https://www.ntsb.gov/investigations/AccidentReports/Reports/RIR2405.pdf
After receiving the report from the third detector, the3 engineer began slowing the train, intending to stop, using only dynamic breaking. Why not blended braking for a faster, non-emergency, service stop? Probably because he decided tread braking would heat the wheel even more.
Thanks, Overmod, and comment, please?
Using air brakes on freight cars provides a single point of force against the wheel tread - what makes the brake effective is that the force is acting against the axle of the wheel. If the axle is, in fact, overheated - the brake application can be the force that causes the axle to snap. As a engineer, he doesnât know the exact condition of the suspected axle, and thus doesnât want to provide additional force against the axle by using the air brakes.
I have not yet read the report, but I will be looking for a detailed explanation of each step of the process leading right up to the buckling and piling up of railcars. This wrecking process is typically referred to as a âderailment,â but derailment is just the first wheel to go on the ground. It has a cause.
But there is also a process in which the train buckles from rising buff force, and begins a process of jackknifing railcars in a destructive cascade. I call that a pileup. It also has a cause.
There can be a long distance between the initiation of the derailment and the onset of the pileup. The two events can be miles apart, and each having their own cause. If a train is stopped in time, there may never be a pileup even though the derailment occurred and has run the train on the ground for a long distance.
It seems to me that the report is conveying this impression:
The detector issued a hot bearing warning to stop.
The axle burned off and this initiated the derailment.
The Undesired Emergency (U.D.E.) application of the air brakes occurred as an indication that the train had begun to buckle and pile up.
However, in the report, we are told that the derailment began at least 1,400 feet before any of the above occurred; and during that time, the derailed cars involved were all running in line with the rails, apparently being guided by the rails, but not being borne by them. So 1,400 feet of cars were running derailed, but not developing any pileup.
Since the burning off of the axle is said to have caused the whole derailment and pileup, where was the axle in this progression when it burned off?
If the axle burned off when it was within t
The Euclid Mind Derailer.
Sure, blame it on EMDâŚ
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[bow]
/https://www.ntsb.gov/investigations/AccidentReports/Reports/RIR2405.pdf
Page 49 - Figures 18 & 19 tell you all you need to know about the cause.
Everything else is conjecture about how it got to that state and what happened after.
The NTSB is not presenting anything as conjecture, so why do you think it is conjecture?
I have been looking at Page 49, fig. 18 & 19, and other information in that general area. In the preliminary details that were being collected, there were all of those photos that are shown here, plus other photos that have been omitted from this final report.
For instance, in that earlier display of photos, there was a photo of the axle with one journal burned off and appearing as burned off axles normally do, almost as if having been cut off with a lathe. Unless I am missing something, the NTSB now says that the failing bearing, eventually burned the axle off and that began the derailment. So where is the burned off axle that was shown in those earlier photos a few months ago?
Because everything about an incident such as this is most often a âmost likelyâ case. No one saw the axle actually fail - all we have is some heat readings and doorbell cams.
Certain things can come awfully close - they may well have found the spot where the failed truck most likely âdug in,â causing the pile-up. But there are no witnesses that can provide specifics. No one to say that the axle actually failed right behind Johnsonâs Hardware Store (fictitious - for sake of discussion).
Itâs a shame you werenât part of the investigation team. Expertise such as yours is hard to findâŚ
Critical element in whether there is a pile up of one variety or another - what was the speed of the train when the offending car âhit the groundâ. The irregular nature of the the under car profile makes it more likely than not that âsomethingâ will âsnagâ something in the track structure and that snag will create forces unsettling the car in one more planes and that car becomes the âstopping powerâ upon which the trailing tonnage at whatever speed is acting against - I feel certain an engineer with lots of time and computer power could create a model of the stresses of each car each second until all the tonnage dissapates its kinetic energy and the entire train comes to a stop.
If the speed is low and the trailing tonnage is negligible then the likelyhood of a major pile up is low. If the speeds and tonnages are high, the general pile up is highly likely. If the grade is descending the pile up will tend to be worse than if the grade is ascending or level - the basic physics of mass are at play.
Euc, you need to get away from the keyboard and spend some time on the ground investigating the various aspects of derailments.
The NTSB says the hot bearing melted off the axle that was next to the bearing, and the loss of that axle support caused the derailment. It surely can and does work that way sometimes. In such a case, the part of the axle is often found on the ground near the beginning of the heap of cars if there is a pileup. Where, and in what sort of damaged condition was the axle found in the case of this wreck? There is a lot of evidence left in a wreck like this, and it will disclose many facts. Apparently, in this case, the burned off axle did not initiate the pileup. Perhaps other parts of the truck frame assembly broke up and started the pileup. Axles can also burn off and not cause a pileup. Also, a train can burn off an axle and pile up for another reason than the burned off axle.
As to the speed of the train, I recall reading that the speed limit for the train when entering the town was 50 mph, and their actual speed of the train was 43 mph. I have not absorbed all of the accident report yet, but I have found wha
Had the engineer applied the air brakes, the axle would have rung off once the brake shoe applied pressure to the wheel tread. Tread air brakes require that the axle be âsolidâ in order to allow the pressure of the brake shoe to apply the braking force to the tread. Once the brake shoe applies force to the wheel tread, it will then displace the wheel if the axle is no longer strong enough to hold the wheel in its designed position.
If you get a Hot Box indiciation from a Defect Detector or from a employee or someone along the right of way - YOU DO NOT USE AIR BRAKES to bring the train to a stop, except as a last resort.
If a train has a hot bearing on a railcar, and is in the process of burning off the axle, an air brake application will accelerate the rate of burn-off, as you say.
If a train has a hot bearing that has already burned off an axle, and thus the railcar is dragging derailed; any amount of buff force in the train will tend to buckle the train laterally at the joint of the burned off axle.
Such buff force can be produced by an air brake application; and will be highly likely to be produced by a dynamic brake application made ahead of the derailed dragging car. The only factor that could prevent buckling in that circumstance of dynamic braking is lateral resistance in the trackwork that is capable of maintaining the derailed car tracking ability.
The railcar with the failing bearing at East Palestine was derailed and dragging for at least 1,400 feet and then something caused the train to buckle at or near the joint with the hot bearing. That buckling began the process of jackknifing and pileup. I
Euc - are you trying to contend that if the engineer had power braked, hard enough to keep the slack stretched throughout the train that there would not have been a multi-car derailment?
I would not draw that conclusion because of all the variables. But yes; I do think that method of braking could have prevented the pileup; but not the way it was configured in this incident.
In any case, there would not be any âpower braking.â Power would not be applied as though the objective was keep the train stretched such as when going down a grade.
What would act to keep the train stretched in this case would be only the dynamic braking.
And also, it would be only dynamic braking of DPU engines; only those behind the car with the hot bearing. They would be decelerating the train in a way that would keep it stretched through the location of the hot bearing. There would also be no dynamic braking ahead of the hot bearing car because that would have the opposite effect of having the train bunched behind the head end, and for some distance toward the hind end. The car with the hot bearing was very close to the head end (I recall about 20 car lengths), so probably would have been in bunched slack if dynamic braking were applied by the head end po
nah⌠nevermind.
[quote user=âEuclidâ]
BaltACD
Euc - are you trying to contend that if the engineer had power braked, hard enough to keep the slack stretched throughout the train that there would not have been a multi-car derailment?
I would not draw that conclusion because of all the variables. But yes; I do think that method of braking could have prevented the pileup; but not the way it was configured in this incident.
In any case, there would not be any âpower braking.â Power would not be applied as though the objective was keep the train stretched such as when going down a grade.
What would act to keep the train stretched in this case would be only the dynamic braking.
And also, it would be only dynamic braking of DPU engines; only those behind the car with the hot bearing. They would be decelerating the train in a way that would keep it stretched through the location of the hot bearing. There would also be no dynamic braking ahead of the hot bearing car because that would have the opposite effect of having the train bunched behind the head end, and for some distance toward the hind end. The car with the hot bearing was very close to the head end (I recall about 20
Euclid, go back to either the STB Public Hearing Docket or the Final Report Docket, download the Event Recorder file and then you can see what actions were taken by the engineer and the corresponding reactions of the DPU (which was located after the 109th car) both before and after the point of derailment. There are three time frames to examine- the third set has the shortest timeframe and most relevant details