Overmod,
I am looking over your comments, and have a few observations at this point. I don’t see any basis to conclude that (i) and (ii) are sequential steps. It says “or” between them. I don’t see how that can be dismissed as not meaning that there is a choice between the two alternatives.
I do understand your point that (ii) might be part of (i) because causing slack to adjust in (i) requires moving the train, and moving the train seems to be a part of (ii). However, (ii) actually says nothing about moving the train. It only says to apply tractive force, and that could mean just pushing against the stationary train to see if it moves. That is why I say that (ii) needs to be rewritten to say what it means.
In any case, let’s consider that (i) requires moving the train in order to cause the slack to adjust if simply allowing it to adjust will not work. I wrote about that in my analysis of Procedure (i). I could not see any way to cause slack to adjust. How would you do it?
The only way I can think of is to shove the whole train up-grade; that is 20 cars of handbrakes and all of the remaining tonnage; then set the independent to cause all slack to run out. Once it seems that all slack has run out, then immediately release the independent. At that point, the only brakes applied are the 20 cars of handbrakes next to the engine.
Then wait a moment and all the stretched slack on the grade will run back down and bunch against the cars with handbrakes. If the cars with handbrakes set stop the rolling train, then that would amount to causing the slack to adjust. Although one might argue that the slack may still have some surprises introduced by all the un-braked cars running up against the obstacle of 20 cars of handbrakes. There is going to be a lot of compressed draft gear in those un-braked cars. How would you cause the slack to adjust with the grade and train of my example?
I am going to write a letter to the TSB and ask them to explain the meaning of their handbrake effectiveness test instructions.
OK, I think I see the problem now. I think you are mistaking items (i) and (ii) for alternatives. They are not; they are sequential steps, or ought to be, whether or not distinguished with 'or' in the language.
FIRST you ensure that when you release the air (and the slack action or other forces 'frozen' by the application relax) the cut doesn't keep moving once slack forces stop. (That gets rid of surprises)
THEN you apply power and ensure that the cut stops when the music does. (This confirms you have an added margin of safety over jostling)
Technically, part of (ii) is actually expressed as part of (i), which I think you missed in its intent; note the language 'or cause' in the discussion of slack there? this is necessarily done with the power if the slack fails to move out completely on brake release, and how would you know from the cab?
Now, this does open the question of how hard do you pull or push, and how far do you go, before idling the power and watching for movement? Either forward or back, the power move would move the draft gears involved to their stops relatively smoothly, and your concern ends at the end of the 'secured' block(since the remaining cars have had their brakes released, and must remain so during the balance of (ii) for the issues potentially present in (i) to have been resolved.)
Now, what (ii) doesn't say is how far you pull or push to perform the test: I would surmise it is far enough to move all the secured cars and the draft gears between them, but might just involve a certain amount of throttle for a certain time if there is little physical movement. The general consensus is that applied handbrakes won't exert enough physical force on the wheelrim to induce flat-spotting wheelslide, but the 'worst case' would be compressing the train 'downhill' until you reach the effective node between the compression due to the set and the force of the trailing consist pulling the rest of the 'set' downhill, after which things would stabilize. I would then pull the set back uphill to stretch it again, and idle the power to see if anything moves; both (i) and (ii) then say it should not move.
If I understand the current Canadian rules, locomotives only 'secure themselves'; they don't count toward the minimum recommended set, and probably shouldn't based on what I have read about their handbrake efficacy.
And yes, if it KEEPS moving after you finish with either step, you have to go set more brakes...
Overmod tree68 Euclid The problem is that the train can suddenly become unsecured and moving. And how is that supposed to happen? At the risk of getting further into tar-baby threads on a crappy phone: One significant issue is that a 'train' stopped on a grade, especially with emergency application, may retain significant energy in slack or buff. Another is that there is no way at present to measure either physical force exerted by a handbrake on the wheels or whether there is any slack or lost motion in the foundation that would tend to release set if the car is given a shock or allowed to roll. These become significant because our old friend 'coefficient of sliding friction' is very likely to be lower between shoes and wheels, again in a way impossible to predict except by pushing in the absence of shock action... in other words, once all the 'surprises' in slack action or lost motion have been shaken out of the consist.
tree68 Euclid The problem is that the train can suddenly become unsecured and moving. And how is that supposed to happen?
Euclid The problem is that the train can suddenly become unsecured and moving.
And how is that supposed to happen?
At the risk of getting further into tar-baby threads on a crappy phone:
One significant issue is that a 'train' stopped on a grade, especially with emergency application, may retain significant energy in slack or buff. Another is that there is no way at present to measure either physical force exerted by a handbrake on the wheels or whether there is any slack or lost motion in the foundation that would tend to release set if the car is given a shock or allowed to roll.
These become significant because our old friend 'coefficient of sliding friction' is very likely to be lower between shoes and wheels, again in a way impossible to predict except by pushing in the absence of shock action... in other words, once all the 'surprises' in slack action or lost motion have been shaken out of the consist.
I like your point about the need to shake out all the surprises in slack action. As you know, a key point in all of this is that it is not good enough to set handbrakes, release the air, and consider the train secured simply because it does not move when the air is released.
To “fix or attach something” is only half of the definition of “secured.” The other half is “so it can’t move.” It is the second half of the definition that is the challenge of train securement.
In pondering what the TSB has said about the impossibility of verification, it has led me to delve into the push/pull test as defined in Rule 112. In that definition, there are two methods offered for verification. They are detailed as (i) and (ii). Notice that (i) and (ii) is not a two-part procedure. Instead they are separated by the word or, and thus are offered as two different options in which either one fulfills the requirement for verification.
Notice that option (i) definitely “shakes out the surprises.” Once those surprises are shaken out, the option apparently assumes there is no reason to move the train to see if it stops when power is shut off. Just having it stopped with only handbrakes holding it is apparently deemed to be good enough if there are no surprises lurking in the consist which may suddenly bump the cars into motion.
So with option (i), there is no reason to apply tractive force against the train to see if it moves –or- to apply tractive force against the train to cause it to move and then stop applying tractive force to the train to see whether it stops moving. Neither one of those tests are needed with option (i). Although this does raise the question of why option (ii) is needed if option (i) gets the job done.
Furthermore, with option (ii), there is no shaking out of the surprises as is a part of option (i). If anything, option (ii) is likely to “bottle up” surprises or even create surprises if none already exit.
What is not clear is why that, for any given train securement, two different options are offered with each one yielding different results.
Also very interesting is the fact that the language of option (ii) is completely ambiguous because you cannot prevent equipment from moving by applying tractive force. Option (ii) needs to be rewritten.
It would be very easy in interpret option (ii) as only requiring applying some force to the train to see if it moves. So if it does not move, you pass the test. Of course there would be a strong motive to apply the least amount of force possible, because it if moves, you have to go and set more handbrakes. And one might mistakenly believe that: “if it does not move in the first place, it has to be secured, right? So why not let sleeping dogs lie? Why let perfect be the enemy of good enough?”
OvermodSo what we appear to be left with is a two-part procedure, first 'normalizing' all the in-train forces and then testing the 'set' applied to the train. It's the first condition that appears to be causing all the difficulty for Euclid and perhaps by extension some of the TSB people.
It is not causing any difficulty for me. It is only the TSB that is questioning it as far as I know. My only point here is to learn why the TSB has questioned it. I think it is flat-out astounding that they have made the statement that I quoted above. And almost as astounding is that it seems to not register with some people here. I guess that maybe they just don’t have any experience with securing large trains on high grades.
The 'catch' on a grade is that you can't achieve that without at the very least releasing the automatic enough for the various cars to equilibrate' ... with the immediate problem on 'high grade' that no combination of independent snd dynamic will hold the train when that is done.
This leaves aside all the questions about 'when is a handbrake set?' which are best left to a separate thread from this one; once again though if you have a non-moving car that gets 'hit' enough to start its wheels turning it may keep moving, and while it might 'damp down' and stop it might also 'want' to accelerate. At the level of mass and momentum involved even comparatively slow, or short-distance, changes may add up to significant forces relatively quickly.
So what we appear to be left with is a two-part procedure, first 'normalizing' all the in-train forces and then testing the 'set' applied to the train. It's the first condition that appears to be causing all the difficulty for Euclid and perhaps by extension some of the TSB people. I think however that in this particular thread we should cover only the issue of securement eastbound at Nantes, and redirect the theoretical downhill shenanigans into its own new discuss-a-thon.
Now for the yes-buttering up: it was my understanding that Harding's train, when stopped, had all the meaningful slack out of the actual hazmat-containing cars entirely. However, it was left hanging on independent with extended slack between locomotives, a point I will mention in a moment. Accordingly there is no real risk of run-in causing handbrakes set progressively from the front to slip if a pull test on the secured portion of the consist reveals adequate set. Likewise I'd expect a push (against the securement, downhill) followed by a pull to ensure 'no surprises' from any residual slack action, and presumably the train will be reasonably 'stretched' again at the conclusion of such a test.
We do not care about issues of slack bunching... but we might be concerned about subsequent failure of the independent if the locomotive consist itself were not tied down correctly ... an issue the TSB appeared to be working hard to establish for, then, somewhat irrelevant reasons. It might be possible for unsecured engines to roll back against the 'set' portion and cause it to start -- I think this unlikely at Megantic for a variety of reasons including the rate at which the independent was reported to have bled off.
I don't think anyone here has tried to assert that the independent would not hold that train, "overweight" or otherwise, on that grade; not only did it do so while Harding was fiddling about, it continued to do so until the independent pressure had fallen to almost astoundingly low level (can't check the exact number in the report and threads discussing it on this phone). This may be an indication that a simple pull test would give Rule 112 securement even if the power were to turn out to be inadequately secured itself and rolled back against the set portion as the independent bled off.
I'll be looking forward ... in another thread ... to reading further about correct and 'safety first' real-world procedures to assure a set on an emergency-braked loose-car consist stopped on a heavy downgrade. As a matter of general interest, not something relevant to the trial or Tom Harding's 'fate'.
once again, either the phone or the Kalmbach forum software has started duplicating posts.
dehusman The fallacy in Euclid's theories is that railroads tie down cuts on grades thousands of times a day all over North America (well actually the world). Regardless of what the TSB says, 99.999999999999999999% of them stay put when properly secured. An overwhelming majority of people would agree that the Lac Megantic train was not properly secured.
The fallacy in Euclid's theories is that railroads tie down cuts on grades thousands of times a day all over North America (well actually the world). Regardless of what the TSB says, 99.999999999999999999% of them stay put when properly secured. An overwhelming majority of people would agree that the Lac Megantic train was not properly secured.
Johnny
Dave H. Painted side goes up. My website : wnbranch.com
tree68 Euclid If the train does not move, it is secured, and of course, that is the goal of management. The problem is that the train can suddenly become unsecured and moving. The TSB is saying that locomotive engineers cannot accurately know that won't happen. And how is that supposed to happen?
Euclid If the train does not move, it is secured, and of course, that is the goal of management. The problem is that the train can suddenly become unsecured and moving. The TSB is saying that locomotive engineers cannot accurately know that won't happen.
I suspect TSB verison of a 'tight' handbrake is spinnng the handbrake wheel until it stops spinning without any effort to get additional clicks to the level of the operators maximum strength. Properly applying a handbrake is all about what happens after the brake wheel stops easily spinning. Once the brake wheel has been applied with maximum force, visually confirming that the brake shoes are against the wheels while proceeding to the next car.
Never too old to have a happy childhood!
That is what I would like the the TSB to explain. All I can do it read between the lines to try to discover their reasoning. I think that what I have posted about procedures (i) and (ii) above relates to the reasons why the TSB believes that the push/pull test is unreliable. That is why I wrote those posts. I wanted to upack the push/pull test language of revised Rule 112. Maybe I should also look at the old rule.
One way that I believe a train can suddenly become unsecure and moving is by being subjected to wind force or thermal changes. These risks may generally be moderate, but could be critical especially if the handbrake effectiveness test passed with very little safety margin. I believe that the impossibility of knowing how much safety margin a passing test has acquired is very much a part of the TSB's warning about the risk of a faulty handbrake effectivness test.
EuclidIf the train does not move, it is secured, and of course, that is the goal of management. The problem is that the train can suddenly become unsecured and moving. The TSB is saying that locomotive engineers cannot accurately know that won't happen.
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...
tree68 Euclid quoting the STB of Canada: "...locomotive engineers cannot accurately know that management’s expectations have been met every time cars are secured in accordance with CROR Rule 112.” Common sense (which is, of course, not that common) would seem to dictate that if the train doesn't move, it's been adequately secured. If management has some other goal in train securement, it would be, well, interesting...
Euclid quoting the STB of Canada: "...locomotive engineers cannot accurately know that management’s expectations have been met every time cars are secured in accordance with CROR Rule 112.”
Common sense (which is, of course, not that common) would seem to dictate that if the train doesn't move, it's been adequately secured. If management has some other goal in train securement, it would be, well, interesting...
If the train does not move, it is secured, and of course, that is the goal of management. The problem is that the train can suddenly become unsecured and moving. The TSB is saying that locomotive engineers cannot accurately know that won't happen.
Euclid"...locomotive engineers cannot accurately know that management’s expectations have been met every time cars are secured in accordance with CROR Rule 112.”
Euclid http://www.bst-tsb.gc.ca/eng/rapports-reports/rail/2011/r11q0056/r11q0056.pdf Quote by the TSB of Canada: “Locomotive engineers who apply hand brakes do not receive any definitive feedback to confirm that sufficient brake shoe force was attained. Furthermore, because it is impossible to verify hand-brake effectiveness by pulling or pushing cars on high grades, locomotive engineers cannot accurately know that management’s expectations have been met every time cars are secured in accordance with CROR Rule 112.”
http://www.bst-tsb.gc.ca/eng/rapports-reports/rail/2011/r11q0056/r11q0056.pdf
Quote by the TSB of Canada:
“Locomotive engineers who apply hand brakes do not receive any definitive feedback to confirm that sufficient brake shoe force was attained. Furthermore, because it is impossible to verify hand-brake effectiveness by pulling or pushing cars on high grades, locomotive engineers cannot accurately know that management’s expectations have been met every time cars are secured in accordance with CROR Rule 112.”
Reality can't intrude on the TSB's book experience. So according to the TSB trains can't be secured - so why try! Let them roll!
Euclid Euclid tree68 From current CROR Rule 112: (e) When hand brakes are used, an effectiveness test must be performed as follows: release all air brakes and, (i) allow or cause the slack to adjust. It must be apparent when slack runs in or out, that the hand brakes are sufficient to prevent the equipment from moving; or (ii) apply sufficient tractive effort to determine that the hand brakes provide sufficient force to prevent the equipment from moving when tractive effort is terminated. HAND BRAKE EFFECTIVNESS TEST PROCEDURE(i) Say you are moving a train down grade and stopping with air, and when stopped, the air is holding the train with slack bunched. You set 20 handbrakes on the head end of the train. If you test with procedure (i), the test is not completed unless an adjusting of slack occurs after releasing the automatic brake. You have the option of allowing or causing the slack to adjust, but the adjustment must occur in order to complete the test with procedure (i). When the air is released under procedure (i), one possible outcome is that the cars without handbrakes set will simply begin shoving the 20 cars with handbrakes set. In that case, you know the test has failed. But say that does not happen. Let’s say you release the air and nothing moves. If that happens, the test has not failed, but it has not passed either. The test is incomplete because there has been no adjustment of slack. So what can you do to either cause or allow the slack to adjust? You can’t do anything to allow it to adjust because it already is allowed to adjust and it is not adjusting. In order to allow slack to adjust, the train would have to be stretched on the down grade, so that releasing the air would allow the slack to run in against the 20 cars of handbrakes. So your only option is to cause slack to adjust. Your objective is to cause the slack to adjust in order to see if the 20 cars of handbrakes are still holding the train stationary after the slack adjusts. Just like with allowing slack to adjust, I don’t see how the slack can be caused to adjust with a bunched train facing down the grade and lead by 20 cars with handbrakes set. So I assume the procedure (i) could not be applied to this train because there is no way to allow or cause slack to adjust. I am not sure if you could do something with distributed power to change the slack so it could then be allowed to adjust. But with all the power on the head end, I do not see a method for Procedure (i). HAND BRAKE EFFECTIVNESS TEST PROCEDURE(ii) Say you are moving a train down grade and stopping with air, and when stopped, the air is holding the train with slack bunched. You set 20 handbrakes on the head end of the train. If you test with procedure (ii), after releasing the automatic brake, one possible outcome is that the cars without handbrakes set will simply begin shoving the 20 cars with handbrakes set. In that case, you know the test has failed. But if you release the air and nothing moves, the test has not failed, but it has not passed either. The test is incomplete. To complete the test, you must apply enough power to move the train, and then stop applying power and observe the train to stop moving. The rule does not specify which direction the train is to be moved in order to verify securement, so consider the results of pulling the train ahead for this part of the test. You apply power and the slack begins to stretch out in the leading 20 cars with handbrakes set. At some point as the slack stretches out in the first 20 cars, it will cease running out, and the remaining cars with handbrakes set will be shoved ahead by all of the cars behind them with no handbrakes set. So, the entire train will be moving down grade with slack stretched in the locomotive consist, and also stretched in some number of the leading portion of the 20 cars with handbrakes set. Trailing those leading cars with slack stretched will be cars with the slack bunched, and they will include all the remaining cars with handbrakes set plus the rest of the train with all brakes released. Then when the power is shut off, the train must stop moving, at which point some of the leading cars of the 20 cars with handbrakes set are likely to have slack stretched by the free-rolling locomotive consist pulling on them by the force of gravity; and all of the cars trailing those cars with slack stretched will have slack bunched. This effect is likely to result in fewer than 20 cars with handbrakes set actually holding the train in securement. When the locomotive began to pull on the train, it was stretching the slack in the 20 cars with handbrakes set. One by one, those cars began to move with their handbrakes dragging. As this process continued, each car caused to move was removed from the securement resistance that is holding all of the cars behind the 20 cars with handbrakes set. It is like removing bricks from a bridge support until the bridge falls down. As the cars with handbrakes set are one-by-one removed from securement, the securement finally fails when the falling number of cars in the securement reach a point where they are no longer able to hold back the train. Therefore, not only does this test tell you whether it passes or fails, it also provides the information that could tell you by how much it passes or fails. However, the test offers no way to capture this information For example, let’s say that the locomotive pulled the slack out of the first 10 cars of the 20 cars with handbrakes set. At that point the remaining ten cars with handbrakes set do not have enough braking resistance to hold the rest of the train. So all the rest of the train plus the trailing 10 cars with hand brakes set, would shove ahead with all their slack bunched. This would show that 20 cars with brakes set was exactly twice the number needed to hold the train with zero safety margin. So there were 10 extra cars with handbrakes constituting a safety margin. However, this data is not captured during the handbrake effectiveness test, so there is no way to know what the safety margin is with any given number of cars with handbrakes set and holding the train. So it is possible to pass the test with zero safety margin. Zero means that if a mosquito flaps its wings too hard when passing the 87th car, the train runs away. Yet the train passed the handbrake securement test. The Procedure (ii) also does not stipulate details such as which direction the power is to be applied in relation to the gradient. What if an engineer decided to test by applying power to move the train up-grade? That would pass the test for sure, but it would also cheat the test. When the power is applied and the train begins to move, the next step is to shut off power and see if the movement stops due to the resistance of the handbrakes that have been set. When you are moving the train up-grade, with some handbrakes set, and shut off power, gravity will aid the handbrakes in stopping the train. Now if the train is actually has insufficient handbrakes set, it will begin rolling forward immediately after stopping, and that would indicate that the handbrakes are insufficient. But the test is complete the instant the train stops after shutting off power, and if the independent brake were applied the instant the train stops, the test is complete, it passes, and the train is not secured because the test was flawed due to the aid of gravity in stopping the train which completed the test.
Euclid tree68 From current CROR Rule 112: (e) When hand brakes are used, an effectiveness test must be performed as follows: release all air brakes and, (i) allow or cause the slack to adjust. It must be apparent when slack runs in or out, that the hand brakes are sufficient to prevent the equipment from moving; or (ii) apply sufficient tractive effort to determine that the hand brakes provide sufficient force to prevent the equipment from moving when tractive effort is terminated. HAND BRAKE EFFECTIVNESS TEST PROCEDURE(i) Say you are moving a train down grade and stopping with air, and when stopped, the air is holding the train with slack bunched. You set 20 handbrakes on the head end of the train. If you test with procedure (i), the test is not completed unless an adjusting of slack occurs after releasing the automatic brake. You have the option of allowing or causing the slack to adjust, but the adjustment must occur in order to complete the test with procedure (i). When the air is released under procedure (i), one possible outcome is that the cars without handbrakes set will simply begin shoving the 20 cars with handbrakes set. In that case, you know the test has failed. But say that does not happen. Let’s say you release the air and nothing moves. If that happens, the test has not failed, but it has not passed either. The test is incomplete because there has been no adjustment of slack. So what can you do to either cause or allow the slack to adjust? You can’t do anything to allow it to adjust because it already is allowed to adjust and it is not adjusting. In order to allow slack to adjust, the train would have to be stretched on the down grade, so that releasing the air would allow the slack to run in against the 20 cars of handbrakes. So your only option is to cause slack to adjust. Your objective is to cause the slack to adjust in order to see if the 20 cars of handbrakes are still holding the train stationary after the slack adjusts. Just like with allowing slack to adjust, I don’t see how the slack can be caused to adjust with a bunched train facing down the grade and lead by 20 cars with handbrakes set. So I assume the procedure (i) could not be applied to this train because there is no way to allow or cause slack to adjust. I am not sure if you could do something with distributed power to change the slack so it could then be allowed to adjust. But with all the power on the head end, I do not see a method for Procedure (i).
tree68 From current CROR Rule 112: (e) When hand brakes are used, an effectiveness test must be performed as follows: release all air brakes and, (i) allow or cause the slack to adjust. It must be apparent when slack runs in or out, that the hand brakes are sufficient to prevent the equipment from moving; or (ii) apply sufficient tractive effort to determine that the hand brakes provide sufficient force to prevent the equipment from moving when tractive effort is terminated.
From current CROR Rule 112:
(e) When hand brakes are used, an effectiveness test must be performed as follows: release all air brakes and,
(i) allow or cause the slack to adjust. It must be apparent when slack runs in or out, that the hand brakes are sufficient to prevent the equipment from moving; or
(ii) apply sufficient tractive effort to determine that the hand brakes provide sufficient force to prevent the equipment from moving when tractive effort is terminated.
HAND BRAKE EFFECTIVNESS TEST PROCEDURE(i)
Say you are moving a train down grade and stopping with air, and when stopped, the air is holding the train with slack bunched. You set 20 handbrakes on the head end of the train.
If you test with procedure (i), the test is not completed unless an adjusting of slack occurs after releasing the automatic brake. You have the option of allowing or causing the slack to adjust, but the adjustment must occur in order to complete the test with procedure (i).
When the air is released under procedure (i), one possible outcome is that the cars without handbrakes set will simply begin shoving the 20 cars with handbrakes set. In that case, you know the test has failed. But say that does not happen. Let’s say you release the air and nothing moves. If that happens, the test has not failed, but it has not passed either. The test is incomplete because there has been no adjustment of slack. So what can you do to either cause or allow the slack to adjust?
You can’t do anything to allow it to adjust because it already is allowed to adjust and it is not adjusting. In order to allow slack to adjust, the train would have to be stretched on the down grade, so that releasing the air would allow the slack to run in against the 20 cars of handbrakes.
So your only option is to cause slack to adjust. Your objective is to cause the slack to adjust in order to see if the 20 cars of handbrakes are still holding the train stationary after the slack adjusts. Just like with allowing slack to adjust, I don’t see how the slack can be caused to adjust with a bunched train facing down the grade and lead by 20 cars with handbrakes set.
So I assume the procedure (i) could not be applied to this train because there is no way to allow or cause slack to adjust. I am not sure if you could do something with distributed power to change the slack so it could then be allowed to adjust. But with all the power on the head end, I do not see a method for Procedure (i).
HAND BRAKE EFFECTIVNESS TEST PROCEDURE(ii)
If you test with procedure (ii), after releasing the automatic brake, one possible outcome is that the cars without handbrakes set will simply begin shoving the 20 cars with handbrakes set. In that case, you know the test has failed. But if you release the air and nothing moves, the test has not failed, but it has not passed either. The test is incomplete.
To complete the test, you must apply enough power to move the train, and then stop applying power and observe the train to stop moving. The rule does not specify which direction the train is to be moved in order to verify securement, so consider the results of pulling the train ahead for this part of the test.
You apply power and the slack begins to stretch out in the leading 20 cars with handbrakes set. At some point as the slack stretches out in the first 20 cars, it will cease running out, and the remaining cars with handbrakes set will be shoved ahead by all of the cars behind them with no handbrakes set.
So, the entire train will be moving down grade with slack stretched in the locomotive consist, and also stretched in some number of the leading portion of the 20 cars with handbrakes set.
Trailing those leading cars with slack stretched will be cars with the slack bunched, and they will include all the remaining cars with handbrakes set plus the rest of the train with all brakes released.
Then when the power is shut off, the train must stop moving, at which point some of the leading cars of the 20 cars with handbrakes set are likely to have slack stretched by the free-rolling locomotive consist pulling on them by the force of gravity; and all of the cars trailing those cars with slack stretched will have slack bunched. This effect is likely to result in fewer than 20 cars with handbrakes set actually holding the train in securement.
When the locomotive began to pull on the train, it was stretching the slack in the 20 cars with handbrakes set. One by one, those cars began to move with their handbrakes dragging. As this process continued, each car caused to move was removed from the securement resistance that is holding all of the cars behind the 20 cars with handbrakes set. It is like removing bricks from a bridge support until the bridge falls down.
As the cars with handbrakes set are one-by-one removed from securement, the securement finally fails when the falling number of cars in the securement reach a point where they are no longer able to hold back the train.
Therefore, not only does this test tell you whether it passes or fails, it also provides the information that could tell you by how much it passes or fails. However, the test offers no way to capture this information
For example, let’s say that the locomotive pulled the slack out of the first 10 cars of the 20 cars with handbrakes set. At that point the remaining ten cars with handbrakes set do not have enough braking resistance to hold the rest of the train. So all the rest of the train plus the trailing 10 cars with hand brakes set, would shove ahead with all their slack bunched.
This would show that 20 cars with brakes set was exactly twice the number needed to hold the train with zero safety margin. So there were 10 extra cars with handbrakes constituting a safety margin.
However, this data is not captured during the handbrake effectiveness test, so there is no way to know what the safety margin is with any given number of cars with handbrakes set and holding the train. So it is possible to pass the test with zero safety margin. Zero means that if a mosquito flaps its wings too hard when passing the 87th car, the train runs away. Yet the train passed the handbrake securement test.
The Procedure (ii) also does not stipulate details such as which direction the power is to be applied in relation to the gradient. What if an engineer decided to test by applying power to move the train up-grade? That would pass the test for sure, but it would also cheat the test. When the power is applied and the train begins to move, the next step is to shut off power and see if the movement stops due to the resistance of the handbrakes that have been set.
When you are moving the train up-grade, with some handbrakes set, and shut off power, gravity will aid the handbrakes in stopping the train. Now if the train is actually has insufficient handbrakes set, it will begin rolling forward immediately after stopping, and that would indicate that the handbrakes are insufficient. But the test is complete the instant the train stops after shutting off power, and if the independent brake were applied the instant the train stops, the test is complete, it passes, and the train is not secured because the test was flawed due to the aid of gravity in stopping the train which completed the test.
Hello Tinkerbelle Rail - serving all of Neverland! Captain Hook was a brakeman that didn't secure his train.
jeffhergertYou would be great as a railroad manager. Twist your interpretations to fit your needs.
He has no practical railroad experience, so he has to work with how he thinks things work, which has proven in the past to have no basis in reality.
jeffhergertYou would be great as a railroad manager. Twist your interpretations to fit your needs. Jeff
I believe that is called rationalization on the part of the contributor. Reword things to fit your agenda.
Norm
You would be great as a railroad manager. Twist your interpretations to fit your needs.
Jeff
Even a perfect hand brake doesn't really lock the wheel - but it's enough to keep it from turning under most circumstances.
I've seen a car that was secured days or weeks earlier start rolling when bumped. In that case, a couple quick pulls on the hand brake was enough to take care of the problem.
So the question becomes at what grade the coefficient of friction between the shoe and the wheel is insufficient to hold a given car. Besides the grade, the major factor is how well the brake rigging is working. Clearly, a brake working at 100% of its designed function will hold a given car on a steeper grade than one that is not working properly. And that's already been mentioned.
A push/pull test is going to disturb the static state of a secured car, as noted in my example above. The question becomes when there are enough hand brakes properly set to hold even with that disturbance. Given variables of grade and brake effectiveness, it's possible that even 100% of the hand brakes would not be enough to hold the train, if disturbed.
You can easily demonstrate that by placing a hockey puck on a slanted board. There will be a range of angles where the puck won't move unless pushed, and at the opposite end a range of angles where the puck will always slide down. In between will be that range of angles where the puck will stay in place, until you push it, at which time it will slide down the board.
I have been thinking about the push/pull test as it is described in the post Lac Megantic Rule 112. I will post some thoughts and questions I have about it. I know it is nice to have rules be simple, but I think a lot more clarity could be of benefit the details of testing in Rule 112. If the testing is the critical pivot point between success and failure, it needs to be clearly described.
I am particularly interested in the choice of using procedure (i) versus (ii).
I hate duplicate posts.
But I have no alternative to a proper securement test on a heavy grade with a typical Westinghouse brake applied in emergency and 'normal' dynamics insufficient by themselves to hold the train from accelerating.
I wonder if there is an intermediate retainer setting that would set 'local' air-brake cylinder pressure on some cars in addition to handbrake set. You could then set some air (but not enough to slide) in cars toward the rear of the train and pull some of the head-end slack out of a downhill train before setting front-end handbrakes. Then you have some ability to reverse the consist against the supposedly secured train and then pull back downhill when you have to release and recharge the trainline ... or, as in the LIM case, can't reliably charge the trainline to pressure after releasing...
Not enough of a full answer. It does occur to me though that this kind of situation shows some of the great potential unsung advantages of graduated-release full-pressure-trainline ECP.
EuclidThey said that the push/pull test is unreliable in some circumstances.
Actually, they seem to be saying it is unreliable in ALL circumstances on high grades, without any further discussion or proof. The entire 'grade of interest' for the LIM train was over 2% (look carefully at the track chart) which I think qualifies as high grade, just as at Lac Megantic, and yes, this does raise some question about what a Canadian securement test on the Nantes grade would consist of. I do not recall this point being raised in testimony although it now seems more highly relevant to Harding's perceived action.
Seems to me a couple of railroaders discussed securement tests on high grades in one of the older Megantic threads. I would be thinking there would be some combination of downhill 'notch-up' testing followed by x number of 'reserve' additional brakes after the point at which the shoved train refused to move, but this does add some additional strength to the argument against securing unattended trains on the Nantes grade and the astoundingly small number of applied handbrakes Harding thought sufficient.
I have never been a "rail" so I can only base my thoughts on information that has been provided from the trial and not the speculation that is so prevelant on this forum.
Apperances indicate Hardin failed to do his job in compliance with best practices and regulations but until either is proven in court I will have to reserve judgement.
Like another poster here I can take a look back and say what I would have done in similar circumstances. Would that absolve me of responsibility if I failed to do my job regardlees of orders from a dispatcher? I doubt his orders would.
I, without further speculation, will wait to see what the jury concludes. I can, while thinking of the suffering of the citizens of Lac Megantic wait for the verdict.
OvermodUp to now I had not actually read through the linked report. I suggest you and Euclid do so; the only real 'question' is whether your eyes go wide before the hair stands up on the back of your neck.
Yes, I know it was a bad train. But it ran as a train and was handled and secured like as a train. The TSB investigated it and wrote a report. As unsual as the circumstances may have been, it prompted the TSB to write about one full page of commentary on the problems of train securment, including Rule 112. They said that the push/pull test is unreliable in some circumstances.
So, I think that those comments are highly pertinent to the Lac Megantic runaway.
BaltACDSomething is rotten in Denmark with your and the TSB description of the entire scenario.
Up to now I had not actually read through the linked report. I suggest you and Euclid do so; the only real 'question' is whether your eyes go wide before the hair stands up on the back of your neck.
For the record, this wasn't a QNS&L train, it was a LIM train. Just reading about the "preparation" of the cars involved is enough to start the worries. One of a number of smoking guns explaining this was the reported utter absence of brake or wheel wear on the runaway consist... including all 35 cars supposedly hand-braked; this despite peak downgrade quite substantial enough to generate brake-fade levels of shoe outgassing a la 17 Mileg Grade at far less than the 'developed' peak speed.
One conclusion, that I think is far likelier than not, was that none of the 35 'rebuilds' had functionally unstuck handbrake gear: the rust and hardened-at-minus-20-C lubricant remainder taking up the supposed 80lb exertion to apply handbrakes.
How you factor that kind of thing into a 'number-of-brakes' interpretation of 112, instead of an obvious and sensible version of pull testing, would be difficult to justify.
Sorry for getting off the 'trial' topic so extensively, as there was and is no real or legitimate justification for bringing up these specific problems at the Lac Megantic hearings.
Euclid daveklepper Are there known cases of the push-pul test havingbeen applied properly, but still a runaway happened? I don't know. The TSB says that testing is unreliable, and it appears to me that the new Rule 112 is not the outgrowth of the TSB conserns about testing being unreliable. The new rule is definitely the outgrowth of Lac Megantic. But in regard to the TSB's doubts about the push/pull test, they seemed most interested in replacing the test with more definitive rules that defined exactly how to secure the train rather than the current "estimate and test" method. With that new TSB vision, the QNSL runaway may not have happened, although that a sure bet. That was this case: In the QNSL runaway, the engineer discovered that the train was out of control, so he stopped with an emergency application. The tables called for a minimum of 12 handbrakes, but the engineer relied on his own mental model and set 35 handbrakes. I assume he intended to do a push/pull test, but before he got back to the engine, the train rolled away. The emergency application had leaked off of a sufficient number cylinders, so that the train was no longer held with 35 handbrakes. As it turned out, his mental model was wrong and 35 handbrakes was not enough to hold the train. As I recall, the TSB determined that it would have required 60 handbrakes. I wonder if there was time for the engineer to set 60 handbrakes before the air leaked off with too few handbrakes set to hold the train.
daveklepper Are there known cases of the push-pul test havingbeen applied properly, but still a runaway happened?
I don't know. The TSB says that testing is unreliable, and it appears to me that the new Rule 112 is not the outgrowth of the TSB conserns about testing being unreliable. The new rule is definitely the outgrowth of Lac Megantic. But in regard to the TSB's doubts about the push/pull test, they seemed most interested in replacing the test with more definitive rules that defined exactly how to secure the train rather than the current "estimate and test" method.
With that new TSB vision, the QNSL runaway may not have happened, although that a sure bet. That was this case:
In the QNSL runaway, the engineer discovered that the train was out of control, so he stopped with an emergency application. The tables called for a minimum of 12 handbrakes, but the engineer relied on his own mental model and set 35 handbrakes. I assume he intended to do a push/pull test, but before he got back to the engine, the train rolled away. The emergency application had leaked off of a sufficient number cylinders, so that the train was no longer held with 35 handbrakes.
As it turned out, his mental model was wrong and 35 handbrakes was not enough to hold the train. As I recall, the TSB determined that it would have required 60 handbrakes. I wonder if there was time for the engineer to set 60 handbrakes before the air leaked off with too few handbrakes set to hold the train.
Something is rotten in Denmark with your and the TSB description of the entire scenario.
tree68 BaltACD Company officials are required to perform a set number of Efficiency Tests every month, ... Conversely, our conductors and engineers are required to have at least one efficiency test each year. No getting lucky and not getting "caught." The challenge for us is that our volunteers are not scheduled, as such - arranging for a test when any given crew member is on duty can be a challenge.
BaltACD Company officials are required to perform a set number of Efficiency Tests every month, ...
Conversely, our conductors and engineers are required to have at least one efficiency test each year. No getting lucky and not getting "caught." The challenge for us is that our volunteers are not scheduled, as such - arranging for a test when any given crew member is on duty can be a challenge.
My carriers Conductors and Engineers were not volunteers, nor were any of the other employees that got Efficiency Tested. Having seen printouts of Efficiency Tests made - all testable employees were tested multiple times by multiple officials over the course of any year.
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