As I recall, and I'd have to look it up to be sure, but a service braking wave travels about 250 feet per second. An emergency application travels about 960 feet per second.
To control speed, UP stresses throttle modulation, dynamic braking and dynamic with automatic air braking. In that order. (Local instructions may override system instructions.) In the real world some times using the automatic brake first is the proper thing to do.
On trains over a certain size if you have to use air they prefer stopping before releasing the air. No running releases. Unless EMS - the computer - tells you to.
Jeff
blhanel jeffhergert There was no DP. The train wasn't very big, about 2/3 loads. When they came into view, just about the time they started to derail, the slack was definitely in from looking at the centerbeam flats. They have cushioned, long travel drawbars and there doesn't seem to be too much room between them. Someone in the chat at the time indicated that the train was a 10,000 footer. Derailed cars were only 20-30 back from the engines- still lots of inertia behind them.
jeffhergert There was no DP. The train wasn't very big, about 2/3 loads. When they came into view, just about the time they started to derail, the slack was definitely in from looking at the centerbeam flats. They have cushioned, long travel drawbars and there doesn't seem to be too much room between them.
There was no DP. The train wasn't very big, about 2/3 loads. When they came into view, just about the time they started to derail, the slack was definitely in from looking at the centerbeam flats. They have cushioned, long travel drawbars and there doesn't seem to be too much room between them.
Someone in the chat at the time indicated that the train was a 10,000 footer. Derailed cars were only 20-30 back from the engines- still lots of inertia behind them.
It only showed about 3700 feet out of Des Moines. And everything "set out" at a reporting location before SF Jct, but SF Jct shows a passing time about the same as the time stamp on the video. There was a pick up indicated in the KC complex that put it about 10000 feet leaving the KC area.
!0000 feet would seem more plausible for that to happen. And it wouldn't be the first time the system didn't have the correct car count (or even cars) shown. (For awhile, we were having trouble with one train coming off the BRC. Paperwork wouldn't match the train. One was so bad the FRA caught wind of it and wasn't happy.)
Train was MDMNL-01. No hyphen between the first letter (train type) and the station letter codes. That's more of a BNSF thing. Manifest, Des Moines to North Little Rock.
The train was M-DMNL taking the scenic route to get from the Spine Line to Neff Yard. There is no way to get from the Spine Line to access Neff Yard from the east, so the train was circling downtown Kansas City to enter Neff Yard from the west.
Euclid zugmann Euclid People are free to believe whatever they want. Of course they are. I just hope they exercise caution, esp with some of your, um, creative explanations of RR operations. There is nothing "creative" about my explanations. I follow the observable facts. There are a lot of explanations flying around here. Why aren't you warning people to be careful with all of those explanations? All I do is offer explanations for others to consider. There is nothing binding about them.
zugmann Euclid People are free to believe whatever they want. Of course they are. I just hope they exercise caution, esp with some of your, um, creative explanations of RR operations.
Euclid People are free to believe whatever they want.
Of course they are. I just hope they exercise caution, esp with some of your, um, creative explanations of RR operations.
There is nothing "creative" about my explanations. I follow the observable facts. There are a lot of explanations flying around here. Why aren't you warning people to be careful with all of those explanations? All I do is offer explanations for others to consider. There is nothing binding about them.
Your 'creative' explanations are right in there with QAnon Shaman for their validity.
Never too old to have a happy childhood!
you are about the only one I ever see on here that gives "definite" causes/reasons for whatever the issue of the week is.
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
EuclidPeople are free to believe whatever they want.
zugmann Euclid The cause of the derailment was the excessive buff force. That excessive buff force first caused the loud bang, and then it caused the derailment. Unless you have the downloads or were there to inspect it, or communicated with those that did - you can't really say that. I mean you can, but nobody should believe you.
Euclid The cause of the derailment was the excessive buff force. That excessive buff force first caused the loud bang, and then it caused the derailment.
Unless you have the downloads or were there to inspect it, or communicated with those that did - you can't really say that.
I mean you can, but nobody should believe you.
EuclidI understand why they adivse using dynamics as primary braking and automatic braking as last recourse. But it seems possible or even likely that this sudden surge in speed might have made this one of those last recourse situations. The advanatage of automatic braking here would have been that it sets up all through the train, as opposed to suddenly pinching down the speed with only locomotive braking. I would think this would have amounted to taking a very risky chance with the train descending a grade and passing though that relatively sharp curve.
While automatic use does propagate throughout the train - it does so sequentially starting from the head end - its propagation is not instantaneous. It's propagation does mimick the use of the independent to an extent unless the Engineer performs power braking and uses power to keep the slack stretched as the automatic is applying. There is no evidence of power braking being performed.
EuclidThe cause of the derailment was the excessive buff force. That excessive buff force first caused the loud bang, and then it caused the derailment.
It looked to me as if there was a small derailment of some of the leading cars in the consist -- off the rails only slightly, but upright -- and at least part of the initial bang might have been the rest of any slack from the already-bunched rear part of the consist colliding with the (rapidly increasing) resistance. The first and second centerbeams jackknife outward from compression, with the first swinging around just far enough to foul the track. The third centerbeam never derails; it comes neatly around the curve until it hits the end of the first, which strips off the truck and launches it up into the 'corner' of the bridge structure, where leverage takes it apart bay by bay in a kind of devil's CEM.
zugmann I didn't see/hear any violent run in or run outs on the camera - but maybe there was? Another guess I'll toss out in this guessfest: a slipped hi-lo coupling (or toher drawbar issue)? Drawbar was hanging a little low and was able to slip out when the slack ran in? Sure looked like the centerbeam was smack against the hopper before it hit the curve. Could also be that bang that was heard. --all just wild speculation.
I didn't see/hear any violent run in or run outs on the camera - but maybe there was?
Another guess I'll toss out in this guessfest: a slipped hi-lo coupling (or toher drawbar issue)? Drawbar was hanging a little low and was able to slip out when the slack ran in? Sure looked like the centerbeam was smack against the hopper before it hit the curve. Could also be that bang that was heard.
--all just wild speculation.
Good theory.
Still in training.
BaltACD Euclid JayBee The track is downhill in the direction the train is moving. The grade is slight but there. The curve has a low speed limit, perhaps the train was about to overspeed, so the crew applied eith the Independant brake or the Dynamics. They might have gotten away with it if the train had been further along and the Centerbeams were around the curve. I wonder what the speed limit is there. Why might they have chosen not to apply the automatic brake? When I was still working (2016) CSX was teaching Engineers to use Dynamic Braking as their primary braking method and to basically use the automatic air brake system as the brake of last recourse. I have no idea if this is UP's view on the subject.
Euclid JayBee The track is downhill in the direction the train is moving. The grade is slight but there. The curve has a low speed limit, perhaps the train was about to overspeed, so the crew applied eith the Independant brake or the Dynamics. They might have gotten away with it if the train had been further along and the Centerbeams were around the curve. I wonder what the speed limit is there. Why might they have chosen not to apply the automatic brake?
JayBee The track is downhill in the direction the train is moving. The grade is slight but there. The curve has a low speed limit, perhaps the train was about to overspeed, so the crew applied eith the Independant brake or the Dynamics. They might have gotten away with it if the train had been further along and the Centerbeams were around the curve.
The track is downhill in the direction the train is moving. The grade is slight but there. The curve has a low speed limit, perhaps the train was about to overspeed, so the crew applied eith the Independant brake or the Dynamics. They might have gotten away with it if the train had been further along and the Centerbeams were around the curve.
I wonder what the speed limit is there. Why might they have chosen not to apply the automatic brake?
When I was still working (2016) CSX was teaching Engineers to use Dynamic Braking as their primary braking method and to basically use the automatic air brake system as the brake of last recourse. I have no idea if this is UP's view on the subject.
I understand why they adivse using dynamics as primary braking and automatic braking as last recourse. But it seems possible or even likely that this sudden surge in speed might have made this one of those last recourse situations. The advanatage of automatic braking here would have been that it sets up all through the train, as opposed to suddenly pinching down the speed with only locomotive braking. I would think this would have amounted to taking a very risky chance with the train descending a grade and passing though that relatively sharp curve.
ZUG, sounds reasonable to me.
Additional we don't know if the train was being operated by Leader/Trip Optimizer operation - we do know that the Class 1's are 'pushing' this method of train operation in most cases. Further, it hasn't been stated - Is PTC in effect on this particuar segment of track? Questions, Questions, Questions?
I think that's key. Not sure what caused the intial derailment (probably too much independent or dynamic, I'm guessing, to cause violent run-in on that grade), but the fact that the leading part of the train went into full emergency before the huge trailing part could is the reason there was so much force to keep wreaking havoc.
I'm guessing they're going to put this squarely on the engineer, unless some car or rail defect is discovered.
Bridges sure can withstand a lot of impact.
The track is downhill in the direction the train is moving. The grade is slight but there. The curve has a low speed limit, perhaps the train was about to overspeed, so the crew applied either the Independant brake or the Dynamics. They might have gotten away with it if the train had been further along and the Centerbeams were around the curve.
I wonder what caused the excess buff force. It looked to me as though the train sped up after the engines passed the grade crossing. Very soon after, the train seemed to slow and there was the loud bang and a little noise from draft gear indicating possibly an increase in braking from the head end and a corresponding rise in buff force. And that was just too much buff force to successfully negotiate that curve.
Lithonia Operator tree68 diningcar I believe grades are insignificant at SF Jct. I have been there, but years ago. It doesn't take much. That said, there was a lot of momentum there in the tail end of the train. We never see that end, but I think there were three engines leading, which might indicate a good sized train. In theory, the rear of the train was in emergency once the first couplers parted, yet that portion of the train certainly kept moving. I'm wondering if the independent was applied, which would certainly cause a slack run-in. One of these days, the facts will filter out and maybe we'll find out what the actual cause was. I thought that when the air hoses part the ENTIRE train goes into emergency. No?
tree68 diningcar I believe grades are insignificant at SF Jct. I have been there, but years ago. It doesn't take much. That said, there was a lot of momentum there in the tail end of the train. We never see that end, but I think there were three engines leading, which might indicate a good sized train. In theory, the rear of the train was in emergency once the first couplers parted, yet that portion of the train certainly kept moving. I'm wondering if the independent was applied, which would certainly cause a slack run-in. One of these days, the facts will filter out and maybe we'll find out what the actual cause was.
diningcar I believe grades are insignificant at SF Jct. I have been there, but years ago.
I believe grades are insignificant at SF Jct. I have been there, but years ago.
It doesn't take much.
That said, there was a lot of momentum there in the tail end of the train. We never see that end, but I think there were three engines leading, which might indicate a good sized train.
In theory, the rear of the train was in emergency once the first couplers parted, yet that portion of the train certainly kept moving.
I'm wondering if the independent was applied, which would certainly cause a slack run-in.
One of these days, the facts will filter out and maybe we'll find out what the actual cause was.
I thought that when the air hoses part the ENTIRE train goes into emergency. No?
Trains do go into emergency when the air hoses part in the trainline, however, that emergency 'pulse' propagates through the train at the speed of sound (approximately) as opposed to the speed of light. Additionally, both parts of the parted train have the momentum of their mass to get stopped. Thousands of tons do not stop instantly. What happened once the trainline parted is exactly what one would expect as the mass of the rear of the train stopped itself in the pile up of the deriled cars.
Brian (IA) http://blhanel.rrpicturearchives.net.
Correct, LO, but that still takes time to work it's way through the brake lines.
It certainly looks like the back of the train's force was the cause, as opposed to a rail defect or car defect.
Switching from the train to the bridge, at 17:10 in the compiled video, there is a (IMHO) a significant deformation of the vertical support leg of the structure. Shown as the inpecting crew holds a straight edge
I wonder whether it will be replaced, shored up, or augmented in some way.
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...
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