also open some percentage of the valve area in release?)
Personally I think it would be interesting to look at all the dynamic motions a truck might assume in a derailment, and see what configuration of 'pan and pin(s)' might work to a sensible number of 'nines' confidence...
Wizlish Oh, fer crying out loud, the "pan" is just a multiaxis ramp mounted on the truck frame. If it moves too far in any direction it depresses the pin on the valve, which puts the brake in emergency (probably acting much like the tripper valve on a NYC subway car).
EuclidHere is a mechanical derailment sensor that does appear to monitor the position of the truck rather than detecting vibrations. Apparently the rectangular metal pan allows a feeler pin to move over its area, as the normal range of truck motion encompasses. Somehow a derailment disrupts this physical relationship of the pan and feeler pin, which causes an emergency application of train brakes.
Oh, fer crying out loud, the "pan" is just a multiaxis ramp mounted on the truck frame. If it moves too far in any direction it depresses the pin on the valve, which puts the brake in emergency (probably acting much like the tripper valve on a NYC subway car). Note that this is mentioned as being a simple, pure pneumatic system, with no proportional or electrical logic, etc. There are some comparatively simple enhancements to this idea that I think will prove very effective in control of an ECP brake.
[Rather obvious potential improvements: curve the 'pan' slightly so the pin follows in 'register', and make the pan specially shaped in perimeter to control vertical vs. rotary deflection (or discriminate curving vs. skew vs. rotation) before the system is triggered...]
I hope folks reading this thread pay careful attention to the claims made in that video from about 4:45 onward. Among these: the device has already been installed on over 1000 cars, and is claimed to have worked correctly in "100%" of the events (presumably derailments) experienced so far.
Personally, I think the system needs a critical modification: if it puts the train brake in emergency, it should also reduce brake pressure on the truck whose detector has been actuated. Full emergency application of braking on a derailed truck is NOT likely to produce deceleration of the right kind -- is the foundation set up to pull the truck roughly into parallel alignment with the car frame and hold it there?
Ruderunner's plan assumes that the truck will be rotated MORE than the car or the other truck.
What happens when the trailing axle derails the truck is rotated LESS than the other truck?
The rear truck is rotated 3 degr and the lead truck is rotated 1 degr. Niether would hit the limit switches.
ruderunner Paul thank you for that reference. I'm still curious of how much deflection a truck with one wheelset off the rails has.
Also what would normal track speed be in that 23degree curve?
Assuming minimal superelevation, somewhere in the 10 mph (or less) range.
ruderunner Lets define derailment, basically the flanges are no longer both between the rails. It doesn;t have to include a big flaming pileup (though thats what the general public thinks)
Lets define derailment, basically the flanges are no longer both between the rails. It doesn;t have to include a big flaming pileup (though thats what the general public thinks)
That's not an inclusive definition. If there is wide guage or a loose wheel you could have both wheels between the rails.
And frankly if the trucks aren't pointed the same direction that the carbody is, wouldn't that indicate a derailment?
Frankly no. The only time the trucks will be pointed the same way the car body is is when the car is on tangent track. If the car is on any type of curve the trucks will be pointed differently from the carbody, and the trucks will only have the same rotation (in opposite directions) when they are on the circular portion of a curve. When they are in switches, turnouts or spirals the trucks will have differing amounts of rotation.
ruderunnerZugman, that's just plain old sabatoge...
What?
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
Paul_D_North_Jr tree68 [snipped - PDN] . . . The devil is in the details, however. . . . The truck deflection detector, for instance - how does one reconcile sharp curves with the potential that a truck might not deflect enough, even though derailed? I'll go back to that example of the car on a western railroad that ran a number of miles before rerailing itself. It may never have reached the deflection limit. . . . Just about all equipment has to be able to negotiate a 12-degree curve (in a 100 ft. chord), and most has to be able to get around a 23-deg. curve (250 ft. radius). For a car with 50 ft. truck centers (roughly 70 ft. long), each truck would be angled from 3 deg. to about 6 deg. from the centerline axis of the car. Larry - the train that ran a long distance over a switch machine, etc. and then rerailed itself was a RoadRailer - see: "The Invisible Derailment - If a RoadRailer trailer derails in the middle of the night and nobody notices, does it still derail?", by Larry Gross, from Trains, November 2007, pg. 52 &etc. ["Magazine Index" 'keywords': derailment prototype roadrailer ] - Paul North.
tree68 [snipped - PDN] . . . The devil is in the details, however. . . . The truck deflection detector, for instance - how does one reconcile sharp curves with the potential that a truck might not deflect enough, even though derailed? I'll go back to that example of the car on a western railroad that ran a number of miles before rerailing itself. It may never have reached the deflection limit. . . .
Just about all equipment has to be able to negotiate a 12-degree curve (in a 100 ft. chord), and most has to be able to get around a 23-deg. curve (250 ft. radius). For a car with 50 ft. truck centers (roughly 70 ft. long), each truck would be angled from 3 deg. to about 6 deg. from the centerline axis of the car.
Larry - the train that ran a long distance over a switch machine, etc. and then rerailed itself was a RoadRailer - see:
- Paul North.
Paul thank you for that reference. I'm still curious of how much deflection a truck with one wheelset off the rails has.
Anybody know?
Modeling the Cleveland and Pittsburgh during the PennCentral era starting on the Cleveland lakefront and ending in Mingo junction
Euclid Regarding the comment by Ruderunner: “And doing something, even if its wrong, is a step in the right direction.” There are two ways of interpreting this comment. One way is to interpret “doing something” as doing a full implementation of some untested improvement without knowing whether it will work or not; as though you have to take that much of a gamble. That would be absurd, and the railroad industry is the last institution that would make that mistake. For critics here to highlight the risk of doing a full implementation of something that might not work is a giant red herring to attempt to shoot down suggestions for improvement. The other way to interpret what Ruderunner meant by his comment is that “doing something” means doing research, design, and testing as a developmental process BEFORE any system-wide implementation. In “doing something” as research and development, there is indeed a process of “doing something even if it’s wrong” and having it become a “step in the right direction.” That kind of trial and error is the core of research and development.
Exactly! Doing nothing while potential for accidents looms is almost always a guarantee to fail. Or said differently, to try brings the chance of achieving a goal or not achieving it. But to not try is guaranteed to not achieve the goal.
Zugman, that's just plain old sabatoge...
Larry, I get your point but see the above. As for too much air useage, perhaps time to rethink a truck mounted generator? Something that doesn't require special wheelset or trucks. An add on system if you will.
ruderunnerNow I'm asking for some clarification on a topic that was touched on earlier, namely braking effort. My understanding is that railcar brakes are designed to affect the highest level of braking that an EMPTY car can stand without sliding wheels. Is that correct? If so then loaded cars are dramatically underbraked (meaning they don't stop nearly as fast as they could) so the statement that railroaders like to throw out that "throwing the train into emergency is the fastest way to stop a train" isnt always true. It IS the fastest way to stop a trains of empties, but far from the fastest way to stop a loaded train.
If so then loaded cars are dramatically underbraked (meaning they don't stop nearly as fast as they could) so the statement that railroaders like to throw out that "throwing the train into emergency is the fastest way to stop a train" isnt always true. It IS the fastest way to stop a trains of empties, but far from the fastest way to stop a loaded train.
ruderunnerNow I'm asking for some clarification on a topic that was touched on earlier, namely braking effort. My understanding is that railcar brakes are designed to affect the highest level of braking that an EMPTY car can stand without sliding wheels. Is that correct?
Yes. That's correct. The braking force is constant regardless of load.
ruderunnerIf so then loaded cars are dramatically underbraked (meaning they don't stop nearly as fast as they could) so the statement that railroaders like to throw out that "throwing the train into emergency is the fastest way to stop a train" isnt always true. It IS the fastest way to stop a trains of empties, but far from the fastest way to stop a loaded train. If all the brakes are operating at a level that provides maximum braking (without wheelslide) isn't reasonable to assume then that a loaded train can stop much faster than it currently can? No not as fast as an empty train but a dramatc improvement none the less.
For any given, train with existing braking, emergency is the fastest way to stop. It provides the most braking force each car can provide at that moment.
If you mean that at train with load proportional braking could stop faster than one without it, then yes, that's true.
So, when you hear "trains take a long distance to stop because they're heavy", that's not quite right. This is what you're getting at....
But, here's the rub. Load sensing braking systems aren't popular because:
In short, it's more trouble than it's worth - and it's not risk-free.
Now, could you develop ECP and on-car sensors to do a much better job of braking, alow higher speeds, prevent derailments, mitigate derailment damage, etc, etc. Sure. But it will take lots of dollars and a ton of R&D to get there.
-Don (Random stuff, mostly about trains - what else? http://blerfblog.blogspot.com/)
From what I understand, the load/empty sensors reduce braking effort for empties. So if a train is loaded, then it will still have full braking ability.
But throwing the train into emrgency is still going to yield the most braking force as the brakes are currently configured:
When an emergency application is enabled, the emergency portion of the reservoir is combined with the auxiliary reservoir. That causes the aux.reservoir pressure to be higher than the brake cylinder, and you will get ~ 20% more pressure in the brake cylinder then you would at full service or equalization.
ruderunner If so then loaded cars are dramatically underbraked (meaning they don't stop nearly as fast as they could) so the statement that railroaders like to throw out that "throwing the train into emergency is the fastest way to stop a train" isnt always true. It IS the fastest way to stop a trains of empties, but far from the fastest way to stop a loaded train.
If all the brakes are operating at a level that provides maximum braking (without wheelslide) isn't reasonable to assume then that a loaded train can stop much faster than it currently can? No not as fast as an empty train but a dramatc improvement none the less.
Probably yes.
And doing something, even if its wrong, is a step in the right direction.
That is just flat wrong.
Wasting time, wasting money, and not improving anything isn't helping anything.
I would like to point out that all the schemes being proposed here, the derailment detectors, the load/empty adjustors, the differential braking are like seat belts and parachutes. They don't prevent the crash they just provide some possibility of lessening the consequences. None of the schemes presented prevent a derailment. None prevent a pile up. None prevent a car from being breached. None. Not one. They all just make the pile smaller. Many times making the pile smaller is the right answer. Doing random stuff just to be doing stuff is not.
Railroads have determined that joints in rail are a weak spot in the track. So they invented continuous welded rails. They found that field welds (thermite welds) are less reliable than factory welds (electric flash welds). They found that field welds near the ends of bridges are incrementally higher in risk. So many railroads have been actively removing field welds near the ends of bridges and replacing them with "in track welds" which are almost as reliable as factory welds. Factory welds are still a risk so some railroads are ordering 480 ft rails, rolled as a single piece. That required building a ship and developing a loading system to get them on and off the ship without damaging them. Now a 1/4 mile CWR string only has 2 welds in it instead of 15-30 in a conventional string.
Those activities ELIMINATE RISK. The weld can't fail because the weld isn't in the track.
That is how you improve safety. You do stuff that actually works.
Roadrailers at Sandusky Bay
Never too old to have a happy childhood!
One of my concerns about the system is that there are instances where a longer slowdown period would result in the cars hitting and sticking on switches or grade crossings that they would miss if they slow down as rapidly as possible.
ruderunnerAnd doing something, even if its wrong, is a step in the right direction.
For that matter, one could simply point out some feature of the current system, tout it as "improved," and the public would be similarly asuaged. Say, f'rinstance, two-way EOT's.
The problem with doing something "wrong" is that it costs money, and doesn't provide a return on investment. And that money has to come from somewhere.
And if something happens despite having employed that "wrong" solution, then the credibility of all solutions comes under suspicion. Look at the "better solution" 1232 cars...
I think most of the criticism of any of the derailment prevention/minimization systems presented here is based on knowledge of the realities of railroading. There are probably parts of all of them that have merit, or would after some tweaking.
The devil is in the details, however. Power, communications, durability, and a host of other factors all figure in. Like - how much air would all of those air turbines consume on a 100 car train?
The truck deflection detector, for instance - how does one reconcile sharp curves with the potential that a truck might not deflect enough, even though derailed? I'll go back to that example of the car on a western railroad that ran a number of miles before rerailing itself. It may never have reached the deflection limit.
The biggest thing to remember here is that we aren't attacking the person with the ideas - if anything, we're giving them information that they can go back with and refine their idea.
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...
So if I say that we should make the oil car wheels square, that is a step in the right direction?
dehusman Taking the oil train derailment under discussion as an example there were about 9 cars that derailed prior to the pile up. At 40 mph a train travels about 60 ft per sec, which is about a car length in this case. So its reasonable to say that there was between 8 and 10 sec between the first wheel hitting the ground and the general pile up. If the system just notifies the train crew and takes no action, it will take a couple seconds for the trucks to skew enough to trip the sensors, another sec or two for the electronics to communicate to the head end. Then the crew will have to realize they have an alert, do whatever they have to do to acknowledge it, then take whatever action they are going to take. Realistically they are down to maybe 4-5 sec before the pile up occurs. Even if they plugged it and had ECP, it would still take a couple sec for the brakes to actually apply. In this case the difference between the derailment putting the train in emergency and the crew putting the train in emergency is 2-3 sec. If the system applied a penalty or full service reduction, the train would have gone in emergency 4-6 sec seconds later. The real benefit of this type of system is with a train like the ones in some of the other videos where the empty cars are drug for long distances without the train going in emergency. As has been pointed out several times before, the situations where a car will travel upright and in line in a train with one end derailed for miles are situations where the car is an empty. If the car is a load, our friend gravity will cause it to dig in and result in a pile up much quicker.
Taking the oil train derailment under discussion as an example there were about 9 cars that derailed prior to the pile up. At 40 mph a train travels about 60 ft per sec, which is about a car length in this case. So its reasonable to say that there was between 8 and 10 sec between the first wheel hitting the ground and the general pile up.
If the system just notifies the train crew and takes no action, it will take a couple seconds for the trucks to skew enough to trip the sensors, another sec or two for the electronics to communicate to the head end. Then the crew will have to realize they have an alert, do whatever they have to do to acknowledge it, then take whatever action they are going to take. Realistically they are down to maybe 4-5 sec before the pile up occurs. Even if they plugged it and had ECP, it would still take a couple sec for the brakes to actually apply.
In this case the difference between the derailment putting the train in emergency and the crew putting the train in emergency is 2-3 sec. If the system applied a penalty or full service reduction, the train would have gone in emergency 4-6 sec seconds later.
The real benefit of this type of system is with a train like the ones in some of the other videos where the empty cars are drug for long distances without the train going in emergency. As has been pointed out several times before, the situations where a car will travel upright and in line in a train with one end derailed for miles are situations where the car is an empty. If the car is a load, our friend gravity will cause it to dig in and result in a pile up much quicker.
Yes, every second counts. So some feedback on how many seconds, how many degrees etc willhelp dial in the system.
FWIW electrical siginals travel at nearly the speed of light so knock off 2 seconds from yur math. But even using your example that 9 car pile would have been only 6 (or less) Thats nearly a 30% reduction right there.
Now I'm asking for some clarification on a topic that was touched on earlier, namely braking effort. My understanding is that railcar brakes are designed to affect the highest level of braking that an EMPTY car can stand without sliding wheels. Is that correct?
I'd also like to remind fourm members that "perceptin is reality" And the percieved reality of the general public is fast becoming that oil trains are rolling firebombs waiting to go off. I think it's in the industrys best interest to be proactive about this, certainly before the government decides to do something.
BaltACD Isn't reality amazing!
Isn't reality amazing!
I haven't heared any better suggestions from you...
Perhaps you have your own ideas about how to prevent big derailments, care to share?
Seriously though, you have some experience in railroading. Do you have any suggestions that may help the situation? You really are coming off as just a grumpy old head rather than being proactive about a problem facing your industry. I'd love to hear some hairbrained idea you might have had no matter how uncoinventional or uneconomic it may be. Who knows, it may just change railroading as we know it...
Euclid I think it would take a couple measures of different factors for a sensor to add them up and conclude that a derailment has occurred. But let me ask this. If a device detected a derailment, what should the proper response be? The first objective would be to get stopped, possibly limiting the destruction by stopping quickly.
Exactly, stop the train and fix the derailed wheelset (if possible) A train doesn't always fly off the tracks as soon as the wheels leave the rails.
Wouldn't it be nice to catch a derailment early? That's what I'd like to accomplish. And frankly if the trucks aren't pointed the same direction that the carbody is, wouldn't that indicate a derailment?
dehusman Depending on how you are measuring it, you will need somewhere in the 7-9 degree range of travel. You want it to go through a #9 frog without alerting. A #7 frog has an angle exceeding 8 degrees. With only 2 degrees you will most likely get a false positive through every diverging route on a swtich with a speed less than 30 mph. Every false positive will un-necessarily stop and delay the train about 2 hours.
Depending on how you are measuring it, you will need somewhere in the 7-9 degree range of travel. You want it to go through a #9 frog without alerting. A #7 frog has an angle exceeding 8 degrees.
With only 2 degrees you will most likely get a false positive through every diverging route on a swtich with a speed less than 30 mph.
Every false positive will un-necessarily stop and delay the train about 2 hours.
Very possibly true. Again, how far does the truck need to rotate relative to the car body to negotiate such trackage?
Conversly, how far would a truck have to rotate to drop one wheelset off the rails?
I suppose this would vary according to a cars wheelbase (center to center of kingpins) so adjustments need to be made according to car size. Not a big deal at all to do that.
tree68 If you are going to introduce a thirty second delay, you might as well not put the sensor on the car in the first place. A lot will happen in thirty seconds. A train travelling at 30 MPH will travel a quarter mile in that time. Remember that the Lynchburg derailment only involved about 1200 feet of track...
If you are going to introduce a thirty second delay, you might as well not put the sensor on the car in the first place. A lot will happen in thirty seconds. A train travelling at 30 MPH will travel a quarter mile in that time.
Remember that the Lynchburg derailment only involved about 1200 feet of track...
And what prey tell could be done in 30 seconds to prevent a derailment? If it happens that fast, nothing can stop it. Ok so maybe we try it with a 5 second delay? How about 10 seconds? Whats your suggestion besides "don't bother"?
BUT, what about situations where a wheelset has been dragging for the last mile? It might be fine till it come to a crossing, switch, bridge or whatever. Wouldn't you like to know you have a truck off the rails before that?
Am I proposing to stop all derailments? No but early detection is the best way to prevent any derailment (or disease or catrastophie or fill in the blank)
tree68 ruderunner 2 degrees off the centerline So, how is that going to work on a 5 degree curve (or tighter)? Not all lines are straight as an arrow.
ruderunner 2 degrees off the centerline
So, how is that going to work on a 5 degree curve (or tighter)? Not all lines are straight as an arrow.
How much would the trucks need to rotate relative to the carbody to round that curve?
And once both trucks are in the curve, the logic detects that so no false alram.
I really need to find some time to draw some skecthes and do a thorough explanation of what I envision.
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