Paul of Covington I have a question distantly related to this subject. If you are driving down a street at 35 MPH and at an intersection 150 feet ahead the light turns from green to yellow, how many pounds of force would you apply to the brake pedal to stop at that intersection?
I have a question distantly related to this subject. If you are driving down a street at 35 MPH and at an intersection 150 feet ahead the light turns from green to yellow, how many pounds of force would you apply to the brake pedal to stop at that intersection?
Zero. Minimum yellow time for a 35 MPH road is 3.6 seconds. In 3.6 seconds, my 35 MPH vehicle travels 36 feet past the limit line. More of a risk in making the "hard stop" under those conditions.
They are going to need a better brake wheel-winch machine. Controlling wheel torque will not be enough. They will have to measure brake shoe pressure. You turn the wheel until an indicator says the job is done.
What, a ground pounder is not required to carry a torque wrench along with the knuckle that he carries?
Johnny
"hand-brake torque (Appendix B). When this table is used for LIM-55, according to a torque of 80 foot-pounds on an average grade of 1.3%, 57 hand brakes would be necessary to secure the train between Bybee and Tika."
I'd like to see the ground pounder with the torque wrench.
Disk or Drum Brakes? If drum, are the shoes in proper adjustment?Brakes at operating temperature or cold?What type of friction material on the brake pad or shoe?Power assisted or unassisted brake system?What is the condition of the tires on the vehicle?What is the grade where braking is taking place?What is the condition of the surface that braking is taking place on? Dry asphalt? Wet asphalt? Are there asphalt 'waves' in the braking area? Dry smooth concrete? Wet smooth concrete? Dry textured concrete? Wet textured concrete? Lose dirt? Wet lose dirt = mud? Oiled dirt? Wet oiled dirt? Lose gravel? Wet lose gravel? Is the gravel round river run or jagged multisurface aggregrate? Is there snow on the above listed surfaces? Is there ice covering the above listed surfaces?Each of the items listed have varying coefficients of friction and thus alter stopping distance.
You brake as hard or as lightly as required to effect the stop - if you are attempting to stop on a downgrade surface that is covered by glare ice, you are going too fast for the surface and most likely will not get stopped, and if the downgrade is steep enough, the vehicle 'if stopped' would slide down the ice with wheels locked stationary.
Just like applying hand brake - you do what is necessary to achieve the desired result - there is no single number.
Never too old to have a happy childhood!
Unless, as Jeff says......
Many people would see the light changing to yellow as an indication to speed up, not to stop at the intersection.
Jeff
cleaned up
Thanks to Chris / CopCarSS for my avatar.
tree68 Bucyrus Regarding the “right answer” to the question of how many handbrakes are necessary, semantics enter into the answer. Both of the following conflicting answers are true: 1) There is no “magic number” or accurate rule of thumb, guideline, chart of information, or accurate means to calculate the proper number of handbrakes required. Under those terms, it is impossible to know the number, so it is accurate to say that there is no number. Not entirely true - the way to determine the number of handbrakes necessary is to test. I would suggest that your statement be changed to read "...it is accurate to say there is no predetermined number for a given situation." That there are guidelines in the rules/timetables says that as the result of experience/testing/scientific calculation, the number has been determined - so there is a number. 2) There is a specific minimum number of brakes necessary. One less than the minimum, is too few. This statement is true. Once again, however, determining what that minumum number is is best done by testing.
Bucyrus Regarding the “right answer” to the question of how many handbrakes are necessary, semantics enter into the answer. Both of the following conflicting answers are true: 1) There is no “magic number” or accurate rule of thumb, guideline, chart of information, or accurate means to calculate the proper number of handbrakes required. Under those terms, it is impossible to know the number, so it is accurate to say that there is no number.
Regarding the “right answer” to the question of how many handbrakes are necessary, semantics enter into the answer. Both of the following conflicting answers are true:
1) There is no “magic number” or accurate rule of thumb, guideline, chart of information, or accurate means to calculate the proper number of handbrakes required. Under those terms, it is impossible to know the number, so it is accurate to say that there is no number.
Not entirely true - the way to determine the number of handbrakes necessary is to test. I would suggest that your statement be changed to read "...it is accurate to say there is no predetermined number for a given situation." That there are guidelines in the rules/timetables says that as the result of experience/testing/scientific calculation, the number has been determined - so there is a number.
2) There is a specific minimum number of brakes necessary. One less than the minimum, is too few.
This statement is true. Once again, however, determining what that minumum number is is best done by testing.
I agree that the test is intended provide the required information to know the minimum number of handbrakes needed, but my item #1 was meant to exclude the test. That is why I stipulated “Under those terms, it is impossible to know the number.”
My item #2 requires the test.
I made the distinction between item #1 and #2 because it seemed to be the basis of considerable disagreement here yesterday. My point is that two conflicting interpetations are true.
But looking only at the push-pull test:
Paul North’s previous post brings up several questions that could cause the results of the push-pull test to vary. Also, the Canadian TSB states that the test is unreliable in mountain grade conditions. And to reinforce their viewpoint on that, they are immediately making the need for the push-pull test obsolete for trains handling dangerous cargo.
They stated their finding that the push-pull test was unreliable in 2009. They said that when using the push-pull test in mountain territory, it was impossible to determine whether the amount of handbrakes set complied with the company’s requirement that the number be sufficient to prevent the train from rolling with air brakes released.
_____________
"A stranger's just a friend you ain't met yet." --- Dave Gardner
The converse to your statement could be that one more than the minumum is too many, but I would opine that most here would agree that setting even one extra brake would be a good thing as it would provide some redundancy. If a crewmember sets an extra brake or two, this will not show up in the testing, as the train will react as desired.
This doesn't have to be a scientific study. The procedure is there - set the number of brakes specified in the rules/timetable and test. If it holds, you're good. Maybe you set 11 and only seven were actually necessary.
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...
In the runaway of QNS&L train number LIM-55, described in the link I posted above, the guidelines called for 12 handbrakes. The engineer, using his own discretion, applied 35 handbrakes, and the train ran away before he got back to the cab. Another guideline called for 57 handbrakes on that train.
Quote from the report (my emphasis in red):
If a train stops on the descending grade between Bybee and Tika following an emergency brake application, it must be secured in accordance with CROR Rule 112. That rule states that a sufficient number of hand brakes must be applied to ensure that the train is secured. Rule 112 special instructions specify the minimum number of hand brakes to be applied under general operating conditions, but do not give a number when specific conditions apply. It is left to the locomotive engineer's discretion to determine if additional hand brakes are required while taking into account such factors as train weight, track grade and braking force. In this occurrence, for LIM-55, consisting of 112 cars, the minimum number of hand brakes required by Rule 112 was 12 (Appendix A); however, the locomotive engineer indicated having applied 35 hand brakes on LIM-55 after taking the track profile and train specifications into consideration.
As a result of testing performed following the 1996 Edson, Alberta, accident (TSB report R96C0172), a table was established to provide the necessary number of hand brakes required to secure 100 loaded cars according to the track grade and hand-brake torque (Appendix B). When this table is used for LIM-55, according to a torque of 80 foot-pounds on an average grade of 1.3%, 57 hand brakes would be necessary to secure the train between Bybee and Tika. Similarly, in the Rockies, on such grades, Canadian Pacific Railway's special instructions require that half the hand brakes be applied on a train with similar characteristics as LIM-55.
schlimmthat really begs the question. there should be a consensus as to a guideline that takes into account tonnage, grade, etc. Otherwise you have folks just guessing how many to set initially and then testing and if that doesn't hold, go back out and set more?
If the entire railroad is on the same gradient, then one "standard" will do. But railroads vary. Is it necessary to set 25-30 handbrakes if the train is sitting at the center of a "bowl?" In that case, one handbrake might well be enough, since the train can't "roll out" to anywhere - it's already at the bottom of the hills.
Considering all the variables, experience is going to provide the rationale for how many handbrakes will be set under "normal" circumstances, and that's going in the rulebook. Also going into the rulebook (or timetable) is going to be special instructions for special situations, like significant grades.
Which is pretty much what you said:
The whole point of a guideline is to give a pretty accurate number that is then subject to testing. It is not an absolute nor intended to be.
What seems to be in question here is what that appropriate number is, and that's going to vary from railroad to railroad, and even division to division. Guidance for the CSX "Water Level Route" (Chicago Line) is going to be different from what is necessary in the hills of West Virginia.
Bottom line: There is not, nor can there be, an all encompassing standard that will fit all railroads all the time. Even if there is one, unless it is to set all the hand brakes on the train, there are variables that will come into play, most of which have already been mentioned here.
jeffhergert On our railroad, all these numbers and percentages came about after a roll-out of equipment out west about 10 years ago. In that case a road crew fouled up because they were under the impression that a yard crew was going to immediately couple into a cut of cars they had set out. Before that, the required amount was a "sufficient number" and we didn't have to release the air to see if they held. The instructions have changed over time. The first ones issued were overkill, a knee-jerk reaction to an event and have become more realistic over time. Jeff
On our railroad, all these numbers and percentages came about after a roll-out of equipment out west about 10 years ago. In that case a road crew fouled up because they were under the impression that a yard crew was going to immediately couple into a cut of cars they had set out. Before that, the required amount was a "sufficient number" and we didn't have to release the air to see if they held. The instructions have changed over time. The first ones issued were overkill, a knee-jerk reaction to an event and have become more realistic over time.
As usual, Jeff, you give a thoughtful answer to what is a serious question. The procedures have evolved on your railroad (UP) . Having a more clear guideline as to what is required than just "sufficient" would seem to take some (not all) of the trial and error approach out of the process.
C&NW, CA&E, MILW, CGW and IC fan
jeffhergertBefore that, the required amount was a "sufficient number" and we didn't have to release the air to see if they held. The instructions have changed over time. The first ones issued were overkill, a knee-jerk reaction to an event and have become more realistic over time.
jeffhergertMy railroad does issue guidelines and minimums to set. But they are just that, guidelines and minimums. That's why they still use the phrase "a sufficient number."
Jeff,
Are you are saying that “required amount” and “sufficient number” are two different things, but they have been sometimes interpreted to mean the same thing?
My railroad does issue guidelines and minimums to set. But they are just that, guidelines and minimums. That's why they still use the phrase "a sufficient number."
At a minimum, when leaving unattended cars, detached from a train, a minimum of 10% of the cars (and a further minimum of at least 5 cars) must have hand brakes tied. If leaving a train with the engines attached, hand brakes on all the engines (lead consist only) and 5 cars is required. If the engines are removed, then the 10% instructions kick in.
Guess what. Those instructions will hold a train in some places, but not in others. Even in places where there is no question the minimums will hold a train, you still have to release the air brakes to make sure the hand brakes hold.
To muddy the waters some, up until changes were made one area on my railroad (each superintendent issues the site specific instructions for his/her area) didn't always count one hand brake as equaling one car. Never mind figuring our platforms on articulated well cars, we're talking single, four axle cars here. Some hand brakes work the brake rigging of the entire car. When you turn the wheel it sets the brakes on both trucks. Others just work one truck on the end the wheel is located. That area counted those types as half a car. You not only had to figure how many cars by percentage instructions, but then check the types of hand brakes equipment on the cars. If you had 100 cars and needed to set brakes on 10% of the cars, how many hand brakes would you apply? You can't answer that under those instructions sitting in a cab or at a computer. You could say 10, but that wouldn't always be correct. It could be as many as 20 and you wouldn't know until you started tying brakes.
tree68I would opine that there is consensus - and that is that there is no "right" answer that can be provided by quoting a certain number of brakes to be set.
that really begs the question. there should be a consensus as to a guideline that takes into account tonnage, grade, etc. Otherwise you have folks just guessing how many to set initially and then testing and if that doesn't hold, go back out and set more? Frankly, that sounds ridiculous. The whole point of a guideline is to give a pretty accurate number that is then subject to testing. It is not an absolute nor intended to be. but the folks on here do not agree on an approximate number nor do the railroads agree on a guideline.
schlimmMore to the bigger point, it is not very reassuring that the folks with lots of real experience don't have more consensus.
I would opine that there is consensus - and that is that there is no "right" answer that can be provided by quoting a certain number of brakes to be set.
Further, the right answer (ie, specific number of brakes to set) today may be the wrong answer tomorrow.
The closest we're going to come is "enough to hold the train." Beyond that, it comes down to how to determine that number, and the procedures exist to test that.
Murphy Siding If there are this many amswers, to what is being presented as a simple questions, then perhaps the amswers are opinions. As such, wouldn't the opinions of those in the railroad business on a day to day basis seem to carry more weight than those who have simply tied down a lot of brakes in an undisclosed situation?
More to the bigger point, it is not very reassuring that the folks with lots of real experience don't have more consensus.
Murphy Siding schlimm It seems pretty obvious that this has turned into a personal argument between Bucyrus and several others who seem to think the only folks in a position to make decisions about how many handbrakes to set are those who do it. And the usual game is taking place, to get the moderators to lock it. In the case of this rail accident where 50 people lost their lives through no fault of their own except being nearby, both the railroad and the engineer failed the test. I disagree in your assesment. It's pretty obvious that this has turned into a thread like many we have seen before. Bucyrus asks a question. People in the know answer the question. (One of this forum's wonderful features.) Bucyrus says "no- that's not the answer. Bucyrus keeps asking the question. Bucyrus never gets the *right* answer. Bucyrus answers his own question. Bucyrus says it must be the correct answer, because he provided it. Others question Bucyrus' conclusion. Bucyrus insinuates (whether he perceives it or not) that railroad workers don't know as much about railroading as he does- because they never gave the *right* answer. And the beat goes on, and the beat goes on.
schlimm It seems pretty obvious that this has turned into a personal argument between Bucyrus and several others who seem to think the only folks in a position to make decisions about how many handbrakes to set are those who do it. And the usual game is taking place, to get the moderators to lock it. In the case of this rail accident where 50 people lost their lives through no fault of their own except being nearby, both the railroad and the engineer failed the test.
It seems pretty obvious that this has turned into a personal argument between Bucyrus and several others who seem to think the only folks in a position to make decisions about how many handbrakes to set are those who do it. And the usual game is taking place, to get the moderators to lock it.
In the case of this rail accident where 50 people lost their lives through no fault of their own except being nearby, both the railroad and the engineer failed the test.
It took 42 years and about a dozen job qualifications to get thru Railroading 101 from The U.ofSP&UP, but here I (and we) are taking Railroading 101.1
As as(s)uming as this is, here are some answers:
How many? Tonnage (at specified locations, or per cent of grade if knowledge of, if given or available) divided to get units of 300 tons times the percent of grade result. brakes to be set. At specified territories, specific numbers of set hand brakes, likely approved by the Legal Department, are required but no employe (SPsp) is free from empirical proof that the number was insufficient.
How hard to set them? Controlling kicked cars to a spot, a joint or just in the clear with the hand brake tells you, palm of the gloved hand and exercised biceps will tell you when the wheels lock up and____slide, like ice skates. Not good for a gradually releasing,leaking-off, air brake system unattended. Between moderate and severe grades, a lot but not all, energy on the brake's lever or wheel is best....the car's hand brakes are useless if when bumped into motion, they slide their wheels....
If there's evidence that Canada's TSB is populated with investigators that haven't or have set in their careers' handbrakes, pls bring it on. If one is found to suggest that a search for criteria judging the most likely principles of ti,,,,the causes of slaughter, accident, disaster, miss-happening, or.....they would get a ("liddl') bit off, they are justified asking about it.
Here is the TSB of Canada report on the QNS&L ore train that ran away after the engineer secured it with handbrakes. This is the runaway mentioned in the article I linked to the original post of this thread. The train ran away for 15 miles and attained 63 mph, but stopped without derailing or injuring anyone.
It discusses a lot of detail about issues with the air brakes that ultimately culminated with the engineer dynamiting the train when it got out of control. Then he had to set lots of handbrakes. As he was walking back to the engine, the train started to roll before the reservoirs had time to charge. From there, the train ran away. Many hand brakes were found to apply inadequate brake shoe force even though the wheel was wound adequately tight.
http://www.bst-tsb.gc.ca/eng/rapports-reports/rail/2011/r11q0056/r11q0056.asp
I posted before on the Megantic thread, my memory is that in 1953-1953, standard proceedure for securing a train on the B&M was to set 20% of car handbrakes plus the locomotive(s) on level track but ALL the handbrakes on a grade, then release the brakes and shut down the loco No push-pull test!
Murphy SidingIt's pretty obvious that this has turned into a thread like many we have seen before. Bucyrus asks a question. People in the know answer the question. (One of this forum's wonderful features.) Bucyrus says "no- that's not the answer. Bucyrus keeps asking the question. Bucyrus never gets the *right* answer. Bucyrus answers his own question. Bucyrus says it must be the correct answer, because he provided it. Others question Bucyrus' conclusion. Bucyrus insinuates (whether he perceives it or not) that railroad workers don't know as much about railroading as he does- because they never gave the *right* answer. And the beat goes on, and the beat goes on.
The only beat that goes on is you seeing a pattern that you want to see. “People in the know” gave different answers to the same question. Then when I questioned their answers, they got mad at me because they thought I did not agree with them. I suggest you go back and actually read and understand the thread before you jump to your standard conclusion about me not respecting “people in the know.”
Your idea of what I am insinuating is your own illusion because you have selected certain people that assume are correct all the time. Maybe that works for you, but I have never known anybody who I thought was correct all the time. Sorting that out is kind of what I thought this forum discussion was for. You make it seem like a clique.
zugmann Bucyrus No I did not miss his answer at all. But his answer is incorrect. The engineer faces all those variables and yet he must make the decision as to how many handbrakes to apply. He is not permitted to dodge his responsibility because he thinks there are too many variables. You are full within your right to think my answer is incorrect. Just like you are full within your rights to not disclose what capacity you dealt with handbrakes. And in a similar vein I am well within my rights to dodge my responsibility (although I have none to answer questions on this forum) to give you a detailed answer. This is my last answer to ANY of your questions. I wouldn't be surprised if others followed suit. It was a nice run. But I think this little dance has come to an end.
Bucyrus No I did not miss his answer at all. But his answer is incorrect. The engineer faces all those variables and yet he must make the decision as to how many handbrakes to apply. He is not permitted to dodge his responsibility because he thinks there are too many variables.
No I did not miss his answer at all. But his answer is incorrect. The engineer faces all those variables and yet he must make the decision as to how many handbrakes to apply. He is not permitted to dodge his responsibility because he thinks there are too many variables.
You are full within your right to think my answer is incorrect. Just like you are full within your rights to not disclose what capacity you dealt with handbrakes.
And in a similar vein I am well within my rights to dodge my responsibility (although I have none to answer questions on this forum) to give you a detailed answer.
This is my last answer to ANY of your questions. I wouldn't be surprised if others followed suit.
It was a nice run. But I think this little dance has come to an end.
Zugmann,
When I said, “He is not permitted to dodge his responsibility because he thinks there are too many variables,” I was referring to the engineer of the oil train, not to you. But I can see that it could be interpreted either way. I don’t consider you to be dodging any responsibility.
Paul_D_North_Jr See Sections 1.14.2 - Net Braking Ratios, 1.7 - Brake Shoes and Friction Fade, 2.7 - Braking Capacity, and 4.3.1 - Safety Concern - Performance Standards for Composition Brake Shoes, of the TSB report on the 29 June 2006 CN (ex-BCR) runaway and derailment, at: http://www.tsb.gc.ca/eng/rapports-reports/rail/2006/r06v0136/r06v0136.asp#1 These sections detail the various differences in the amount of retarding force required from each brake shoe, the causes of each, and how those standards has evolved. In particular, Section 1.14.2 - Net Braking Ratios states that each car is required to provide a braking force of at least 8.5% = 0.085 (1 / 12th) of the car's weight. For a 72-car train on a 1.2% grade, the gravity force downgrade is the equivalent of 0.864 cars (ignoring static resistance to rolling, and the weight and braking effect of the locomotives). At 0.085 of a car's weight for each car's brakes, to develop 0.87 cars' worth of resistance would require a little over 10 - say, 11 cars - to have their handbrakes applied. Most importantly, note that there is NO Factor or Margin of Safety in these calculations or this resulting number. Even just 1 of those 11 cars without brakes fully and effectively applied would be enough to allow that train to start rolling. Practically, I would suggest a factor of safety of at least 1.5 to 2.0, which would require from 16 to 22 cars to be 'tied down'. That goes to the result of the "test": What is a successful test ? When all of the wheels slide as the locomotive tugs downhill ? How long/ far after the locomotive stops pulling must the train have come to a halt ? A short time/ distance would correspond to a high factor of safety; a longer time/ distance - or no set standard - would be associated with a marginal number of brakes set, right on the edge of being just barely enough, or just a couple brakes too little. Even a train that has a barely adequate number of brakes applied may be deemed to have "enough", even though it is right on the edge of being uncontrollable. - Paul North.
See Sections 1.14.2 - Net Braking Ratios, 1.7 - Brake Shoes and Friction Fade, 2.7 - Braking Capacity, and 4.3.1 - Safety Concern - Performance Standards for Composition Brake Shoes, of the TSB report on the 29 June 2006 CN (ex-BCR) runaway and derailment, at: http://www.tsb.gc.ca/eng/rapports-reports/rail/2006/r06v0136/r06v0136.asp#1 These sections detail the various differences in the amount of retarding force required from each brake shoe, the causes of each, and how those standards has evolved.
In particular, Section 1.14.2 - Net Braking Ratios states that each car is required to provide a braking force of at least 8.5% = 0.085 (1 / 12th) of the car's weight.
For a 72-car train on a 1.2% grade, the gravity force downgrade is the equivalent of 0.864 cars (ignoring static resistance to rolling, and the weight and braking effect of the locomotives). At 0.085 of a car's weight for each car's brakes, to develop 0.87 cars' worth of resistance would require a little over 10 - say, 11 cars - to have their handbrakes applied.
Most importantly, note that there is NO Factor or Margin of Safety in these calculations or this resulting number. Even just 1 of those 11 cars without brakes fully and effectively applied would be enough to allow that train to start rolling. Practically, I would suggest a factor of safety of at least 1.5 to 2.0, which would require from 16 to 22 cars to be 'tied down'.
That goes to the result of the "test": What is a successful test ? When all of the wheels slide as the locomotive tugs downhill ? How long/ far after the locomotive stops pulling must the train have come to a halt ? A short time/ distance would correspond to a high factor of safety; a longer time/ distance - or no set standard - would be associated with a marginal number of brakes set, right on the edge of being just barely enough, or just a couple brakes too little. Even a train that has a barely adequate number of brakes applied may be deemed to have "enough", even though it is right on the edge of being uncontrollable.
- Paul North.
Paul,
You make some interesting points about the interpretation of the push-pull test. Those variables must be part of the reason why the TSB has decided that the push-pull test is unreliable. If they are correct, what does this mean in light of the fact that this has been standard routine in North American practice for so long? If the procedure is flawed, has it just been a matter of luck and good judgment that it works so often?
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