7j43k, I got this site up on Google Earth and it seems the original curve has been modified to a less sharper curve from the original construction; but does not appear to be recent. Visually my eye says the train had exited the curve before derailing. But of course there may be a different analysis by the NTSB inspection.
I don’t understand that either. My understanding is that a brake application propagates through the train at about the speed of sound. And each car has a vent valve to help speed the propagation of an emergency application through the train. So the last car should have been emergency long before 15 seconds, even on a relatively long consist like the Auto-Train. We don’t use EOT on our RR, so maybe there is something there I am not aware of.
With that small of a train, you probably couldn’t even get your hand from the automatic brake handle to the EOT dump switch before the rear end was at 0.
Now hitting it is a good reflex (just in case something got crimped off), but I think the NTSB was really reaching on that one.
Facts are Facts.
According to the event recorder information, the engineer initiated a service brake application at 5:07:57 p.m. He initiated an emergency brake application at the head end of the train at 5:08:01 p.m. By 5:08:02 p.m., the trainline pressure at the head of the train was 98 psi, the rear-end trainline pressure was 108 psi, and the train speed was 55 mph. At 5:08:04 p.m., the trainline pressure at the head of the train was zero and the rear-end trainline pressure was 108 psi. At 5:08:05 p.m., the pressure at the rear of the train dropped 2 psi to 106 psi and remained at 106 psi for 7 seconds. At 5:08:11 p.m., the EOT went into emergency. The trainline pressure at the rear end dropped to zero at 5:08:12 p.m. At 5:08:15, the engineer activated the EOT device. (See appendix E for more detailed event recorder information.
And after reading the Autotrain report, I looks very much like a similar case except the track failure may have occurred after the engines pased over it. Has any loco video been released?
7j43k, I got this site up on Google Earth and it seems the original curve has been modified to a less sharper curve from the original construction; but does not appear to be recent. Visually my eye says the train had exited the curve before derailing. But of course there may be a different analysis by the NTSB inspection.
[quote user=“Electroliner 1935”]
adkrr64
Lithonia OperatorI don’t get it. It says the engineer waited about 15 seconds (after going into emergency) before pinging the EOT. It was a forty-car train, and I would have thought that the entire train would have been at full braking within about five seconds after going into emergency in the cab. Not so?
I don’t understand that either. My understanding is that a brake application propagates through the train at about the speed of sound. And each car has a vent valve to help speed the propagation of an emergency application through the train. So the last car should have been emergency long before 15 seconds, even on a relatively long consist like the Auto-Train. We don’t use EOT on our RR, so maybe there is something there I am not aware of.
Facts are Facts.
According to the event recorder information, the engineer initiated a service brake application at 5:07:57 p.m. He initiated an emergency brake application at the head end of the train at 5:08:01 p.m. By 5:08:02 p.m., the trainline pressure at the head of the train was 98 psi, the rear-end trainline pressure was 108 psi, and the train speed was 55 mph. At 5:08:04 p.m., the trainline pressure at the head of the train was zero and the rear-end trainline pressure was 108 psi. At 5:08:05 p.m., the pressure at the rear of the train dropped 2 psi to 106 psi and remained at 106 psi for 7 seconds. At 5:08:11 p.m., the EOT went into emergency. The trainline pressure at the rear end dropped to zero at 5:08:12 p.m. At 5:08:15, the engineer activated the EOT device. (See appendix E for more detailed event recorder information.
An
Passenger brakes on the passenger cars. Lousy tread brakes and probably no graduated release on a great many top-heavy car-carrying freight cars. We have those here who can tell what braking a train like that under emergency conditions,
You ahve to remember - what the head end is reporting is not always what the EOT is actually at. Sometimes there’s delay or even non-communication between the two. So the rear end may have been already at zero before it showed as zero on the head end. Just going by what the head end says isn’t always 100% accurate.
As I said in my first post on this thread, some of those reports are very educational, and I think that this one (RAR0302) is near the top of the list in that category. It reminded me of some of the Henry Petroski books of engineering history.
Both straight track and curved track can convert the sun kink rail stress into sideways relief. Sideways relief from either straight or curved track can derail the train if the relief disruption is large enough.
The relief causing track misalignment can occur either before a train reaches the track heat stress zone, or it can be initiated when the train enters the zone.
There is no specific ambient temperature threshold above which heat or sun kinks occur because while ambient temperature contributes to the cause, it is not the only contributing factor.
From this link:
https://www.whsv.com/2021/09/27/safety-officials-seek-answers-deadly-amtrak-derailment/
Temperatures were in the high 80s Saturday near Joplin, according to the National Weather Service.
Russ Quimby, a former rail-accident investigator for the NTSB, said heat is the most likely explanation. He is convinced because the locomotives in front did not derail, but eight lighter coach cars behind them did.
“This has all the earmarks of a track buckle also,” Quimby said. “Sometimes a locomotive, which is heavier, will make it through” a buckled track, “but the cars following won&r
And what did Russ say when asked why this didn’t happen several weeks earlier, when the temperature was 12 degrees higher?
And how did Russ know it was heat caused instead of a failure in track/roadbed installation?
Ed
As I have mentioned, sun kinks do not just occur when ambient temperature reaches a certain point. You can’t rule out a sun kink just because temperatures have been higher and no sun kink occurred.
What Mr. Quimby and I are saying is that a sun kink may or may not have been the cause, but that circumstantial evidence points to a sun kink as the cause. Mr. Quimby cites evidence for a sun kink derailment in that the locomotives in front did not derail, but eight lighter coach cars behind them did.
As I have mentioned, sun kinks not yet apparent have a tendency to be triggered into actual track misalignment as the train proceeds over the heat overstressed track zone. This is often results in the locomotive not derailing because it never encounters misaligned track.
Instead, it creates misaligned track trailing out behind the locomotive. Also, if track is misaligned before the locomotive reaches it, it may make it across safely because it is heavier than the trailing cars and thus it can hold the track better. In either case, the misalignment is likely to grow larger as the train passes through the danger zone.
However you seem to be positively asserting that a sun kink was not the cause. How
In the picture from overhead, the rails nearest the three rear cars are bowed apart. Does that add to the sun link theory (stress relief)? North rail bowed North and South bowed South.
I’m guessing nobody asked Russ those questions.
I’m not positively asserting any cause for this wreck. I’m expressing doubts and asking questions about your sun kink concept.
Ed
I agree that you are not asserting a cause for the wreck. But what I said was that you are positively asserting that a sun kink was not the cause. And you are indeed doing that. Your statements indicate that. You have ruled out sun kink as the cause because there were no sun kinks when the temperature was higher than at the time of the Montana wreck. So you conclude that the temperature was not high engough to cause a sun kink in relation to the Montana wreck.
And you can show that by quoting me, of course. Please do.
No. I have asked why it didn’t happen at the higher temperature. Why do you think asking a question would rule something out.
Nope. But I do have doubts.
You seem to confuse having doubt and asking questions with negative certainty.
To be CLEAR:
I DO NOT ASSERT THAT THE CAUSE OF THIS WRECK WAS NOT A SUN KINK.
I believe the most likely cause was defective maintenance for the track/roadbed. The sun/heat MAY have exacerbated it, but I think it did not CAUSE the problem. Put another way, if the maintenance was done properly, I think there would not have been a derailment.
Note the words “I believe…” and “…most likely…”. Clearly, that leaves room for others to believe differently. As you do.
Ed
Not criticizing you for passing this along, but I don’t know if I buy this theory. Common sense would tell me that a heavy locomotive, in a curve, would apply more outward force than a lighter piece of rolling stock would, therefore making it more likely that the engine(s) would force the outer rail outward and splay the track.
LINKED MEDIA QUOTE FROM PRIOR POST:
“Russ Quimby, a former rail-accident investigator for the NTSB, said heat is the most likely explanation. He is convinced because the locomotives in front did not derail, but eight lighter coach cars behind them did.
“This has all the earmarks of a track buckle also,” Quimby said. “Sometimes a locomotive, which is heavier, will make it through” a buckled track, “but the cars following won’t. You saw that in this accident,” he said.”
I agree with your point. Mr. Quimby makes the point to explain why locomotives tend to not derail in sun
Are you sure about this? As heat causes the rail to expand in length, it seems to me it quickly reaches a point where that causes it to kink.
It would seem that way if the thermal expansion was an irresistible force, but it is not. If the rail is sufficiently constrained, its linear expansion can be restrained during thermal expansion.
The rail steel is made with sufficient elasticity, to make a rail act like a coil spring when squeezed end to end, and then rebound when the squeeze is released. It can also be stretched end to end and elongate like a coil spring, and then rebound from the stretch when the force is removed.
So if you heat rail that is constrained end to end, the steel itself will compress like bread dough. So the heated and constrained rail will absorb the expansion within the steel itself.
If rail could not be restrained from liner expansion by its elasticity, then it would indeed almost immediately cause buckling when heated. But such buckling would be v